Academic literature on the topic 'Seedling Infection'
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Journal articles on the topic "Seedling Infection"
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Blenis, Peter V., Kathleen L. Wiggins, James E. Cunningham, and Michael A. Pickard. "Maltol protects against infection of lodgepole pine seedlings by western gall rust." Canadian Journal of Forest Research 18, no. 12 (1988): 1658–60. http://dx.doi.org/10.1139/x88-252.
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Uptake and translocation of maltol into 6-week-old Pinusconforta (Engelm.) var. latifolia seedlings was followed by means of gas chromatography. Maltol concentrations of 6.0–7.3 mg/g seedling dry weight (46–55 μg/seedling) were observed over the first 3 days following a single application of 50 mg maltol/seedling. A split-plot design was used to determine if maltol could reduce seedling infection by Endocronartiumharknessii. Whole plots consisted of two inoculum levels (7 or 30 mg of spores per tray of seedlings) and subplots consisted of four levels of maltol (0, 2, 10, or 40 mg/mL) applied 2 days before inoculation to one-half tray of seedlings at the rate of 5 mL/cavity. The highest concentration consistently and significantly reduced seedling infection relative to the untreated control, although it also caused some phytotoxicity.
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Bachand, George D., John D. Castello, Michail Schaedle, Stephen V. Stehman, and William H. Livingston. "Effects of tomato mosaic Tobamovirus infection on red spruce seedlings." Canadian Journal of Forest Research 26, no. 6 (1996): 973–81. http://dx.doi.org/10.1139/x26-107.
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Height, weight, root volume, shoot length, needle length and weight, and total chlorophyll content were measured for both control and tomato mosaic Tobamovirus (ToMV)-inoculated red spruce (Picearubens Sarg.) seedlings in each of five, 3-month growth periods. Mean bud-break rating was determined for each seedling in growth period 5. In January 1995 the freezing tolerance of control and ToMV-infected seedlings was determined. Approximately 85% of the inoculated seedlings became infected with ToMV, as determined by enzyme-linked immunosorbent assay of young root tissue. Reduction in seedling height, weight, root volume, bud break, and mean shoot length of infected seedlings was observed when compared with control seedlings. The rate of increase over time in height, weight, and root volume was lower (54, 57, and 52%, respectively) in infected seedlings compared with control seedlings. Additionally, needles of infected seedlings were less susceptible to freezing damage than those of control seedlings. However, virus infection had no effect on the freezing tolerance of roots.
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Kolmer, J. A. "Virulence in Puccinia recondita f. sp. tritici Isolates from Canada to Genes for Adult-Plant Resistance to Wheat Leaf Rust." Plant Disease 81, no. 3 (1997): 267–71. http://dx.doi.org/10.1094/pdis.1997.81.3.267.
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Sixty-seven isolates of Puccinia recondita f. sp. tritici collected in Canada were tested for virulence to adult plants of Thatcher near-isogenic wheat lines with leaf rust resistance genes Lr13, Lr22a, Lr34, Lr35, and Lr13 and Lr34 combined. All of the isolates had low infection type to the Thatcher lines with Lr22a and Lr35. All isolates had lower infection type and lower rust severity on the Thatcher line with Lr34 compared with Thatcher. The isolates were polymorphic for virulence to the Thatcher line with Lr13; many isolates were completely virulent to this line, and other isolates produced very low or intermediate avirulent infection type. On the Thatcher line with Lr13 and Lr34 combined, many isolates had infection type and rust severity similar to the Thatcher line with Lr34, while other isolates had lower infection type and rust severity compared with the single-gene lines with Lr13 or Lr34. Fifteen isolates with low, intermediate, and high infection type to adult plants with Lr13 were tested for infection type on seedling plants of the Thatcher lines with resistance genes Lr13, Lr22a, Lr34, Lr35, and Lr37, and on Thatcher lines with Lr13 paired with seedling resistance genes. Most isolates were completely virulent to seedling plants with Lr13 and Lr22a. Plants with Lr37 expressed seedling resistance to all isolates tested. Seedling plants with Lr34 had lower infection types to all isolates compared with Thatcher. Seedlings with Lr35 had high infection types to most isolates, with varying amounts of chlorosis. The Thatcher lines with Lr13 plus seedling resistance genes were most resistant to the isolates that had very low infection types on adult plants with Lr13 and intermediate infection types on plants with seedling resistance genes. Genes Lr22a, Lr35, and Lr37 offer additional sources of highly effective leaf rust resistance in wheat.
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Williams-Woodward, J. L., F. L. Pfleger, R. R. Allmaras, and V. A. Fritz. "Aphanomyces euteiches Inoculum Potential: A Rolled-Towel Bioassay Suitable for Fine-Textured Soils." Plant Disease 82, no. 4 (1998): 386–90. http://dx.doi.org/10.1094/pdis.1998.82.4.386.
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A sensitive measure of soil inoculum potential is needed to evaluate field management of common root rot (Aphanomyces euteiches) in peas (Pisum sativum). A modified rolled-towel (RT) bioassay had been proposed to measure soil inoculum potential in fine-textured soils used for pea production in Minnesota. Homogenized soil was used because organic debris containing the inoculum could not be separated by wet sieving. The poor precision prompted an evaluation of procedures to improve this modified RT bioassay. Seed treatment with a 5% solution of sodium hypochlorite before pea seed germination and plant isolation procedures during the RT bioassay preparation/incubation reduced seedborne contamination and seedling loss to less than 5%. Tests conducted with pasteurized soil that was artificially infested with oospores showed the region of the pea taproot 1 to 2 cm below the seed to be more susceptible to infection (33% compared with 15% infected seedlings) than the region 1 to 2 cm above the root tip. A soil volume of 1.0 cm3 increased inoculum potential compared with 0.5 cm3 applied to each seedling but did not influence the random error; the 40-seedling compared with the 20-seedling RT bioassay reduced random error from 18 to 12%. The modified RT bioassay conducted on soil that was artificially infested after steam treatment or without steam treatment showed superior performance when using 40 seedlings compared with 20 seedlings when evaluated for accuracy and precision. Multiple infection theory demonstrated more multiple infections in the RT bioassay with a 0.5 cm3 soil volume applied to each seedling, which shows that soil mass is a factor preventing a higher percentage of infected seedlings. These modifications to the RT bioassay improved the method enough to reduce the random error by one-half compared with using homogenized soil without the proposed modifications.
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Yates, I. E., C. W. Bacon, and D. M. Hinton. "Effects of Endophytic Infection by Fusarium moniliforme on Corn Growth and Cellular Morphology." Plant Disease 81, no. 7 (1997): 723–28. http://dx.doi.org/10.1094/pdis.1997.81.7.723.
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Kernels of corn, Zea mays, were inoculated with Fusarium moniliforme to analyze seedling growth and development during endophytic, symptomless infection. In planta F. moniliforme distribution and seedling growth, expressed as shoot diameter, plant height, leaf length, and dry weight, were examined weekly for 28 days after planting. Even though no visible disease symptoms developed, F. moniliforme was isolated from most segments taken from seedlings grown from inoculated, but not noninoculated, kernels from the earliest to the latest sampling. F. moniliforme did not alter the rate or percentage of kernel germination, but seedlings grown from inoculated kernels had suppressed shoot diameter, plant height, leaf length, and plant weight 7 days after planting. However, seedling growth from inoculated kernels was similar to or greater than that from noninoculated kernels at 28 days. Histological modifications in seedlings grown from inoculated kernels included accelerated lignin deposition in shoots and modified chloroplast orientation in leaves. In summary, gross morphology and histology were altered in corn seedlings during symptomless, endophytic infection by F. moniliforme.
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Chung, Kuang-Ren, Walter Hollin, Malcolm R. Siegel, and Christopher L. Schardl. "Genetics of Host Specificity in Epichloë typhina." Phytopathology® 87, no. 6 (1997): 599–605. http://dx.doi.org/10.1094/phyto.1997.87.6.599.
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Epichloë typhina perennially and systemically infects grass plants, causing choke disease in which maturation of host inflorescences is suppressed. In seedling-inoculation tests, isolate E8 from perennial ryegrass established and maintained infection in this host but not in orchardgrass. In contrast, isolates E469, E2466, and E2467 from orchardgrass varied in infection frequency and stability in orchardgrass, but all were unable to establish stable infections in perennial ryegrass. To investigate the genetics of host specificity, isolate E8 was crossed with each of the isolates from orchardgrass. Seedlings of parental host species were inoculated with F1 progeny, and the frequencies of seedling infection and stability in adult plants were assessed. In the E8 × E2466 cross, the F1 progeny exhibited a wide range of infection frequency and stability in each parental host. In crosses E8 × E469 and E8 × E2467, where the orchardgrass-derived parents infected 5 to 13% of inoculated perennial ryegrass seedlings, the distributions of infection frequencies for the F1 progeny wereskewed toward levels comparable to that of the parent from perennial ryegrass. In all crosses, most progeny had low frequencies of infection in orchardgrass. However, transgression was evident in a cross of E8 with E469, an isolate that infected orchardgrass seedlings at a low frequency (2 to 3%). The E8 × E469 cross had a few F1 progeny that infected orchardgrass at high efficiency (up to 81%). A Spearman rank correlation applied to the E8 × E2466 progeny indicated a significant negative correlation between infection frequencies in perennial ryegrass and orchardgrass. Also, there was a significant correlation of infection frequency and stability in perennial ryegrass but not in orchardgrass. To test whether only a few genes governed infection frequency in perennial ryegrass, an E8 × E2466 F1 progeny (designated E386.04), which had intermediate compatibility with this host, was backcrossed to E8. The progeny of this backcross exhibited a distribution of infection frequencies in perennial ryegrass between that of E386.04 and the backcross parent, suggesting that multiple genes may determine compatibility at the seedling infection stage. The results of these experiments indicated multiple genetic determinants of compatibility or incompatibility with each host, with intermediate or high heritability.
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Barrit, Thibault, Elisabeth Planchet, Jérémy Lothier, et al. "Nitrogen Nutrition Modulates the Response to Alternaria brassicicola Infection via Metabolic Modifications in Arabidopsis Seedlings." Plants 13, no. 4 (2024): 534. http://dx.doi.org/10.3390/plants13040534.
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Little is known about the effect of nitrogen nutrition on seedling susceptibility to seed-borne pathogens. We have previously shown that seedlings grown under high nitrate (5 mM) conditions are less susceptible than those grown under low nitrate (0.1 mM) and ammonium (5 mM) in the Arabidopsis-Alternaria brassicicola pathosystem. However, it is not known how seedling metabolism is modulated by nitrogen nutrition, nor what is its response to pathogen infection. Here, we addressed this question using the same pathosystem and nutritive conditions, examining germination kinetics, seedling development, but also shoot ion contents, metabolome, and selected gene expression. Nitrogen nutrition clearly altered the seedling metabolome. A similar metabolomic profile was observed in inoculated seedlings grown at high nitrate levels and in not inoculated-seedlings. High nitrate levels also led to specific gene expression patterns (e.g., polyamine metabolism), while other genes responded to inoculation regardless of nitrogen supply conditions. Furthermore, the metabolites best correlated with high disease symptoms were coumarate, tyrosine, hemicellulose sugars, and polyamines, and those associated with low symptoms were organic acids (tricarboxylic acid pathway, glycerate, shikimate), sugars derivatives and β-alanine. Overall, our results suggest that the beneficial effect of high nitrate nutrition on seedling susceptibility is likely due to nutritive and signaling mechanisms affecting developmental plant processes detrimental to the pathogen. In particular, it may be due to a constitutively high tryptophan metabolism, as well as down regulation of oxidative stress caused by polyamine catabolism.
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Milus, Eugene A., Kevin D. Lee, and Gina Brown-Guedira. "Characterization of Stripe Rust Resistance in Wheat Lines with Resistance Gene Yr17 and Implications for Evaluating Resistance and Virulence." Phytopathology® 105, no. 8 (2015): 1123–30. http://dx.doi.org/10.1094/phyto-11-14-0304-r.
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Stripe rust, caused by Puccinia striiformis f. sp. tritici, has been the most important foliar wheat disease in south central United States since 2000 when a new strain of the pathogen emerged. The resistance gene Yr17 was used by many breeding programs to develop resistant cultivars. Although Yr17 was classified as a seedling (all-stage) resistance gene conferring a low infection type, seedlings with Yr17 frequently had intermediate to high infection types when inoculated with isolates that caused little or no disease on adult plants of the same wheat lines. The objectives of this study were to determine how to best evaluate Yr17 resistance in wheat lines and to determine which factors made seedling tests involving Yr17 so variable. Stripe rust reactions on wheat seedlings with Yr17 were influenced by temperature, wheat genotype, pathogen isolate, and the leaf (first or second) used to assess the seedling reaction. The most critical factors for accurately evaluating Yr17 reactions at the seedling stage were to avoid night temperatures below 12°C, to use the first leaf to assess the seedling reaction, to use multiple differentials with Yr17 and known avirulent, partially virulent and virulent isolates as controls, and to recognize that intermediate infection types likely represent a level of partial virulence in the pathogen that is insufficient to cause disease on adult plants in the field.
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Ahn, Ezekiel, Louis K. Prom, Coumba Fall, and Clint Magill. "Response of Senegalese Sorghum Seedlings to Pathotype 5 of Sporisorium reilianum." Crops 2, no. 2 (2022): 142–53. http://dx.doi.org/10.3390/crops2020011.
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Sporisorium reilianum causes head smut in sorghum. A total of 36 Senegalese sorghum accessions comprised of sorghum lines that have not been explored with response to pathotype 5 of S. reilianum were evaluated with 3 different treatments. First, seedling shoots were inoculated while still in soil with teliospores in agar, and then submerged under water at 4 days post inoculation. Signs of infection (noticeable spots) on the first leaf were observed up to 6 days post submergence. Second, seedlings at the same stage were inoculated by placing the teliospore impregnated agar around the stem in pots, moved to a greenhouse and grown to full panicle development stage. Third, seedings were inoculated via syringe inoculation in the greenhouse. Although soil inoculated seedlings grown in the greenhouse did not result in systemic infection as determined by lack of symptoms at panicle exsertion, 88.9% of tested cultivars showed systemic infections when syringe inoculated in the greenhouse. Inoculation of seedlings maintained under water led to broad range of noticeable spots that are assumed to be potential infection sites based on a previous study. In addition, seedling inoculation led to slightly upregulated expression of chitinase and PR10, genes that are associated with defense in aerial parts of plants.
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Chun, S. C., and R. W. Schneider. "Sites of Infection by Pythium Species in Rice Seedlings and Effects of Plant Age and Water Depth on Disease Development." Phytopathology® 88, no. 12 (1998): 1255–61. http://dx.doi.org/10.1094/phyto.1998.88.12.1255.
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Seedling disease, caused primarily by several species of Pythium, is one of the major constraints to water-seeded rice production in Louisiana. The disease, also known as water-mold disease, seed rot, and seedling damping-off, causes stand reductions and growth abnormalities. In severe cases, fields must be replanted, which may result in delayed harvests and reduced yields. To develop more effective disease management tactics including biological control, this study was conducted primarily to determine sites of infection in seeds and seedlings; effect of plant age on susceptibility to P. arrhenomanes, P. myriotylum, and P. dissotocum; and minimum exposure times required for infection and seedling death. In addition, the effect of water depth on seedling disease was investigated. Infection rates of seed embryos were significantly higher than those of endosperms for all three Pythium spp. The development of roots from dry-seeded seedlings was significantly reduced by P. arrhenomanes and P. myriotylum at 5 days after planting compared with that of roots from noninoculated controls. Susceptibility of rice to all three species was sharply reduced within 2 to 6 days after planting, and seedlings were completely resistant at 8 days after planting. There was a steep reduction in emergence through the flood water, relative to the noninoculated control, following 2 to 3 days of exposure to inoculum of P. arrhenomanes and P. myriotylum. In contrast, P. dissotocum was much less virulent and required longer exposure times to cause irreversible seedling damage. Disease incidence was higher when seeds were planted into deeper water, implying that seedlings become resistant after they emerge through the flood water. These results suggest that disease control tactics including flood water management need to be employed for a very short period of time after planting. Also, given that the embryo is the primary site of infection and it is susceptible for only a few days, the disease should be amenable to biological control.
Dissertations / Theses on the topic "Seedling Infection"
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Newton, A. C. "Mineral nutrition and mycorrhizal infection of seedling oak and birch." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306551.
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Malligan, Cassandra D. "Crown rot (fusarium pseudograminearum) symptom development and pathogen spread in wheat genotypes with varying disease resistance." University of Southern Queensland, Faculty of Sciences, 2009. http://eprints.usq.edu.au/archive/00006225/.
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[Abstract]Crown rot, caused by Fusarium pseudograminearum (Fpg), is an important soilborne disease of wheat and barley. The degree of crop damage depends on seasonal conditions. Typically, high moisture conditions early in the season encourage seedling infection from stubble residues. Moisture stress later in the season leads to the production of unfilled “whiteheads”. Current control relies on cultural practices and sowing of partially resistant varieties. In order to understand the nature of partial resistance, I have examined the patterns of disease symptom development and pathogen spread in susceptible and partially resistant tissues of both pot-grown wheat, barley and oat seedlings and field-grown inoculated wheat trials. Further research was conducted to determine whether differences in pathogenicity occur amongst a small subset of Australian Fpg isolates. Seedling experiments confirmed that differences in disease ratings between susceptible and partially resistant genotypes are detected in younger leaf sheaths of older seedlings. At later harvest times differences between these genotypes are not significant in older leaf sheaths. Re-isolation of Fpg from inoculated seedlings has shown that each tissue was infected later in partially resistant genotypes compared to susceptible ones with a significantly lower number of isolations recorded at each harvest time in 42 day old seedlings. Barley cultivars were rapidly infected by the pathogen and exhibited high levels of disease symptoms. By comparison levels of infection in oats were low compared to all other genotypes. No significant differences between genotypes were observed in coleoptile tissues, either in fungal colonisation or development of disease symptoms. Disease development in the subcrown internode varied between lines/cultivars but was not representative of the relative susceptibility of each genotype. The pathogen did not appear to invade plant tissue via the vascular system but rather spread directly across the stem from leaf sheath to leaf sheath. Field trials were designed to study disease symptom development and localisation of Fpg hyphae in all expanded tissues (excluding head and roots) in wheat genotypes of known susceptibility to crown rot. Plants were harvested at approximately fortnightly intervals throughout the growing season. The main effects and interactions of harvest, genotype and tiller on each plant part were examined with a detailed statistical analysis of differences seen in these factors between susceptible and partially resistant wheat genotypes, in two inoculated field trials. While differences between genotypes were mostly not significant at each harvest when disease rating or isolations from leaf sheath tissues were examined, important differences between susceptible and resistant genotypes were seen in disease developments and Fpg infections of stem tissue in field trials. Restriction of pathogen growth and symptom development was more pronounced in the tissues of 2-49 (possesses seedling resistance) than in the field resistant Sunco. At present, the mechanisms that lead to these resistance responses are unknown. The pathogenicity study aimed to determine whether 7 Fpg isolates and a mixed inoculum differed in ability to cause crown rot in 9 wheat genotypes ranging in susceptibility to this disease. Although a genotype*inoculum interaction was significant, there is no evidence of stable pathogenic races in the isolates examined in these experiments. The growth of all isolates was partially inhibited in a consistent manner on resistant genotypes when compared to very susceptible genotypes. These results confirm significant differences in the aggressiveness of Fpg isolates on wheat, evidenced by variation in mean disease severity between isolates growing on a range of host genotypes.
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Fautley, Robin Hayes. "Seedling growth and survival of Abies magnifica and A. concolor as affected by mycorrhizal infection /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Coltman, Paul Michael. "The response of apple seedlings to inoculations with conidial suspensions of Venturia inaequalis Cke. Wint." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/847325/.
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Percentage in-vitro conidial germination of inaequalis was inversely related to the log conidial concentration. The filtrate from a conidial suspension of inaequalis was shown to inhibit conidial germination. Ferrous iron was shown to reduce conidial germination. Anthranillic acid reversed the inhibitory action of ferrous iron and enhanced germination of conidial suspensions not containing additional iron. Continuous rolling or ''pre-treatment" of conidial suspensions of V. inaequalis used for inoculum increased levels of infection. It was suggested that this improvement may be a result of higher numbers of germinated conidia present on the leaf surface. Pre-treatment of inocula was adopted as a standard inoculation technique. Symptom expression was studied under two categories :- i) Effect on seedling growth (stunting/promotion) ii) Foliar symptoms (total disease expression score - TDE) Stunting and TDE values were correlated to lesion number and positively correlated to inoculum concentration. High inoculum concentrations caused stunting and low ones resulted in growth promotion. Similar responses were found with all apple varieties tested. Experimental evidence was presented to support the hypotheses :- 1) Conidia only produce stunting. 2) The filtrate from a pre-treated conidial suspension of V. inaequalis contained a factor which induced growth promotion of apple seedlings. Washing pre-treated conidia with GDW immediately before inoculation enhanced stunting of apple seedlings. Foliar sprays of the pre-treatment filtrate promoted seedling growth, concentrating it further enhanced promotion. The factor responsible was resistant to boiling, suggesting it to be non-protein but after standing for 24 h lost its ability to promote growth. Bioassays of the filtrate for IAA and cytokinins were negative. A dock leaf disk test was positive for gibberellins. Analysis of the filtrate using mass spectrometry indicated the presence of high molecular weight ions but it was not possible to identify any particular fragment or conclude whether these could be responsible for growth enhancement. It is suggested that the filtrate acts by increasing cell elongation rather than cellular proliferation. Use of the fungicides dodine and captan produced a host response to infections by inaequalis ranging from stunting to growth promotion. The potential of pre-treatment and symptom assessment for use as a fungicide screening technique was demonstrated. It was suggested that summation of the ranked scores for TDE and phytotoxic stunting provided an accurate assessment of a chemical's suitability for further testing.
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See, Lee Su. "Some aspects of the biology of mycorrhizas of the Dipterocarpaceae." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334651.
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Little is known of the biology and importance of the ectomycorrhizal symbiosis in the Dipterocarpaceae. This project was undertaken: 1) to follow dynamics of mycorrhizal infection of dipterocarp seedlings at different sites in the forest, to characterise the major fungal associations involved; 2) to follow mycorrhizal infection of dipterocarp seedlings under laboratory conditions with different inoculum sources; 3) to determine whether dipterocarp ectomycorrhizas function in a manner similar to temperature ectomycorrhizas in the uptake of specific nutrients. Twenty-four different ectomycorrhizal types were described from roots of newly germinated seedlings, two to seven month-old seedlings and wildings of <i>Shorea leprosula</i> (Miq.), and approximately 20 year-old <i>S. acuminata</i> Dyer, <i>S. dasyphylla</i> Foxw., <i>S. leprosula</i> and <i>S. parvifolia</i> Dyer trees. Seventeen types were tentatively identified to family level. Vesicular-arbuscular mycorrhizas were not found. In the forest, some 14 day-old <i>S. leprosula</i> seedlings were already ectomycorrhizal but infection could be absent up to seven months after germination. The results implied that hyphal connections were important in early infection of seedlings in the vicinity of parent trees. Mycorrhizal infection of sequentially sampled two to seven month-old seedlings declined over the sampling period at two sites in Gombak, Selangor and one in Ulu Langat, Selangor. Five to six ectomycorrhizal types were dominant on seedlings at each site and a succession of types was observed on seedling roots. At final harvest, increased plant growth was significantly correlated with ectomycorrhizal infection only at one site in Gombak where infection by 'dominant' types exceeded 30%. Non-mycorrhizal seedlings of <i>S. acuminata, S. leprosula, Hopea helferi</i> and <i>H. odorata</i> were able to grow normally in sterile soil under non-competitive situations. Seedlings were able to form ectomycorrhizas even with inoculum present in grassland soils or with inoculum from different host species in the case of <i>H. helferi</i>. Increased phosphorus uptake by ectomycorrhizal seedlings of <i>S. acuminata, S. leprosula</i> and <i>H. odorata</i> was demonstrated.
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Pei, Ming Hao. "Peridermium pini (Pers.) Lév.-Axenic culture and infection of pine callus tissue cultures and young seedlings." Thesis, University of Aberdeen, 1989. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU553195.
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Axenic cultures of Peridermium pini have been established on modified Shenk &'38 Hilderbrandt's and Harvey &'38 Grasham's media from naturally infected cortex tissues and aeciospore-infected calluses of P. sylvestris and from aeciospores collected from NE Scotland and East Anglia. The cultures occasionally produced immature smooth-surfaced, binucleate spores. Actively growing cultures infected P. sylvestris calluses but not seedlings or trees. In the experiment of fungal nutrition, (NH4)2SO4 appeared essential, sucrose, D-glucose, raffinose and D-sorbitol supported good growth while D-xylose, cellobinose and L-arabinose did not. Opt. medium pH proved to be 5.0-6.0. Axenic cultures were also obtained from 30-40&'37 of single sporelings of some East Anglia spore sources but not from NE Scotland sporelings. When inoculated at a high density, however, all spore sources from both East Anglia and NE Scotland readily formed colonies. Colonies from East Anglia spores mostly appeared smooth at the surface and distinct around margin while those from NE Scotland sources had fluffy surface and irregularly extended periphery. Rapidly expanding hyphal layers developed from both of the colony forms 3 months after inoculation. Callus tissue cultures of P. sylvestris, P. nigra var. maritima and P. mugo vars mughus, rostrata and pumilio were infected by inoculation with aeciospores from NE Scotland. Infections were characterized by formation of aerial hyphae on the callus surface and intercellular hyphae and typical haustoria in the callus tissue. Hyphae from some of the infected calluses penetrated the medium. Seedlings of the pines as above were infected at their cotyledon stage by inoculation with NE Scotland spores. Infections resulted in swelling, death of the seedlings and formation of spermogonia after a year and aecia after two years. Infections of young seedlings of 7 seed sources of P. sylvestris and the UK were examined 6 weeks after inoculation. Discolouration and necrosis of cotyledons were not always related to stem infection.
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Hoak, Jessica. "Tracking Tobacco Mosaic Virus Infection from Infected Seeds to Seedlings Confirms Seed Transmission in Tobacco (Nicotiana tabacum L.)." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/101702.
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The Tobacco mosaic virus (TMV) is a positive sense single stranded RNA virus and is found across the world. TMV can impact the overall yield and quality of the crop resulting in an economic loss. Plants that are infected with TMV show a variety of symptoms such as mosaic pattern, mottling, necrotic lesions and stunted growth. Historically, TMV has caused controversy on whether this economically significant virus is seedborne or seed transmitted. The objective of this study is to track TMV infection from infected seeds to seedlings to determine the percentage of seed transmission. This experiment used three pods from three different TMV infected cultivar K 326 flue-cured tobacco plants. Seeds from each pod were germinated in a growth chamber for approximately ten days. Samples were separated into seed coat, root and leaves after germination. Total RNA was extracted from each part and synthesized into cDNA for analysis. A quantitative real-time PCR (RT-qPCR) assay was used to determine TMV concentration of each sample. Endpoint RT-PCR was used to determine a conservative threshold value from the RT-qPCR results. These results demonstrated that TMV influenced percent germination with a range from 94% to 50%. Seed coats had a significantly higher virus titer concentration (P < 0.05) when compared to the roots and leaves. Statistical analysis revealed highly significant (P < 0.0001) differences among pods for virus titer and there is a highly significant plant by pod interaction (P < 0.0001). Endpoint RT-PCR confirmed TMV infection in leaves, roots and seed coats. Percent infection in leaves ranged from 2% to 24% and percent infection for roots ranged from 8% to 40%. Results demonstrate that TMV is seed transmitted in flue-cured tobacco.<br>Master of Science
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Hui, Elizabeth L. W. "The influence of insect larvae and seedling roots on the foraging behaviour of infective juveniles of Steinernema spp., Nematoda, rhabditida." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq37552.pdf.
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Orfanoudakis, Michail. "Symbiotic relationships of Alnus glutinosa with arbuscular mycorrhizal fungi and with Frankia." Thesis, University of South Wales, 2003. https://pure.southwales.ac.uk/en/studentthesis/symbiotic-relationships-of-alnus-glutinosa-with-arbuscular-mycorrhizal-fungi-and-with-frankia(c70364aa-677c-4611-a733-ffd98314a733).html.
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The occurrence in Scotland of arbuscular mycorrhizal fungi (AMF) infective on Alnus glutinosa and the effects on early growth of inoculation of seedlings with AMF and Frankia were investigated. AMF characteristic of G/omiw-like fungi were detected microscopically in A. glutinosa roots from mineral and loam but not from highly organic soils. Both GJomus- and Gigaspora-like fungi were detected only in roots from sandy soils. Glasshouse experiments showed that Glomus and Gigaspora species gave higher colonisation of roots, and were of higher compatibility with the host plant, than Acutelospora or Scutettospora species. Colonisation by AMF increased nodulation by Frankia and vice versa. Inoculation with AMF alone and dual inoculation with Gigaspora rosea and Frankia inhibited growth of young A. glutinosa seedlings. Initially after inoculation, AMF colonisation was poor allowing the host to meet the requirements of both developing symbioses. Mycorrhizal plants inoculated with Frankia 15 days after AMF inoculation, were under significant stress and this delayed the beneficial effects of AMF and Frankia symbiosis. Seedlings compensated for the cost of symbiosis by developing a larger, leafy shoot in a period of 25-30 days after AMF inoculation, with or with out, Frankia nodulation. A significant increase in root length and branching detected after inoculation with AMF and Frankia must impose additional energy requirements. However, the stimulation of lateral root branching that follows AMF colonisation may facilitate nutrient uptake, thus helping the plant to overcome the disadvantages of early retardation of shoot growth. Competition with adjacent plant species for below ground space may also be enhanced thus facilitating competition for growing space with other plant species. These factors may be part of a strategy that assists the survival of very young seedlings in the field. The data obtained suggest that delaying Frankia inoculation for 3-4 weeks after inoculation with selected AMF should improve the production in Scottish nurseries of robust, well nodulated and mycorrhizal seedlings.
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Zhang, Yulan. "Salmonella Infection on Arabidopsis Seedlings Requires Both Host and Pathogen Factors." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8934.
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Human enteric pathogen Salmonella contaminates raw produce and triggers significant economic loss and illness. Under a natural environment, Salmonella resides in soil and enters the interior of plants without causing disease or eliciting symbiotic growth. Upon being consumed by humans, complex virulence mechanisms are elicited by the specific intestine conditions, such as high temperature and humidity and lead to profound infection. The lack of effective prevention and drug treatment are largely attributed to the unclear mechanistic understanding on Salmonella association with environmental media, and in vivo host and pathogen factors required for persistent infection. We have explored the potential of deploying the model plant organism Arabidopsis thaliana to tackle this fundamental yet clinically challenging question, as Arabidopsis possesses many advantages as a model system, including enriched genomic resources, powerful genetic tools, low maintenance cost and a large collection of individual gene deletion mutants. Our preliminary data demonstrated Arabidopsis seedlings under liquid culture conditions mimicking the intestine environment were infected and killed by salmonella within 2 days upon inoculation. The Arabidopsis system possesses well-developed genetic information and the resources to study host factors required for infection on very short time scales, thus complementing traditional animal genetic studies. We aim to define the pathogen factors required for this infection. By merging the fields of extremely powerful Arabidopsis genetics and bacterial genetics/genomics, we hope to provide insight into possible new paradigms for addressing salmonella-mediated food born infection.
Books on the topic "Seedling Infection"
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James, Robert L. Fungal colonization of residual conifer seedling roots in soil: USDA Forest Service Lucky Peak Nursery, Boise, Idaho. U.S. Dept. of Agriculture, Forest Service, Northern Region, 1999.
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Gleń-Karolczyk, Katarzyna. Zabiegi ochronne kształtujące plonowanie zdrowotność oraz różnorodność mikroorganizmów związanych z czernieniem pierścieniowym korzeni chrzanu (Atmoracia rusticana Gaertn.). Publishing House of the University of Agriculture in Krakow, 2019. http://dx.doi.org/10.15576/978-83-66602-39-7.
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Horseradish roots, due to the content of many valuable nutrients and substances with healing and pro-health properties, are used more and more in medicine, food industry and cosmetics. In Poland, the cultivation of horseradish is considered minor crops. In addition, its limited size causes horseradish producers to encounter a number of unresolved agrotechnical problems. Infectious diseases developing on the leaves and roots during the long growing season reduce the size and quality of root crops. The small range of protection products intended for use in the cultivation of horseradish generates further serious environmental problems (immunization of pathogens, low effectiveness, deterioration of the quality of raw materials intended for industry, destruction of beneficial organisms and biodiversity). In order to meet the problems encountered by horseradish producers and taking into account the lack of data on: yielding, occurrence of infectious diseases and the possibility of combating them with methods alternative to chemical ones in the years 2012–2015, rigorous experiments have been carried out. The paper compares the impact of chemical protection and its reduced variants with biological protection on: total yield of horseradish roots and its structure. The intensification of infectious diseases on horseradish leaves and roots was analyzed extensively. Correlations were examined between individual disease entities and total yield and separated root fractions. A very important and innovative part of the work was to learn about the microbial communities involved in the epidemiology of Verticillium wilt of horseradish roots. The effect was examined of treatment of horseradish cuttings with a biological preparation (Pythium oligandrum), a chemical preparation (thiophanate-methyl), and the Kelpak SL biostimulator (auxins and cytokinins from the Ecklonia maxima algae) on the quantitative and qualitative changes occurring in the communities of these microorganisms. The affiliation of species to groups of frequencies was arranged hierarchically, and the biodiversity of these communities was expressed by the following indicators: Simpson index, Shannon–Wiener index, Shannon evenness index and species richness index. Correlations were assessed between the number of communities, indicators of their biodiversity and intensification of Verticillium wilt of horseradish roots. It was shown that the total yield of horseradish roots was on average 126 dt · ha–1. Within its structure, the main root was 56%, whereas the fraction of lateral roots (cuttings) with a length of more than 20 cm accounted for 26%, and those shorter than 20 cm for 12%, with unprofitable yield (waste) of 6%. In the years with higher humidity, the total root yield was higher than in the dry seasons by around 51 dt · ha–1 on average. On the other hand, the applied protection treatments significantly increased the total yield of horseradish roots from 4,6 to 45,3 dt · ha–1 and the share of fractions of more than 30 cm therein. Higher yielding effects were obtained in variants with a reduced amount of foliar application of fungicides at the expense of introducing biopreparations and biostimulators (R1, R2, R3) and in chemical protection (Ch) than in biological protection (B1, B2) and with the limitation of treatments only to the treatment of cuttings. The largest increments can be expected after treating the seedlings with Topsin M 500 SC and spraying the leaves: 1 × Amistar Opti 480 SC, 1 × Polyversum WP, 1 × Timorex Gold 24 EC and three times with biostimulators (2 × Kelpak SL + 1 × Tytanit). In the perspective of the increasing water deficit, among the biological protection methods, the (B2) variant with the treatment of seedlings with auxins and cytokinins contained in the E. maxima algae extract is more recommended than (B1) involving the use of P. oligandrum spores. White rust was the biggest threat on horseradish plantations, whereas the following occurred to a lesser extent: Phoma leaf spot, Cylindrosporium disease, Alternaria black spot and Verticillium wilt. In turn, on the surface of the roots it was dry root rot and inside – Verticillium wilt of horseradish roots. The best health of the leaves and roots was ensured by full chemical protection (cuttings treatment + 6 foliar applications). A similar effect of protection against Albugo candida and Pyrenopeziza brassicae was achieved in the case of reduced chemical protection to one foliar treatment with synthetic fungicide, two treatments with biological preparations (Polyversum WP and Timorex Gold 24 EC) and three treatments with biostimulators (2 × Kelpak SL, 1 × Tytanit). On the other hand, the level of limitation of root diseases comparable with chemical protection was ensured by its reduced variants R3 and R2, and in the case of dry root rot, also both variants of biological protection. In the dry years, over 60% of the roots showed symptoms of Verticillium wilt, and its main culprits are Verticillium dahliae (37.4%), Globisporangium irregulare (7.2%), Ilyonectria destructans (7.0%), Fusarium acuminatum (6.7%), Rhizoctonia solani (6.0%), Epicoccum nigrum (5.4%), Alternaria brassicae (5.17%). The Kelpak SL biostimulator and the Polyversum WP biological preparation contributed to the increased biodiversity of microbial communities associated with Verticillium wilt of horseradish roots. In turn, along with its increase, the intensification of the disease symptoms decreased. There was a significant correlation between the richness of species in the communities of microbial isolates and the intensification of Verticillium wilt of horseradish roots. Each additional species of microorganism contributed to the reduction of disease intensification by 1,19%.
Book chapters on the topic "Seedling Infection"
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Gomez-Pando, Luz, Jesus Bernardo-Rojas, Denisse Deza-Montoya, Martha Ibañez-Tremolada, and Enrique Aguilar-Castellanos. "Mutation induction to improve quinoa (Chenopodium quinoa) resistance to downy mildew (Peronospora variabilis)." In Mutation breeding, genetic diversity and crop adaptation to climate change. CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0019.
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Abstract Quinoa is an important crop due to its nutritional characteristics (better than cereals) and its tolerance to abiotic stresses. However, various factors such as high susceptibility to diseases, especially downy mildew caused by Peronospora variabilis, limit its agricultural performance. Genetic improvement of quinoa could reduce the need to use fungicides for this crop and maintain the organic quality of Peruvian production in small-scale farms. Seeds of var. 'Amarilla Marangani', irradiated with 150 and 250 Gy of gamma-rays (<sup>60</sup>Co), were evaluated in two experimental locations in Peru: coastland at La Molina and highland at Huancayo. Resistance to downy mildew and other agricultural traits in the M<sub>3</sub> and M<sub>4</sub> generations was studied. In both locations, downy mildew was observed in susceptible plants under natural infection, from the seedling stage to plant maturity. At the coastland site, six mutants with 30% leaf infection were obtained in the progeny of plants exposed to 150 Gy. Five additional mutants with 40% leaf infection were found in the progeny of plants exposed to 250 Gy. In the highland trial, only seven lines were identified with 30% severity (foliar area with symptoms) among the plants from the 150 Gy experiment. The parent materials showed 70-80% disease severity. Mutant lines with quantitative resistance and tolerance to downy mildew, high yield potential, reduced duration, shorter plant height, altered inflorescence shape and grain colour mutations were selected from both doses. This study showed that quantitative resistance and tolerance to downy mildew could be obtained in quinoa and this resulted in increased grain yields.
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Hurek, T., B. Reinhold-Hurek, M. Van Montagu, and E. Kellenberger. "Infection of Intact Roots of Kallar Grass and Rice Seedlings by Azoarcus." In Nitrogen Fixation. Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3486-6_41.
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HAYMAN, D. S. "The Influence of Cottonseed Exudate on Seedling Infection by Rhizoctonia solani." In Root Diseases and Soil-Borne Pathogens. University of California Press, 2023. http://dx.doi.org/10.2307/jj.8501464.23.
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Farhana, Nikhat, Ripudaman M. Singh, Mohammed Gulzar Ahmed, et al. "Seed Biology and Phytochemistry for Sustainable Future." In Seed Biology Updates [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106208.
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The ranking of seeds represents remarkable transition phase for photosynthasis and sexual reproduction, this phase is complex & successful method for sexual reproduction in vascular plants. As we know that seed containe the genetic repository of past & potential for its perpetuation in the future. The dormancy in seeds induced by desciccation & the hormone abscisic acid (ABA) till the condition in growth become favorable. The well developed seeds eliminates requirement of water during sexual reproduction & allows fertilization events to occur over long distances. Germination of seeds in particular situation and season is determines the interaction between dormancy and relating factors like phytochemical development to give healthy bioactives, which strongly influence on the termination of dormancy or initiatin of germination and seedling in many plant species like photo-hormons, light, temperature, water, neutrients and mechanical cuse. Seeds of particular plants needs difreent pretreatment to give vigor seedlings even in production so far. The entiteled chapter represents amulgumation of agriculturists and life scientists. Recent significant progress has been endorsed in seed physiology to solve the practical issues constantly associated with the seeds. The aim & objective of this articale is to enlighten the reader, not only about the different aspects of the seed physiology it also includes the development of bioactive (secondary metabolites) in the healthy seeds. This resorce of pice will help researcher to sencitize about the type of healthy bioactive available in the shalls of seedlings. This could be the reason to isolate the biomolecules from a well evaluate seeds, seed evalution not only the sorce to get healthy crops in agricultural scince it also helps so for a phytochemist to get theuraputicaly active biomolecules, without destroying the nature, which could be the value added thought to combat with the burning issues associated with the existing situation (COVID Omicron, viral infection and all kinds of disorder associated with the immune system). Henceforth, endorsed personage to give real-time attention to plant propagation, particularly for indigenous tree species and seedling multiplication should be regarded as a primary need to make not only a sustainable environment but also become a treasure to fulfill the needs of industry application in the field of agriculture plus R & D.
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Admas, Adugnaw. "Effects of Fusarium Diseases on Forest Nursery and its Controlling Mechanisms." In Fusarium - New Developments in Agriculture [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.1004156.
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Fusarium spp. cause severe harm to forest plants. These fungi can induce latent infections that lead to planted seedlings rooting, as well as pre- and post-emergence damping. However, a phylogenetic study suggests that the most virulent strains of Fusarium oxysporum Schlechtend, which has been identified as the primary cause of root and root rot in nurseries, are more closely aligned with the recently identified Fusarium genus, Skovgaard, O’Donnell, and Nirenberg. Before planting, soil fumigation was the primary method of treating Fusarium illnesses in nurseries with bare roots. Alternative therapies are being investigated as rules impede the supply of the most effective fumigants. This entails improving sanitation, preserving a healthy microbial population that inhibits pathogens infecting trees through their roots, and refraining against actions that increase the risk of disease in trees, such as overfertilization and inadequate soil drainage. Although Fusarium circinatum, Nirenberg, and O’Donnell can be problematic in nurseries, they can harm ancient trees in native forests, plantations, seed farms, and landscape plantings. It is not advisable to transfer seeds or seedlings from contaminated to uninfected areas because they can spread the virus. To stop F. circinatum from spreading to nations where it has not yet been discovered, quarantine measures must be upheld. F. circinatum infections are linked to harm from weather-related events, insect activity, pruning, and seed harvesting, among other forest management practices. Pruning during the cold, dry season, when conditions are less conducive to infection, can help minimize the risk of illness in managed plantations and control insects that have the potential to be vectors and pests. Ecologically friendly biological strategies, such as using endophytic fungi and bacteria that are antagonistic to F. circinatum, plant essential oils, chitosan, or phosphite, have also been researched as ways to lessen the impact. Additionally, to reduce the number of contaminated seeds introduced into nurseries in disease-free areas, heat treatment is an easy and affordable way to eradicate the pathogen from contaminated seeds. Therefore, to address the problems of Fusarium spp,effects on nurseries, natural forests, and plantations using integrated approaches is required for sustainable managements of the forests.
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Afzal, Sadia, Adeela Haroon, Muhammad Arshad Hussain, et al. "Potential of Trichoderma Isolates to Control Plant Pathogen, Leaf Rust on Different Commercial Wheat Varieties/Genotypes." In Wheat. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106387.
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The efficiency in the treatment of leaf rust of wheat was examined for the plant leaf extracts of neem and Moringa at varied concentrations of 50, 100, and 150 ml correspondingly. All treatments decreased fungal growth in vitro by greater than 90%. The germination of spores was decreased by 91.99% in the presence of neem leaf extract at 150 ml concentration. The percentage of pustules/leaf was reduced by foliar spray of the same treatments on seedlings of the wheat plant. The wheat plants show the greatest response against the pathogen of leaf rust by plant extract second foliar application on the fourth day of infection. Spray application of 150 ml, 100 mL of neem leaf extracts, and 150 ml of Moringa leaf extracts at wheat seedlings and rust development completely prevented four days after leaf rust inoculation. The application of treatments of all extracts on wheat plants at the mature stage significantly reduced the disease (ACI, average infection coefficient) and increased the efficacy of plant extract application as compared with control but neem 150 ml treatment was most effective in all. There was a higher increase of the chlorophyll and phenol content in wheat plants.
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Saif, Magdi Ismaiel. "Relationship Between Fruit Tree Growth Conditions in Orchards and the Attack by Nematodes." In Advances in Environmental Engineering and Green Technologies. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-8083-0.ch006.
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The variation in different fruit plant groups morphologically, anatomically, and physiologically beside its type in addition to the preferred place of cultivation all make a difference in the response to the infection by nematodes. In addition, the conditions in the orchard around the fruit plants affect the infection by nematodes. Some plant fruits are big trees (pears), but others are small (grapes). Some of them have a woody stem and others don't (banana). Deciduous fruits can grow in a cold climate, but evergreen fruits grow in a worm places. Orchards of pome and stone fruits are found in cold areas, but bananas grow in hot places and need a lot of water while olives prefer sandy soil with small amounts of water. The nematodes could be affected, and the amount could be decreased in sunny places with the decrease of water and by using mulch. Starting with clean and healthy seedlings or by grafting on tolerated rootstocks could minimize the nematode infection in orchards.
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Sulistiono, Wawan, and Taryono. "The Role of Mycorrhizae on Seedlings and Early Growth of Sugarcane." In Mycorrhizal Fungi - Utilization in Agriculture and Industry [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94768.
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The role of mycorrhizae in plant growth is well known, such as the ability to increase nutrient uptake, especially phosphate (P), drought tolerance, and resistance to pathogens. It is necessary to understand the application of arbuscular mycorrhizal technology in industrial plant production systems and their impact on agriculture systems. Large-scale nurseries of plantations require proper mycorrhizal application techniques. The relationship of mycorrhizal infection with plant yield (biomass) is known and in the next step, appropriate application time is needed to increase the effectiveness of mycorrhizae in plant growth and yield. Application of mycorrhizal inoculum was more effective in increasing the biomass of sugarcane stem weight to reach 61% with an increase in infection of 41.3%. In addition, the mycorrhizal application increases the root growth of sugarcane seedlings. The root growth promoting ability is important to increase the initial growth of plants after transplanting in dry land under the influence of drought stress, limited nutrients. The application of this technology is expected to increase plant growth, facilitate the maintenance and efficiency of cultivation on an industrial scale.
Conference papers on the topic "Seedling Infection"
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Kongtragoul, Pornprapa, and Sansanee Pantakan. "ZINC OXIDE NANOPARTICLES INHIBIT SOME FUNGAL PATHOGENS INFECTION ON DURIAN SEEDLINGS." In SGEM International Multidisciplinary Scientific GeoConference 24. STEF92 Technology, 2024. https://doi.org/10.5593/sgem2024/6.1/s24.17.
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Durian disease-causing organisms such as fungi can infect durian trees at any stage of development. Chemical fungicides are widely used because they are convenient and simple to use. However, it impacts the health of producers, consumers, and the environment. As a result, recommendations have been developed and established for researching zinc oxide nanoparticles (Zn-ONPs) that can inhibit fungal growth as an alternative for preventing and eliminating such fungi. The purpose of this study is to collect and isolate some fungi that cause durian diseases and their pathogenicity test, as well as to investigate the efficacy of Zn-ONPs ranging in size from 25 to 50 nm in inhibiting germination and fungal infection on durian seedlings. Three isolates of Phytophthora sp. (CL4_F1, CL4_S5, CL4_F10), two isolates of Fusarium sp. (CL6_FL1, CL6_FL2), two isolates of Phomopsis sp. (CH1_PF1, CH1_PF2), and two isolates of Rhizoctonia sp. (CL1_RL1, CL1_RL2) were successfully isolated as durian pathogenic fungi. All isolates were pathogenic on durian seedlings, with a 100% disease incidence. As a result, it was found that increasing the concentration of ZnO-NPs could further inhibit growth in the germination and infection of durian seedlings. All tested isolates had delayed germination by ZnO-NPs at all concentrations. Furthermore, as the severity of the disease decreased, ZnO-NPs could inhibit infection in durian seedlings at higher concentrations.
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Kazakova, O. V., L. A. Lomovatskaya, and A. M. Goncharova. "Effect of hydrogen peroxide on the activity of adenylatecyclase signaling components system of cells of the growth zones of root of pea seedling by infection of pathogenic or mutualistic microorganisms." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-244.
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Zamorzaeva, Irina, and Aighiuni Bahşiev. "Lack of stolbur transmission by seeds in some moldavian tomato and pepper varieties." In International Scientific Symposium "Plant Protection – Achievements and Prospects". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2020. http://dx.doi.org/10.53040/9789975347204.86.
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The study of the possibility of stolbur transmission by seeds in some Moldavian tomato and pepper varieties was carried out using molecular diagnostic methods. The lack of the transmission of phytoplasma by seeds was evidenced analysing seedlings growing in the controlled laboratory conditions (thermostat) when the infection by insect vectors was impossible. Moreover, this lack was confirmed by results showing the absence of ‘Ca. P. solani’ infection in plants analyzed in mid-July of 2020 (stages of ‘flowering’ or, mainly, ‘green fruits’) grown in the field or greenhouse.
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Merkel, K. A., and E. P. Vibe. "THE PREVALENCE OF INFECTIOUS LODGING OF SEEDLINGS OF COMMON PINE IN AUTUMN SOWING AT THE NURSERY OF SFNR" ERTIS ORMANY»." In STATE AND DEVELOPMENT PROSPECTS OF AGRIBUSINESS Volume 2. DSTU-Print, 2020. http://dx.doi.org/10.23947/interagro.2020.2.38-40.
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Phytopathological studies of the state of shoots of common pine (Pinus sylvestris L.) of autumn sowing when grown in protected soil with the use of Agrotex covering material were carried out. The results of survey showed that when using fertilizers and soil activators-nitrogen, phosphorus, boric acid, EM EKO KZ Soil, EM EKO KZ soil (NPK) and humus, there is a drop in seedlings from 7.5 to 32.6%. The main reason for the death of shoots was the development and spread of infectious pathogens of seedlings. The species composition of pathogenic microflora in diseased plants is represented by a group of soil fungi belonging to the anamorphic division-Fusarium, Alternaria. Evaluation of the experience of introducing substances into the soil during autumn sowing showed that their use, as a rule, does not affect the resistance of plants to infectious pathogens, with the exception of boric acid, which has fungicidal activity.
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"Cross-adaptation of wheat seedlings under hyperthermia and infection with Bipolaris sorokiniana Shoem." In AGRICULTURAL INFORMATION TECHNOLOGY AND ENGINEERING AGROINFO-2021. SFSCA RAS, 2021. http://dx.doi.org/10.26898/agroinfo-2021-60-64.
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PIMOKHOVA, Lyudmila, German YaGOVENKO, Zhanna TSARAPNEVA, and Nina Kharaborkina. "Impact of efficient protective chemicals on seeds yield of white lupin." In Multifunctional adaptive feed production 27 (75). Federal Williams Research Center of Forage Production and Agroecology, 2022. http://dx.doi.org/10.33814/mak-2022-27-75-65-72.
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The white lupin is a source for qualitative plant protein to provide balanced nutrition for animals and poultry. Seed and green mass yield of modern lupin varieties can be 3–5 t/ha and 70–120 t/ha respectively. In spite of valuable qualities the production crop use is insufficient. One of the reasons is infection by diseases and pests. Anthracnose is the main dangerous and harmfulness disease. As a result lupin is in dire need for high effective protective chemicals. High effectiveness (97–96%) of seed dressers Vitaros – 2.0 l/t, Maxim XL – 2.0 l/t, Divident Star – 0.5 l/t, Selest Top – 0.7 l/t, Inshurperform – 0.7 l/t was revealed against seeds’ infection with anthracnose and other diseases under field conditions. The fungicides Amistar Extra – 0.5 l/ha, Spirit – 0.7 l/ha, Rakurs – 0.4 l/ha, Kolosal Pro – 0.4 l/ha, Bamper Super – 1.5 l/ha and Zantara – 1.5 l/ha are of high effectiveness (88–93%) for protection of lupin crops. The insecticides Tabu – 0.4 l/t and Selest Top – 07 l/t were high effective (76.2–96.0%) against seedlings pests. The most effective dressers (91–96%) against aphids and weevils were the chemicals BI-58 New – 0.7 l/ha and Borey Neo – 0.2 l/ha. The use of the mentioned chemicals for white lupin protection allows manage development and harmfulness level of harmful organisms in crops and prevent significant grain yield losses.
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Şcerbacova, Tatiana. "Trichoderma fungi for plant protection from Albifimbria verrucaria (Myrothecium)." In Scientific International Symposium “Advanced Biotechnologies - Achievements and Prospects” (VIth Edition). Institute of Genetics, Physiology and Plant Protection, 2022. http://dx.doi.org/10.53040/abap6.2022.76.
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Fungi Albifimbria verrucaria (Alb. et Schwein.) L.Lombard et Crous (2016) is known as Myrothecium verrucaria (Alb. et Schwein.) Ditmar (1813). Recently, Myrothecium was assig-ned to Stachybotriaceae family, Ascomycotha phylum, and called Albifimbria [1]. Fungi of Albifimbria (Myrothecium) Tode ex Fries genus are widely distributed in nature as phytopathogens and can damage all parts of plants. On the leaves, pathogenicity manifests itself in the form of spots. Water ulcers may form on the stems. On solid fruits (aubergine, cucumber), spots and constrictions are formed, and the fruits acquire an ugly shape. On juicy fruits (tomato), ulcers form the fruit cracks and it rots. Rots may develop on the roots. Seed infection causes pre-germinative and post-germinative death of seedlings, stem rot, death of the growth point, and root ulcers [2]. Albifimbria phytopathogens are producers of harmful macrocyclic trichothecene myco-toxins of the verrucarin series. Under favorable weather conditions (high humidity and tempe-rature), they contaminate stubble crops and grassy pastures. After grazing animals on infected substrates, the development of myrotheciotoxicosis may occur. Horses, cattle, and sheep get sick. [3]. To protect plants from Alb.verrucaria fungus damage, it is advisable to search for fungi-antagonists that are producers of microbiological preparations. The present research aims to select strains of Trichoderma fungi that are promising for protecting plants from the toxin-pro-ducing pathogen Albifimbria verrucaria.
Reports on the topic "Seedling Infection"
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Ward, Kimiora. Sierra Nevada Network high elevation white pine monitoring: 2021 annual report. National Park Service, 2024. http://dx.doi.org/10.36967/2302327.
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Five-needle white pines (Family Pinaceae, Genus Pinus, Subgenus Strobus), and in particular whitebark pine (Pinus albicaulis), limber pine (P. flexilis), and foxtail pine (P. balfouriana) are foundation species in upper subalpine and treeline forests of several National Park Service Pacific West Region parks, including Sequoia and Kings Canyon National Parks (SEKI) and Yosemite National Park (YOSE). The Sierra Nevada Network Inventory & Monitoring Program, in collaboration with the Klamath Network, Upper Columbia Basin Network, and Mojave Desert Network have implemented a joint long-term monitoring protocol to assess the current status and future trends in high elevation white pine communities. Key demographic parameters within white pine forest communities will be estimated by monitoring individual trees within permanent plots through time. This report documents the results of the 2021 field season, which was the eighth year of monitoring in Sequoia and Kings Canyon National Parks (SEKI) and Yosemite National Park (YOSE). The 2021 goal was to complete the third full re-measure of the second of three rotating panels (Panel 2) for each species-park population: YOSE-whitebark pine, SEKI-whitebark pine, and SEKI-foxtail pine. Each panel consists of 12 permanent 50 x 50 m (2,500 m2) plots that were randomly selected for each of the three populations. The full sampling array thus includes a total of 36 whitebark pine plots in YOSE, 36 whitebark pine plots in SEKI, and 36 foxtail pine plots in SEKI. Data from plot surveys will be used to characterize white pine forest community dynamics in SEKI and YOSE, including changes in tree species composition, forest structure, forest health, and demographics. The first full measure of all Panel 2 plots was completed over two years in 2013-2014, then a full remeasure of both parks? whitebark pine Panel 2 was conducted in 2016, with 10 of 12 SEKI-foxtail plots sampled that year. A third remeasure of all Panel 2 plots was not possible in 2021 because a smaller crew size was necessary during the COVID-19 pandemic. In total, the crew visited 37 sites, and sampled 31, during the 2021 field season. One plot in the YOSE whitebark pine frame was uninstalled before reading and one plot in the SEKI whitebark pine frame was uninstalled after reading, both for safety concerns. Four plots were not visited due to lack of capacity with the reduced crew size: one in each of the YOSE and SEKI whitebark frames, and three in the SEKI foxtail frame. A plot from Panel 3 in each of the parks? whitebark frames was measured, for a total of 11 plots measured in each whitebark pine frame. Nine plots were measured in the SEKI foxtail pine frame. Within the 31 plots completed, a total of 5,728 trees was measured. Species composition, forest structure, and factors affecting tree health and reproduction, including incidence and severity of white pine blister rust (Cronartium ribicola) infection, mountain pine beetle (Dendroctonus ponderosae) infestation, dwarf mistletoe (Arceuthobium spp.) infection, canopy kill, female cone production and regeneration were recorded. During the 2021 field season, crews continued to count the total number of mature cones per tree for whitebark and foxtail pine, use crown condition codes to assess crown health, and tag individual seedlings to be tracked through time. All three of these procedures started in 2017 and are to be evaluated by each of the three participating networks over several years, to determine whether they should become permanent changes to the monitoring protocol. In YOSE, 11 whitebark pine plots were re-measured, from Panels 2 and 3. A total of 2,810 trees were sampled, which included 586 live whitebark pine trees and 2,097 other live conifers. An additional 127 trees (including 17 whitebark pine) were recorded as dead. The forest crew noted little sign of white pine blister rust (WPBR) in Yosemite in 2021, and just a single inactive canker was observed on one whitebark pine in Panel 3, Plot 42, near Dana Meadows. This infection was new to plot 42, and it expands the total number of plots where white pine blister rust has been documented in Yosemite to six. The crew also noted little mountain pine beetle activity, documenting beetle galleries on 15 lodgepole pines in three Panel 2 plots. Dwarf mistletoe was not observed. The average number of live whitebark pine trees per plot was 53 (SD = 56). This was a low cone crop year for whitebark pine, with two percent of live whitebark pine trees producing female cones. Cone bearing trees averaged 2 (SD = 1) cones per tree. Whitebark pine seedling density averaged 90 (SD = 157) seedlings per hectare. The largest number of whitebark pine seedlings found in a plot was four, and three of the eleven plots contained whitebark seedlings. In SEKI, 10 of 12 Panel 2, and one Panel 3, whitebark pine plots were re-measured. Within these plots, 1,246 live whitebark pine, 30 live foxtail pine, and 861 other live conifers were sampled. WPBR was infrequently documented in the SEKI whitebark frame as well, with indicators of infection in Plot 31 near Window Creek and Plot 44 near Upper State Lake. These were the first infections documented in these plots, bringing the number of plots where WPBR has been documented in the SEKI whitebark panel to nine. Although WPBR was documented in Plot 27 near Charlotte Dome in 2016, it was not documented this year because putative cankers showing three signs of infection in 2016 showed only two or fewer signs in 2021. Mountain pine beetle activity was observed in one live lodgepole pine and two recently dead whitebark pine, within three plots in the SEKI whitebark sample frame. An exception to the low levels of mountain pine beetle activity was outside Plot 31 in the Window Creek area, where the forest crew noted many recently dead whitebark pine with signs of beetle activity. Dwarf mistletoe was not encountered. The average number of live whitebark pine trees per plot was 113 (SD = 86). Less than one percent of live whitebark pine trees produced female cones, each producing on average 2 (SD = 1) cones. Whitebark seedling regeneration averaged 303 (SD = 319) seedlings per hectare. The largest number of whitebark seedlings found in a plot was eight, and eight of the 11 plots contained whitebark seedlings. Nine of the 12 SEKI foxtail Panel 3 plots were remeasured. Within these plots, 413 live foxtail pine, 67 live whitebark pine, and 402 other live conifers were sampled. Ninety-two dead or recently dead trees were also documented, 65 of which were foxtail pine. No signs of blister rust infection, mistletoe, or mountain pine beetle were observed in the foxtail plots sampled. The average number of foxtail pine trees per plot was 46 (SD = 33). Fifty-four percent of the foxtail pine trees produced female cones, averaging 14 (SD =15) cones/tree. Only one foxtail pine seedling was recorded within the 9 foxtail pine plots, resulting in an estimated 14 (SD = 41) seedlings per hectare. Eight whitebark pine seedlings were also found within two plots.
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Ward, Kimiora. Sierra Nevada Network white pine monitoring: 2022 annual report. National Park Service, 2023. http://dx.doi.org/10.36967/2301003.
Full textAbstract:
Five-needle white pines (Family Pinaceae, Genus Pinus, Subgenus Strobus), and in particular whitebark pine (Pinus albicaulis), limber pine (P. flexilis), and foxtail pine (P. balfouriana) are foundation species in upper subalpine and treeline forests of several National Park Service Pacific West Region parks, including Sequoia and Kings Canyon National Parks (SEKI) and Yosemite National Park (YOSE). The Sierra Nevada Network Inventory & Monitoring Program, in collaboration with the Klamath Network, Upper Columbia Basin Network, and Mojave Desert Network have implemented a joint long-term monitoring protocol to assess the current status and future trends in high elevation white pine communities. Key demographic parameters within white pine forest communities will be estimated by monitoring individual trees within permanent plots through time. This report documents the results of the 2022 field season, which was the ninth year of monitoring in SEKI and YOSE. The 2021 goal was to complete the first full measure of the third of three rotating panels (Panel 3) for each species-park population: YOSE-whitebark pine, SEKI-whitebark pine, and SEKI-foxtail pine. Each panel consists of 12 permanent 50 x 50 m (2,500 m2) plots that were randomly selected for each of the three populations. The full sampling array thus includes a total of 36 whitebark pine plots in YOSE, 36 whitebark pine plots in SEKI, and 36 foxtail pine plots in SEKI. Data from plot surveys will be used to characterize white pine forest community dynamics in SEKI and YOSE, including changes in tree species composition, forest structure, forest health, and demographics. Partial measures of Panel 3 were completed in 2017 (11 plots) in Yosemite whitebark pine, in 2017 (9 plots) in SEKI whitebark pine, and in 2014 (7 plots) and 2017-2018 (8, 1 plots) in foxtail pine. In 2022, the first full measure of all Panel 3 plots (and 2nd or 3rd remeasure of most plots) was successfully completed, and installation was completed on four of these plots in SEKI whitebark pine and two in foxtail pine. In total, the crew visited 36 sites during the 2022 field season, all from Panel 3. Within the 36 completed Panel 1 plots, a total of 6,398 trees were measured. Species composition, forest structure, and factors affecting tree health and reproduction including incidence and severity of white pine blister rust (Cronartium ribicola) infection, mountain pine beetle (Dendroctonus ponderosae) infestation, dwarf mistletoe (Arceuthobium spp.) infection, canopy kill, and female cone production were recorded. During the 2022 field season crews continued to count the total number of mature cones per tree for whitebark and foxtail pine, use crown condition codes to assess crown health, and tag individual seedlings to be tracked through time. All three of these procedures started in 2017 and are to be evaluated by each of the three participating networks over several years, to determine whether they should become permanent changes to the monitoring protocol. In YOSE, all 12 Panel 3 whitebark pine plots were measured. A total of 2,720 trees were sampled, which included 977 live whitebark pine trees and 1,605 other live conifers. An additional 135 trees (including 26 whitebark) were recorded as dead. The average number of live whitebark pine trees per plot was 81 (SD = 94). White pine blister rust (WPBR) aecia were observed on five whitebark pine in one plot in YOSE in 2022, and no trees in any plot had inactive cankers showing three or more indicators of WPBR. WPBR had previously been documented in this plot, so the number of plots where rust has ever been observed in Yosemite remains unchanged at six. However, an infection documented in plot 42 in 2021 was not observed again when the plot was resampled in 2022, so it is possible this number should be five. Mountain pine beetle activity was observed on one live whitebark pine and three live and one dead lodgepole pine in YOSE in 2022. Despite documentation of many stands impacted by beetle attack in the field crew notes, the quantified rate of MPB attack was lower than in 2021. Twenty-one percent of live whitebark pine trees produced female cones. Cone-bearing trees averaged 7 (SD = 10) cones/tree. Whitebark pine seedling density averaged 80 (SD = 152) seedlings per hectare. The largest number of whitebark pine seedlings found in a plot was 51 and five of the twelve plots contained whitebark seedlings. All 12 Panel 3 SEKI whitebark pine plots were measured in 2022, and installation was completed on four of these, so this Panel is now fully installed. Within these plots, 2,179 live whitebark pine, 10 live foxtail pine, and 297 other live conifers were sampled (including 5 live western white pine). The average number of live whitebark pine trees per plot was 181 (SD = 125). Although the crew observed white pine blister rust in seven SEKI whitebark Panel 3 plots, no active cankers (aecia) were observed, and no trees displayed 3 of 5 indicators, so no infections were quantified. Mountain pine beetle activity was observed in 18 live and 23 dead whitebark pine and 1 live and one dead lodgepole pine within three plots in SEKI. Dwarf mistletoe was not encountered. Seven percent of live whitebark pine trees produced female cones. Cone-bearing trees averaged 3.7 (SD = 3.6) cones/tree. Whitebark seedling regeneration averaged 700 (SD = 752) seedlings per hectare. The largest number of whitebark seedlings found in a plot was 19, and two of the 12 plots did not contain any whitebark seedlings. In the foxtail pine Panel 3, all 12 plots were measured in 2022, and installation was completed on two of these, so installation of the panel is now complete. Within these plots we measured 309 live foxtail pine, 302 live whitebark pine, and 380 other live conifers, including four live western white pine. An additional 112 dead or recently dead trees and 22 unidentified snags were also measured, 19 of which were foxtail pine. The average number of foxtail pine trees per plot was 26 (SD = 26). No signs of blister rust infection or mistletoe were observed on foxtail pine. Mountain pine beetle activity was observed on one dead foxtail pine, one live whitebark pine, and seven live and one dead lodgepole pines within four plots. Sixty-two percent of the foxtail pine trees produced female cones. Cone-bearing trees averaged 33 (SD = 53) cones/tree. Seven foxtail pine seedlings were recorded within five plots, resulting in an estimated 72 (SD = 98) seedlings per hectare. Eight whitebark pine seedlings and three lodgepole pine seedlings were also found within three additional plots.
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Sela, Hanan, Eduard Akhunov, and Brian J. Steffenson. Population genomics, linkage disequilibrium and association mapping of stripe rust resistance genes in wild emmer wheat, Triticum turgidum ssp. dicoccoides. United States Department of Agriculture, 2014. http://dx.doi.org/10.32747/2014.7598170.bard.
Full textAbstract:
The primary goals of this project were: (1) development of a genetically characterized association panel of wild emmer for high resolution analysis of the genetic basis of complex traits; (2) characterization and mapping of genes and QTL for seedling and adult plant resistance to stripe rust in wild emmer populations; (3) characterization of LD patterns along wild emmer chromosomes; (4) elucidation of the multi-locus genetic structure of wild emmer populations and its correlation with geo-climatic variables at the collection sites. Introduction In recent years, Stripe (yellow) rust (Yr) caused by Pucciniastriiformis f. sp. tritici(PST) has become a major threat to wheat crops in many parts of the world. New races have overcome most of the known resistances. It is essential, therefore, that the search for new genes will continue, followed by their mapping by molecular markers and introgression into the elite varieties by marker-assisted selection (MAS). The reservoir of genes for disease and pest resistance in wild emmer wheat (Triticumdicoccoides) is an important resource that must be made available to wheat breeders. The majority of resistance genes that were introgressed so far in cultivated wheat are resistance (R) genes. These genes, though confering near-immunity from the seedling stage, are often overcome by the pathogen in a short period after being deployed over vast production areas. On the other hand, adult-plant resistance (APR) is usually more durable since it is, in many cases, polygenic and confers partial resistance that may put less selective pressure on the pathogen. In this project, we have screened a collection of 480 wild emmer accessions originating from Israel for APR and seedling resistance to PST. Seedling resistance was tested against one Israeli and 3 North American PST isolates. APR was tested on accessions that did not have seedling resistance. The APR screen was conducted in two fields in Israel and in one field in the USA over 3 years for a total of 11 replicates. We have found about 20 accessions that have moderate stripe rust APR with infection type (IT<5), and about 20 additional accessions that have novel seedling resistance (IT<3). We have genotyped the collection using genotyping by sequencing (GBS) and the 90K SNP chip array. GBS yielded a total 341K SNP that were filtered to 150K informative SNP. The 90K assay resulted in 11K informative SNP. We have conducted a genome-wide association scan (GWAS) and found one significant locus on 6BL ( -log p >5). Two novel loci were found for seedling resistance. Further investigation of the 6BL locus and the effect of Yr36 showed that the 6BL locus and the Yr36 have additive effect and that the presence of favorable alleles of both loci results in reduction of 2 grades in the IT score. To identify alleles conferring adaption to extreme climatic conditions, we have associated the patterns of genomic variation in wild emmer with historic climate data from the accessions’ collection sites. The analysis of population stratification revealed four genetically distinct groups of wild emmer accessions coinciding with their geographic distribution. Partitioning of genomic variance showed that geographic location and climate together explain 43% of SNPs among emmer accessions with 19% of SNPs affected by climatic factors. The top three bioclimatic factors driving SNP distribution were temperature seasonality, precipitation seasonality, and isothermality. Association mapping approaches revealed 57 SNPs associated with these bio-climatic variables. Out of 21 unique genomic regions controlling heading date variation, 10 (~50%) overlapped with SNPs showing significant association with at least one of the three bioclimatic variables. This result suggests that a substantial part of the genomic variation associated with local adaptation in wild emmer is driven by selection acting on loci regulating flowering. Conclusions: Wild emmer can serve as a good source for novel APR and seedling R genes for stripe rust resistance. APR for stripe rust is a complex trait conferred by several loci that may have an additive effect. GWAS is feasible in the wild emmer population, however, its detection power is limited. A panel of wild emmer tagged with more than 150K SNP is available for further GWAS of important traits. The insights gained by the bioclimatic-gentic associations should be taken into consideration when planning conservation strategies.
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Dubcovsky, Jorge, Tzion Fahima, and Ann Blechl. Molecular characterization and deployment of the high-temperature adult plant stripe rust resistance gene Yr36 from wheat. United States Department of Agriculture, 2013. http://dx.doi.org/10.32747/2013.7699860.bard.
Full textAbstract:
Stripe rust, caused by Puccinia striiformis f. sp. tritici is one of the most destructive fungal diseases of wheat. Virulent races that appeared within the last decade caused drastic cuts in yields. The incorporation of genetic resistance against this pathogen is the most cost-effective and environmentally friendly solution to this problem. However, race specific seedling resistance genes provide only a temporary solution because fungal populations rapidly evolve to overcome this type of resistance. In contrast, high temperature adult plant (HTAP) resistance genes provide a broad spectrum resistance that is partial and more durable. The cloning of the first wheat HTAP stripe rust resistance gene Yr36 (Science 2009, 323:1357), funded by our previous (2007-2010) BARD grant, provided us for the first time with an entry point for understanding the mechanism of broad spectrum resistance. Two paralogous copies of this gene are tightly linked at the Yr36 locus (WKS1 and WKS2). The main objectives of the current study were to characterize the Yr36 (WKS) resistance mechanism and to identify and characterize alternative WKSgenes in wheat and wild relatives. We report here that the protein coded by Yr36, designated WKS1, that has a novel architecture with a functional kinase and a lipid binding START domain, is localized to chloroplast. Our results suggest that the presence of the START domain may affect the kinase activity. We have found that the WKS1 was over-expressed on leaf necrosis in wheat transgenic plants. When the isolated WKS1.1 splice variant transcript was transformed into susceptible wheat it conferred resistance to stripe rust, but the truncated variant WKS1.2 did not confer resistance. WKS1.1 and WKS1.2 showed different lipid binding profiling. WKS1.1 enters the chloroplast membrane, while WKS1.2 is only attached outside of the chloroplast membrane. The ascorbate peroxidase (APX) activity of the recombinant protein of TmtAPXwas found to be reduced by WKS1.1 protein in vitro. The WKS1.1 mature protein in the chloroplast is able to phosphorylate TmtAPXprotein in vivo. WKS1.1 induced cell death by suppressing APX activity and reducing the ability of the cell to detoxify reactive oxygen. The decrease of APX activity reduces the ability of the plant to detoxify the reactive H2O2 and is the possible mechanism underlying the accelerated cell death observed in the transgenic plants overexpressing WKS1.1 and in the regions surrounding a stripe rust infection in the wheat plants carrying the natural WKS1.1 gene. WKS2 is a nonfunctional paralog of WKS1 in wild emmer wheat, probably due to a retrotransposon insertion close to the alternative splicing site. In some other wild relatives of wheat, such as Aegilops comosa, there is only one copy of this gene, highly similar to WKS2, which is lucking the retrotransposon insertion. WKS2 gene present in wheat and WKS2-Ae from A. showed a different pattern of alternative splice variants, regardless of the presence of the retrotransposon insertion. Susceptible Bobwhite transformed with WKS2-Ae (without retrotansposon insertion in intron10), which derived from Aegilops comosaconferred resistance to stripe rust in wheat. The expression of WKS2-Ae in transgenic plants is up-regulated by temperature and pathogen infection. Combination of WKS1 and WKS2-Ae shows improved stripe rust resistance in WKS1×WKS2-Ae F1 hybrid plants. The obtained results show that WKS1 protein is accelerating programmed cell death observed in the regions surrounding a stripe rust infection in the wheat plants carrying the natural or transgenic WKS1 gene. Furthermore, characterization of the epistatic interactions of Yr36 and Yr18 demonstrated that these two genes have additive effects and can therefore be combined to increase partial resistance to this devastating pathogen of wheat. These achievements may have a broad impact on wheat breeding efforts attempting to protect wheat yields against one of the most devastating wheat pathogen.
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Davis, Eric L., Yuji Oka, Amit Gal-On, Todd Wehner, and Aaron Zelcer. Broad-spectrum Resistance to Root-Knot Nematodes in Transgenic Cucurbits. United States Department of Agriculture, 2013. http://dx.doi.org/10.32747/2013.7593389.bard.
Full textAbstract:
Root-knot nematodes (RKN), Meloidogyne spp., are extremely destructive pathogens of cucurbit crops grown in the United States and Israel. The safety and environmental concerns of toxic nematicides, and limited sources of natural cucurbit resistance to the four major species of Meloidogyne that threaten these crops in Israel and the U.S., have emphasized the use of biotechnology to develop cucurbits with novel RKN resistance. The U.S. scientists have identified over 40 unique RKN parasitism genes that encode nematode secretions involved in successful plant root infection by RKN, and they have demonstrated that expression of a double-stranded RNA (dsRNA) complementary to a RKN parasitism gene (called 16DIO) in Arabidopsis thaliana induced RNA interference (RNAi)-mediated silencing of the RKN16DlO gene and produced transgenic plants with strong resistance to all four major RKN species. The expression 8D05 parasitism gene was found to coincide with the timing of upregulation of NtCel7 promoter (identified to be upregulated in giantcells by US scientists). NtCel7 promoter was used to express the genes at the right time (early stages of infection) and in the right place (giant-cells) in transgenic plants. US partners produced NtCel7 (nematode-induced promoter)-driven 16DlO-RNAi and 8DOS-RNAi constructs, pHANNIBAL 4D03-RNAi construct and modified 16DlO-RNAi construct (for increased RNAi expression and efficacy) for cucurbit transformation in Israel. In Arabidopsis, some 16DlO-RNAi plant lines show greater levels of resistance to M. incognita than others, and within these lines resistance of greater than 90% reduction in infection is observed among almost all replicates in US. The level of observed nematode resistance is likely to be directly correlated with the level of RNAi expression in individual plants. In Israel, all the RKN parasitism genes-RNAi constructs were successfully transformed into cucumber and melon. The transgenic lines were evaluated for expression of the transgene siRNA in leaves and roots. Those displaying transgene siRNA accumulation were passed on for nematode resistance analysis. Rl seedlings from different lines were subjected to evaluation for resistance to M. javanica. None of the lines was resistant to the nematode in contrast with US partner's results in Arabidopsis. This could be for the following reasons: a) The level of transgene siRNA was insufficient in cucumber and tomato to cause resislance. b) 111e nemalode species on cucwnber IIlay be different ur act in a different manner. c) The assay was performed in soil with a high level of nematode inoculation, and not in petri dish, which may not permit the observation of a low level of resistance.
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Phillips, Donald, and Yoram Kapulnik. Using Flavonoids to Control in vitro Development of Vesicular Arbuscular Mycorrhizal Fungi. United States Department of Agriculture, 1995. http://dx.doi.org/10.32747/1995.7613012.bard.
Full textAbstract:
Vesicular-arbuscular mycorrhizal (VAM) fungi and other beneficial rhizosphere microorganisms, such as Rhizobium bacteria, must locate and infect a host plant before either symbiont profits. Although benefits of the VAM association for increased phosphorous uptake have been widely documented, attempts to improve the fungus and to produce agronomically useful amounts of inoculum have failed due to a lack of in vitro production methods. This project was designed to extend our prior observation that the alfalfa flavonoid quercetin promoted spore germination and hyphal growth of VAM fungi in the absence of a host plant. On the Israeli side of the project, a detailed examination of changes in flavonoids and flavonoid-biosynthetic enzymes during the early stages of VAM development in alfalfa found that VAM fungi elicited and then suppressed transcription of a plant gene coding for chalcone isomerase, which normally is associated with pathogenic infections. US workers collaborated in the identification of flavonoid compounds that appeared during VAM development. On the US side, an in vitro system for testing the effects of plant compounds on fungal spore germination and hyphal growth was developed for use, and intensive analyses of natural products released from alfalfa seedlings grown in the presence and absence of microorganisms were conducted. Two betaines, trigonelline and stachydrine, were identified as being released from alfalfa seeds in much higher concentrations than flavonoids, and these compounds functioned as transcriptional signals to another alfalfa microsymbiont, Rhizobium meliloti. However, these betaines had no effect on VAM spore germination or hyphal growth i vitro. Experiments showed that symbiotic bacteria elicited exudation of the isoflavonoids medicarpin and coumestrol from legume roots, but neither compound promoted growth or germination of VAM fungi in vitro. Attempts to look directly in alfalfa rhizosphere soil for microbiologically active plant products measured a gradient of nod-gene-inducing activity in R. meliloti, but no novel compounds were identified for testing in the VAM fungal system in vitro. Israeli field experiments on agricultural applications of VAM were very successful and developed methods for using VAM to overcome stunting in peanuts and garlic grown in Israel. In addition, deleterious effects of soil solarization on growth of onion, carrot and wheat were linked to effects on VAM fungi. A collaborative combination of basic and applied approaches toward enhancing the agronomic benefits of VAM asociations produced new knowledge on symbiotic biology and successful methods for using VAM inocula under field conditions
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Minz, Dror, Eric Nelson, and Yitzhak Hadar. Ecology of seed-colonizing microbial communities: influence of soil and plant factors and implications for rhizosphere microbiology. United States Department of Agriculture, 2008. http://dx.doi.org/10.32747/2008.7587728.bard.
Full textAbstract:
Original objectives: Our initial project objectives were to 1) Determine and compare the composition of seed-colonizing microbial communities on seeds, 2) Determine the dynamics of development of microbial communities on seeds, and 3) Determine and compare the composition of seed-colonizing microbial communities with the composition of those in the soil and rhizosphere of the plants. Revisions to objectives: Our initial work on this project was hampered by the presence of native Pythium species in the soils we were using (in the US), preventing us from getting accurate assessments of spermosphere microbial communities. In our initial work, we tried to get around this problem by focusing on water potentials that might reduce damage from native Pythium species. This also prompted some initial investigation of the oomycete communities associated seedlings in this soil. However, for this work to proceed in a way that would allow us to examine seed-colonizing communities on healthy plants, we needed to either physically treat soils or amend soils with composts to suppress damage from Pythium. In the end, we followed the compost amendment line of investigation, which took us away from our initial objectives, but led to interesting work focusing on seed-associated microbial communities and their functional significance to seed-infecting pathogens. Work done in Israel was using suppressive compost amended potting mix throughout the study and did not have such problems. Our work focused on the following objectives: 1) to determine whether different plant species support a microbial induced suppression of Pythium damping-off, 2) to determine whether compost microbes that colonize seeds during early stages of seed germination can adequately explain levels of damping-off suppression observed, 3) to characterize cucumber seed-colonizing microbial communities that give rise to the disease suppressive properties, 4) assess carbon competition between seed-colonizing microbes and Pythium sporangia as a means of explaining Pythium damping-off suppression. Background: Earlier work demonstrated that seed-colonizing microbes might explain Pythium suppression. Yet these seed-colonizing microbial communities have never been characterized and their functional significance to Pythium damping-off suppression is not known. Our work set out to confirm the disease suppressive properties of seed-colonizing microbes, to characterize communities, and begin to determine the mechanisms by which Pythium suppression occurs. Major Conclusions: Compost-induced suppression of Pythium damping-off of cucumber and wheat can be explained by the bacterial consortia colonizing seeds within 8 h of sowing. Suppression on pea was highly variable. Fungi and archaea play no role in disease suppression. Potentially significant bacterial taxa are those with affinities to Firmicutes, Actinobacteria, and Bacteroidetes. Current sequencing efforts are trying to resolve these taxa. Seed colonizing bacteria suppress Pythium by carbon competition, allowing sporangium germination by preventing the development of germ tubes. Presence of Pythium had a strong effect on microbial community on the seed.