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1
Isutsa, D. K., I. A. Merwin, and B. B. Brodie. "Screening Malus Germplasm for Field Resistance to Apple Replant Disease and Root-lesion Nematodes." HortScience 31, no. 4 (August 1996): 618f—618. http://dx.doi.org/10.21273/hortsci.31.4.618f.
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Apple replant disease (ARD) is a serious problem in fruit production, and none of the major clonal rootstocks are resistant to ARD. We have screened Malus domestica clones and species accessions from the USDA Malus Germplasm Repository at Geneva, N.Y., including M. angustifolia-2375.03 (MA), M. coronaria-2966.01 (MC), M. fusca-3031.01 (MF), M. ioensis-3059.01 (MI), M. sieversii-3530.01 (MS), and M. kirghisorum-3578.01 (MK), for resistance to ARD and root-lesion nematodes (RLN, Pratylenchus spp.), in a composite soil collected from 11 New York orchards with known ARD. Plant dry mass and height, root necrosis, and nematode populations in different apple species and clones were compared after 60 days growth in steam-pasteurized (PS), RLN-inoculated (IS), and naturally infested field (FS) soils with 1200 RLN per 100 cm3. More severe stunting, reduced plant dry mass, and root necrosis occurred in FS seedlings compared with those in PS, but M. angustifolia seedlings were substantially more resistant or tolerant to RLN and ARD than the other species tested. Plant dry mass ranked MK>MS>MA>MI>MF>MC, and these differences were significant at the 5% level. RLN root populations were negatively correlated with plant dry mass, and accounted for about 10% of its variation, with nematode populations in roots ranking MC>MF>MK>MI>MS>MA. Useful resistance to ARD and parasitic nematodes apparently exists within Malus germplasm collections, and can be identified by testing more genotypes, developing rapid resistance screening methods, and comparing RLN host preferences among Malus genotypes and various orchard cover crops.
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Vieira, Paulo, and Lev G. Nemchinov. "An Expansin-Like Candidate Effector Protein from Pratylenchus penetrans Modulates Immune Responses in Nicotiana benthamiana." Phytopathology® 110, no. 3 (March 2020): 684–93. http://dx.doi.org/10.1094/phyto-09-19-0336-r.
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The root lesion nematode (RLN) Pratylenchus penetrans is a migratory species that attacks a broad range of crops. After the RLN is initially attracted to host roots by root exudates and compounds, it releases secretions that are critical for successful parasitism. Among those secretions are nematode virulence factors or effectors that facilitate the entry and migration of nematodes through the roots and modulate plant immune defenses. The recognition of the effectors by host resistance proteins leads to effector-triggered immunity and incompatible plant–nematode interactions. Although many candidate effectors of the RLN and other plant-parasitic nematodes have been identified, the detailed mechanisms of their functions and particularly, their host targets remain largely unexplored. In this study, we sequenced and annotated genes encoding expansin-like proteins, which are major candidate effectors of P. penetrans. One of the genes, Pp-EXPB1, which was the most highly expressed during nematode infection in different plant species, was further functionally characterized via transient expression in the model plant Nicotiana benthamiana and global transcriptome profiling of gene expression changes triggered by this candidate effector in plants. As a result of this investigation, the biological roles of Pp-EXPB1 in nematode parasitism were proposed, the putative cellular targets of the proteins were identified, and the molecular mechanisms of plant responses to the nematode-secreted proteins were outlined.
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Walters, Thomas W., John N. Pinkerton, Ekaterini Riga, Inga A. Zasada, Michael Particka, Harvey A. Yoshida, and Chris Ishida. "Managing Plant–Parasitic Nematodes in Established Red Raspberry Fields." HortTechnology 19, no. 4 (January 2009): 762–68. http://dx.doi.org/10.21273/hortsci.19.4.762.
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The efficacy and phytotoxicity of postplant treatments to control root lesion nematodes [RLN (Pratylenchus penetrans)] and dagger nematodes [DN (Xiphinema bakeri)] in red raspberry (Rubus idaeus) were evaluated in four field studies, each conducted over 1 to 3 years. Spring spray applications of oxamyl or fosthiazate reduced RLN and DN population densities for up to 2 years, but fall oxamyl sprays and spring drip-applied oxamyl applications were not effective. Oxamyl application rate determined the duration of nematode suppression. Two spring applications of oxamyl at 2 lb/acre provided more than 2 years of suppression, while two spring applications of 0.8 lb/acre suppressed nematodes for only 1 year. Spring oxamyl applications reduced ‘Nootka’ fruit yield for one season, but did not affect ‘Willamette’ yield. Fall spray-applied fenamiphos, fall and spring spray-applied DiTera (a fermentation product of the fungus Myrothecium verrucaria), fall drip-applied 1,3-dichloropropene, and spring shallow-incorporated abyssinian mustard (Brassica carinata) seed meal suppressed RLN briefly (less than 6 months) or not at all.
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Walters, Thomas W., John N. Pinkerton, Ekaterini Riga, Inga A. Zasada, Michael Particka, Harvey A. Yoshida, and Chris Ishida. "Managing Plant–Parasitic Nematodes in Established Red Raspberry Fields." HortTechnology 19, no. 4 (January 2009): 762–68. http://dx.doi.org/10.21273/horttech.19.4.762.
Full textAbstract:
The efficacy and phytotoxicity of postplant treatments to control root lesion nematodes [RLN (Pratylenchus penetrans)] and dagger nematodes [DN (Xiphinema bakeri)] in red raspberry (Rubus idaeus) were evaluated in four field studies, each conducted over 1 to 3 years. Spring spray applications of oxamyl or fosthiazate reduced RLN and DN population densities for up to 2 years, but fall oxamyl sprays and spring drip-applied oxamyl applications were not effective. Oxamyl application rate determined the duration of nematode suppression. Two spring applications of oxamyl at 2 lb/acre provided more than 2 years of suppression, while two spring applications of 0.8 lb/acre suppressed nematodes for only 1 year. Spring oxamyl applications reduced ‘Nootka’ fruit yield for one season, but did not affect ‘Willamette’ yield. Fall spray-applied fenamiphos, fall and spring spray-applied DiTera (a fermentation product of the fungus Myrothecium verrucaria), fall drip-applied 1,3-dichloropropene, and spring shallow-incorporated abyssinian mustard (Brassica carinata) seed meal suppressed RLN briefly (less than 6 months) or not at all.
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Kumar, Ashish, Vedant Gautam, R. K. Tiwari, Stuti Sharma, Jayant Bhatt, Radheshyam Sharma, and R. Shiv RamaKrishnan. "Present status and future directions for management of root lesion nematode (Pratylenchus thornei) in chickpea." Environment Conservation Journal 23, no. 1&2 (May 23, 2022): 400–409. http://dx.doi.org/10.36953/ecj.0211204.2337.
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Chickpea is a popular legume crop in Asia and Africa's semi-arid regions. Crop production gains, on the other hand, have been modest, owing to biotic and abiotic stressors. Among the different biotic stresses, nematodes portray serious threat to chickpea production and colossal losses have been reported due to stress-free infection by other pathogens on infection with root lesion nematode (RLN). The worldwide distribution of two major species of RLN namely P. thornei and P. neglectus made them a focus research area especially on management aspect. In dryland farming areas of southeastern Australia, the P. thornei alone can cause yield losses of up to 40% in cereals and legumes. Despite the fact that chickpea breeders have been working persistently to generate superior chickpea varieties with increased resilience or tolerance to biotic and abiotic challenges, contemporary biotechnology technologies can help to speed up this process. To incorporate these tools and/or accelerate breeding programmes, identification of RLN resistant source with its genetic factor is first step in developing improved cultivars. However, study of resistance screening methods for chickpea against RLN is limited and standardization of different factors for development of a stable screening methodology distinguishing various levels of resistance is the need of the hour in RLN research.
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Barbosa, Pedro, Jorge M. S. Faria, Tomás Cavaco, Ana Cristina Figueiredo, Manuel Mota, and Cláudia S. L. Vicente. "Nematicidal Activity of Phytochemicals against the Root-Lesion Nematode Pratylenchus penetrans." Plants 13, no. 5 (March 4, 2024): 726. http://dx.doi.org/10.3390/plants13050726.
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Plant-parasitic nematodes (PPNs) are highly damaging pests responsible for heavy losses in worldwide productivity in a significant number of important plant crops. Common pest management strategies rely on the use of synthetic chemical nematicides, which have led to serious concerns regarding their impacts on human health and the environment. Plant natural products, or phytochemicals, can provide a good source of agents for sustainable control of PPNs, due to their intrinsic characteristics such as higher biodegradability, generally low toxicity for mammals, and lower bioaccumulation in the environment. In this work, the nematicidal activity of 39 phytochemicals was determined against the root-lesion nematode (RLN) Pratylenchus penetrans using standard direct and indirect contact methodologies. Overall, the RLN was tolerant to the tested phytochemicals at the highest concentration, 2 mg/mL, seldom reaching full mortality. However, high activities were obtained for benzaldehyde, carvacrol, 3-octanol, and thymol, in comparison to other phytochemicals or the synthetic nematicide oxamyl. These phytochemicals were seen to damage nematode internal tissues but not its cuticle shape. Also, the environmental and (eco)toxicological parameters reported for these compounds suggest lower toxicity and higher safety of use than oxamyl. These compounds appear to be good candidates for the development of biopesticides for a more sustainable pest management strategy.
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Isutsa, Dorcas, Ian Merwin, and Bill Brodie. "Evaluating Transgenic Apple for Resistance or Tolerance to Apple Replant Disease." HortScience 33, no. 3 (June 1998): 531d—531. http://dx.doi.org/10.21273/hortsci.33.3.531d.
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Apple replant disease (ARD) causes serious problems in most fruit-growing regions worldwide. It is associated with nematodes, fungi, bacteria, and other deleterious factors. Its symptoms range from severe stunting to death of replants in old orchards. We evaluated effects of antibacterial (cecropin-, attacin- and hen egg white lysozyme-encoding) and antifungal (chitinase-encoding) transgenics, obtained from the apple-rootstock breeding program at Geneva, N.Y., on ARD. Transgenics were tested in a composite soil collected from New York orchards with known replant problems. The ARD-infested field soil (FS) had ≈675 Pratylenchus penetrans (root-lesion nematodes, RLN) and ≈75 Xiphinema americanum (dagger nematodes) per liter pot; soil for controls was steam-pasteurized. Height, biomass, nematode vermiforms and eggs were recorded after ≈60 days under optimal growing conditions in the greenhouse. There was significant variation in growth and Pratylenchus counts among transgenics (P < 0.00), most of which were susceptible to ARD. However, endoparasitic RLN accounted for <50% of the variation in biomass, suggesting that other factors were important in affecting plants. Conversely, RLN significantly increased root necrosis (P < 0.00; R2 = 80%). Eggs were observed in diseased chitinase-encoding lines, probably because of low-gene expression. There was no significant difference in eggs among the lines (P ≤ 0.3). Apparently, good growth was inconsistent and due to confounding factors such as mild ARD. These results suggest that single-gene therapy and low-gene expression may not protect apple against ARD complex, instead gene-pyramiding and high-gene expression should be tested.
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Reeves, Karyn L., Clayton R. Forknall, Alison M. Kelly, Kirsty J. Owen, Joshua Fanning, Grant J. Hollaway, and Robert Loughman. "A Novel Approach to the Design and Analysis of Field Experiments to Study Variation in the Tolerance and Resistance of Cultivars to Root Lesion Nematodes (Pratylenchus spp.)." Phytopathology® 110, no. 10 (October 2020): 1623–31. http://dx.doi.org/10.1094/phyto-03-20-0077-r.
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The root lesion nematode (RLN) species Pratylenchus thornei and P. neglectus are widely distributed within cropping regions of Australia and have been shown to limit grain production. Field experiments conducted to compare the performance of cultivars in the presence of RLNs investigate management options for growers by identifying cultivars with resistance, by limiting nematode reproduction, and tolerance, by yielding well in the presence of nematodes. A novel experimental design approach for RLN experiments is proposed where the observed RLN density, measured prior to sowing, is used to condition the randomization of cultivars to field plots. This approach ensured that all cultivars were exposed to consistent ranges of RLN in order to derive valid assessments of relative cultivar tolerance and resistance. Using data from a field experiment designed using the conditioned randomization approach and conducted in Formartin, Australia, the analysis of tolerance and resistance was undertaken in a linear mixed model framework. Yield response curves were derived using a random regression approach and curves modeling change in RLN densities between sowing and harvest were derived using splines to account for nonlinearity. Groups of cultivars sharing similar resistance levels could be identified. A comparison of slopes of yield response curves of cultivars belonging to the same resistance class identified differing tolerance levels for cultivars with equivalent exposures to both presowing and postharvest RLN densities. As such, the proposed design and analysis approach allowed tolerance to be assessed independently of resistance.
9
Toktay, Halil, C. Lynne McIntyre, Julie M. Nicol, Hakan Ozkan, and Halil I. Elekcioglu. "Identification of common root-lesion nematode (Pratylenchus thornei Sher et Allen) loci in bread wheat." Genome 49, no. 10 (October 2006): 1319–23. http://dx.doi.org/10.1139/g06-090.
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Plant parasitic nematodes are a major biotic cause of wheat-yield loss in temperate wheat-growing regions. A major strategy to develop resistance to root-lesion nematodes (RLNs) in wheat is to assess and then exploit their natural genetic variation. This study examines RLN (Pratylenchus thornei) resistance in 1 Middle Eastern landrace (AUS4930 7.2) and 1 synthetic hexaploid wheat, CROC_1/AE.SQUARROSA (224)//OPATA (CROC), using F2 and F9 populations generated by crossing AUS4930 7.2 and CROC with the susceptible cultivar Pastor, and inoculating these crosses with P. thornei in greenhouse trials. Wheat microsatellite markers linked to previously identified quantitative trait loci (QTLs) for resistance to P. thornei and P. neglectus were used to screen both populations. In the AUS4930 7.2 × Pastor population, resistance loci on chromosomes 1B, 2B, and 6D were detected. Similarly, in the CROC × Pastor population, 2 resistance loci, located on chromosomes 1B and 3B, were identified. Interestingly, a resistance locus located on chromosome 6D was not detected. More detailed mapping is required in these 2 populations, developed using new RLN resistance sources, to determine whether the QTLs identified on these chromosomes are the same, are allelic, or are linked to different resistance loci from those previously identified, and to determine whether these 2 sources contain other novel resistance loci.
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Keçici, Ayça İrem, Refik Bozbuğa, Atilla Öcal, Ebubekir Yüksel, Göksel Özer, Şenol Yildiz, Rachid Lahlali, Brigitte Slaats, Abdelfattah A. Dababat, and Mustafa İmren. "Diversity and Identification of Plant-Parasitic Nematodes in Wheat-Growing Ecosystems." Microorganisms 10, no. 8 (July 29, 2022): 1534. http://dx.doi.org/10.3390/microorganisms10081534.
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Several nematode species can be found in different densities in almost any soil ecosystem, and their diversity in those ecosystems depends on numerous reasons, such as climatic conditions and host presence. Cereals are one of the main hosts of plant-parasitic nematodes (PPN), chiefly root-lesion nematodes (RLN, Pratylenchus spp.) and cereal cyst nematodes (CCN, Heterodera spp.). These nematodes are known as major parasites of the cereal crops; however, agricultural areas accommodate various nematodes showing biological variation. The diversity of parasitic nematodes on cereals in the Sakarya provinces of Türkiye, where cereals are intensively grown and located in the middle of two climatic zones, has not been well studied. Therefore, in this study, we aimed to determine the diversity, identification, and molecular phylogeny of PPNs in wheat-growing ecosystems in the Hendek, Pamukova, Geyve, Akyazı, and Central districts of Sakarya. The diversity of PPNs was calculated using the Shannon diversity index. Thirteen PPN genera were detected in 92% of soil samples. Heterodera filipjevi was identified in 24% of the soil samples using morphological, morphometrical, and molecular tools. In the morphological and molecular analyses, intraspecific polymorphism was observed in H. filipjevi populations. The result indicated that the high infestation rate of H. filipjevi was recorded from Geyve and Pamukova, followed by Hendek and Akyazı; however, a low infestation rate was detected in the Central district. The moderate value of the Shannon index of migratory nematode species was obtained in wheat fields as 2.31, whereas the value of evenness was 0.93, implying moderate diversity and high evenness of nematodes. This study is the first comprehensive report on H. filipjevi from wheat cropping areas in the Sakarya province. Intensified cereal cropping systems with/without non-cereal rotations increased the risk of plant-parasitic nematodes, especially RLNs and H. filipjevi infection of wheat production areas in the province.
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Reen, R. A., J. P. Thompson, T. G. Clewett, J. G. Sheedy, and K. L. Bell. "Yield response in chickpea cultivars and wheat following crop rotations affecting population densities of Pratylenchus thornei and arbuscular mycorrhizal fungi." Crop and Pasture Science 65, no. 5 (2014): 428. http://dx.doi.org/10.1071/cp13441.
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In Australia, root-lesion nematode (RLN; Pratylenchus thornei) significantly reduces chickpea and wheat yields. Yield losses from RLN have been determined through use of nematicide; however, nematicide does not control nematodes in Vertosol subsoils in Australia’s northern grains region. The alternative strategy of assessing yield response, by using crop rotation with resistant and susceptible crops to manipulate nematode populations, is poorly documented for chickpea. Our research tested the effectiveness of crop rotation and nematicide against P. thornei populations for assessing yield loss in chickpea. First-year field plots included canola, linseed, canaryseed, wheat and a fallow treatment, all with and without the nematicide aldicarb. The following year, aldicarb was reapplied and plots were re-cropped with four chickpea cultivars and one intolerant wheat cultivar. Highest P. thornei populations were after wheat, at 0.45–0.6 m soil depth. Aldicarb was effective to just 0.3 m for wheat and 0.45 m for other crops, and increased subsequent crop grain yield by only 6%. Canola, linseed and fallow treatments reduced P. thornei populations, but low mycorrhizal spore levels in the soil after canola and fallow treatments were associated with low chickpea yield. Canaryseed kept P. thornei populations low throughout the soil profile and maintained mycorrhizal spore densities, resulting in grain yield increases of up to 25% for chickpea cultivars and 55% for wheat when pre-cropped with canaryseed compared with wheat. Tolerance indices for chickpeas based on yield differences after paired wheat and canaryseed plots ranged from 80% for cv. Tyson to 95% for cv. Lasseter and this strategy is recommended for future use in assessing tolerance.
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Isutsa, Dorcas K., and Ian A. Merwin. "Malus Germplasm Varies in Resistance or Tolerance to Apple Replant Disease in a Mixture of New York Orchard Soils." HortScience 35, no. 2 (April 2000): 262–68. http://dx.doi.org/10.21273/hortsci.35.2.262.
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We tested 40 seedling lots and 17 clonal accessions—representing 941 genotypes and 19 species or interspecific hybrids of Malus—for their resistance or tolerance to apple replant disease (ARD) in a mixture of five New York soils with known replant problems. Total plant biomass, root necrosis, root-infesting fungi, and root-lesion nematode (RLN; Pratylenchus penetrans Cobb) or dagger nematode (DN; Xiphinema americanum Cobb) populations were evaluated in apple seedlings and clones grown for ≈60 days in the composite soil. In addition to phytophagous nematodes, various Pythium, Cylindrocarpon, Fusarium, Rhizoctonia and Phytophthora species were isolated from roots grown in the test soil. Plant growth response was categorized by a relative biomass index (RBI), calculated as total plant dry weight in the pasteurized field soil (PS) minus that in an unpasteurized field soil (FS), divided by PS. Nematode reproduction on each genotype was defined by a relative reproduction index (RRI), calculated as final nematode populations in roots and soil (Pf) minus initial soil populations (Pi), divided by Pi. The RBI, RRI, and other responses of accessions to ARD soil were used to rate their resistance, tolerance, or susceptibility to apple replant disease. None of the accessions was completely resistant to ARD pathogens in our test soil. Seedling accessions of M. sieversii Roem. and M. kirghisorum Ponom. appeared to have some tolerance to ARD, based upon their low RRIs and RBIs. Three clonal rootstock accessions (G.65, CG.6210, and G.30), and four other clones (M. baccata Borkh.—1883.h, M. xanthocarpa Langenf.—Xan, M. spectabilis Borkh.— PI589404, and M. mandshurica Schneid.—364.s) were categorized as tolerant to ARD. The disease response of other accessions was rated as susceptible or too variable to classify. We concluded that sources of genetic tolerance to ARD exist in Malus germplasm collections and could be used in breeding and selecting clonal rootstocks for improved control of orchard replant pathogens.
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Everts, K. L., S. Sardanelli, R. J. Kratochvil, D. K. Armentrout, and L. E. Gallagher. "Root-Knot and Root-Lesion Nematode Suppression by Cover Crops, Poultry Litter, and Poultry Litter Compost." Plant Disease 90, no. 4 (April 2006): 487–92. http://dx.doi.org/10.1094/pd-90-0487.
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Experiments using soil-incorporated cover crops and amendments of poultry litter (PL) and PL compost to suppress root-knot (RKN) and root-lesion nematodes were conducted in response to increasing nematode populations in Maryland's potato production areas. Identical experiments were established in microplots infested with Meloidogyne incognita or Pratylenchus penetrans. Treatments consisted of 12 3-year rotational sequences comprising potato (year 1) and cucumber (year 2) followed by a moderately RKN-resistant or susceptible soybean cultivar, castor bean, grain sorghum, or sorghum sudangrass; PL or PL compost were amended to some of the RKN-susceptible soybean and sorghum sudangrass plots. In the third year of the rotation, potato followed by soybean was planted in all 12 treatments. The RKN-resistant soybean, castor bean, sorghum sudangrass, and fallow or tillage decreased the populations of M. incognita compared with microplots where RKN-susceptible soybean had been grown. However, RKN populations quickly recovered. Root-lesion nematode was reduced in the spring of 2001 following application of high rates of PL and PL compost in 2000. In the fall of 2001, sorghum sudangrass alone or in combination with PL or PL compost, grain sorghum, or fallow or tillage reduced root-lesion nematodes compared with either soybean cultivar. No treatment affected root-lesion nematode the following year. The use of cover crops and PL compost is an effective method to reduce nematode populations only if successively incorporated into rotational cropping sequences.
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Zasada, Inga A., Thomas W. Walters, and John N. Pinkerton. "Post-Plant Nematicides for the Control of Root Lesion Nematode in Red Raspberry." HortTechnology 20, no. 5 (October 2010): 856–62. http://dx.doi.org/10.21273/horttech.20.5.856.
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To identify a post-plant nematicide to control root lesion nematode [RLN (Pratylenchus penetrans)] in red raspberry (Rubus idaeus), a number of nematicides was tested in soil-only and plant-based experiments. In soil-only experiments, soil naturally infested with RLN was drenched with the nematicides and nematode survival was assessed 7 and 14 days after treatment. Fosthiazate and oxamyl reduced RLN recovery 92% and 52% across trials and sampling times, respectively, compared with the nontreated control. Other nematicides that resulted in moderate, and sometimes inconsistent, control of RLN were soapbark (Quillaja saponaria) saponins, 1,3-dichloropropene, and methomyl. In plant-based experiments, ‘Meeker’ red raspberry was established in pots with RLN-infested soil mixed with greenhouse soil and the nematicides were applied as soil drenches or as a foliar application. Nematode recovery and cane and root weights were quantified as measurements of nematicide toxicity and phytotoxicity, respectively. Similar to soil-only experiments, fosthiazate and oxamyl were the most effective nematicides tested in reducing RLN population densities in established red raspberry. Fosthiazate and oxamyl significantly reduced RLN per gram dry root population densities by 97% and 87%, respectively, compared with the infested, nontreated control. None of the other nematicides reduced RLN population densities compared with the infested, nontreated controls. There was no phytotoxicity to red raspberry associated with any of the nematicides.
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Lopes-Caitar, Valéria Stefania, Rafael Bruno Guayato Nomura, Suellen Mika Hishinuma-Silva, Mayra Costa da Cruz Gallo de Carvalho, Ricardo Vilela Abdelnoor, Waldir Pereira Dias, and Francismar Corrêa Marcelino-Guimarães. "Time Course RNA-seq Reveals Soybean Responses against Root-Lesion Nematode and Resistance Players." Plants 11, no. 21 (November 4, 2022): 2983. http://dx.doi.org/10.3390/plants11212983.
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Pratylenchus brachyurus causes serious damage to soybean production and other crops worldwide. Plant molecular responses to RLN infection remain largely unknown and no resistance genes have been identified in soybean. In this study, we analyzed molecular responses to RLN infection in moderately resistant BRSGO (Chapadões—BRS) and susceptible TMG115 RR (TMG) Glycine max genotypes. Differential expression analysis revealed two stages of response to RLN infection and a set of differentially expressed genes (DEGs) in the first stage suggested a pattern-triggered immunity (PTI) in both genotypes. The divergent time-point of DEGs between genotypes was observed four days post-infection, which included the activation of mitogen-activated protein kinase (MAPK) and plant–pathogen interaction genes in the BRS, suggesting the occurrence of an effector-triggered immunity response (ETI) in BRS. The co-expression analyses combined with single nucleotide polymorphism (SNP) uncovered a key element, a transcription factor phytochrome-interacting factor (PIF7) that is a potential regulator of moderate resistance to RLN infection. Two genes for resistance-related leucine-rich repeat (LRR) proteins were found as BRS-specific expressed genes. In addition, alternative splicing analysis revealed an intron retention in a myo-inositol oxygenase (MIOX) transcript, a gene related to susceptibility, may cause a loss of function in BRS.
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Rudolph, Rachel E., Thomas W. Walters, Lisa W. DeVetter, and Inga A. Zasada. "Contribution of a Winter Wheat Cover Crop to the Maintenance of Root Lesion Nematode Populations in the Red Raspberry Production System." HortTechnology 28, no. 2 (April 2018): 182–88. http://dx.doi.org/10.21273/horttech03971-18.
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One of the primary production challenges red raspberry (Rubus idaeus) growers in the Pacific northwestern United States confront is root lesion nematode [RLN (Pratylenchus penetrans)]. In this perennial production system, red raspberry serves as a sustained host for RLN. When a red raspberry planting is slated for removal in the fall, a new red raspberry planting quickly follows in the same field the following spring. The primary crop that occurs in rotation with red raspberry is a winter wheat cover crop to provide soil coverage and protection during the winter. The objectives of this research were to determine if winter wheat (Triticum aestivum) provides a green bridge for RLN in continuous red raspberry production systems and to determine if modified winter cover cropping practices can be used to reduce population densities of RLN before replanting red raspberry. Four trials were established in fields being replanted to red raspberry and the following modified winter cover cropping practices were considered: cover crop planting date (at fumigation or 2 weeks after fumigation), termination date (cover crop kill with herbicide 2 or 6 weeks before incorporation compared with the industry standard of incorporation immediately before planting), and the additional application of methomyl. ‘Rosalyn’ and ‘Bobtail’ winter wheat planted as cover crops in these trials were demonstrated to be maintenance hosts for RLN (ranging from 10 to 947 RLN/g winter wheat root across trials) allowing them to be a green bridge for RLN to infect the following red raspberry crop. Altering winter wheat cover crop planting date, termination date with herbicide, or methomyl application did not affect RLN population densities in the subsequent red raspberry crop. Although planting an RLN maintenance host may be of concern to growers, the advantages of reduced soil erosion and nitrate leaching associated with cover cropping outweigh the perceived risk to the subsequent red raspberry crop.
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Zheng, Xia, Siyuan Zhu, Shouwei Tang, and Touming Liu. "Identification of drought, cadmium and root-lesion nematode infection stress-responsive transcription factors in ramie." Open Life Sciences 11, no. 1 (January 1, 2016): 191–99. http://dx.doi.org/10.1515/biol-2016-0025.
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AbstractDrought, cadmium (Cd) stress, and root lesion nematode (RLN) infection are three of the most important stresses affecting ramie growth and development; therefore, ramie breeding programs focus on their management more than on any other abiotic or biotic stresses. The fact that only a small number of stress-responsive transcription factors (TFs) have been identified so far is a major obstacle in the elucidation of mechanisms regulating the response to these three stresses in ramie. In this study, in order to uncover more stress-responsive TFs, a total of 179 nonredundant genes with full-length open reading frames from the MYB, AP2/ERF, bZIP, HD-ZIP, and COL families were obtained by searching for against the ramie transcriptome. Expression pattern analysis demonstrated that most of these genes showed relatively higher expression in the stem xylem and bast than in other tissues. Among these genes, 96 genes were found to be involved in responses to drought, Cd exposure, or RLN-infection. The expression of 54 of these genes was regulated by at least two stresses. These stress-responsive TFs probably have roles in the regulation of stress tolerance. The discovery of these stress-responsive TFs will be helpful for furthering our understanding of the mechanisms that regulate stress responses in ramie.
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Ogbonnaya, F. C., M. Imtiaz, H. S. Bariana, M. McLean, M. M. Shankar, G. J. Hollaway, R. M. Trethowan, E. S. Lagudah, and M. van Ginkel. "Mining synthetic hexaploids for multiple disease resistance to improve bread wheat." Australian Journal of Agricultural Research 59, no. 5 (2008): 421. http://dx.doi.org/10.1071/ar07227.
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A collection of 253 synthetic hexaploid wheats (SHWs) produced from 192 Aegilops tauschii accessions and 39 elite durum varieties were studied to identify, characterise, and evaluate potentially untapped diversity of disease resistance in wheat. The diseases for which resistance was sought included cereal cyst nematode (CCN), root lesion nematode (RLN), Stagonospora nodorum blotch (SNB), Septoria tritici blotch (STB), and the 3 rusts, leaf rust, stem rust, and stripe rust, all important diseases of bread wheat worldwide, which can severely reduce wheat yield and quality. The SHWs exhibited a wide spectrum of resistance to the 8 pathogens. The frequency of disease-resistant SHWs ranged from 1% for one species of RLN (Pratylenchus neglectus), 3% and 10% for Septoria nodorum leaf and glume blotch, 10% for seedling resistance to yellow leaf spot, 16% for CCN, 21% for the second species of RLN (Pratylenchus thornei), 73% for Septoria tritici blotch, and 15%, 40%, and 24% for leaf rust, stem rust, and stripe rust, respectively. Five SHWs, Aus26860, Aus30258, Aus30294, Aus30301, and Aus30304, exhibited high levels of resistance to CCN, YLP, STB, LR, and SR, while 56 SHWs showed resistance to either 3 or 4 diseases. The genetics of resistance to CCN in some of the SHWs revealed that some of the accessions carry the same CCN gene(s) against pathotype Ha13, while others may carry different resistance gene(s). Additional studies were carried out to understand the relationship between the resistances identified in SHWs and the ones already present in common wheat, in particular the resistance genes Cre1 and Cre3 against CCN. The use of perfect markers associated with Cre1 and Cre3 suggested that some SHWs may carry a new CCN resistance gene(s), which could be deployed in breeding programs to increase the diversity of available resistance. The identification of SHWs with resistance to a range of diseases provides an opportunity to generate genetic knowledge and resistant germplasm to be used in future variety development.
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Tolba, Shimaa R. T., Laura C. Rosso, Isabella Pentimone, Mariantonietta Colagiero, Mahmoud M. A. Moustafa, Ibrahim I. S. Elshawaf, Giovanni Bubici, Maria Isabella Prigigallo, and Aurelio Ciancio. "Root Endophytism by Pochonia chlamydosporia Affects Defense-Gene Expression in Leaves of Monocot and Dicot Hosts under Multiple Biotic Interactions." Plants 10, no. 4 (April 7, 2021): 718. http://dx.doi.org/10.3390/plants10040718.
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A study was carried out on the effect of the root endophytic fungus Pochonia chlamydosporia on plant systemic signal of defense related genes during fungal or nematode parasitism. Different biotic stress factors were examined, inoculating roots of dicot and monocot hosts with the endophyte, and measuring the expression of defense genes in leaves. A first greenhouse assay was carried out on expression of PAL, PIN II, PR1 and LOX D in leaves of tomato cv Tondino inoculated with Phytophthora infestans (CBS 120920), inoculating or not the roots of infected plants with P. chlamydosporia DSM 26985. In a second assay, plants of banana (Musa acuminata cv Grand Naine) were artificially infected with Fusarium oxysporum f. sp. cubense Tropical race 4 (TR4) and inoculated or not with DSM 26985. In a further experiment, banana plants were inoculated or not with P. chlamydosporia plus juveniles of the root knot nematode (RKN) Meloidogyne incognita. A similar assay was also carried out in vitro with adults and juveniles of the lesion nematode Pratylenchus goodeyi. Differential expression of the defense genes examined was observed for all plant-stress associations, indicative of early, upward systemic signals induced by the endophyte. Changes in expression profiles included a 5-fold down-regulation of PIN II at 2 dai in leaves of tomato plants treated with P. infestans and/or P. chlamydosporia, and the up-regulation of PAL by the endophyte alone, at 2 and 7 dai. In the TR4 assay, PR1 was significantly up-regulated at 7 dai in banana leaves, but only in the P. chlamydosporia treated plants. At 10 dai, PIN II expression was significantly higher in leaves of plants inoculated only with TR4. The banana-RKN assay showed a PR1 expression significantly higher than controls at 4 and 7 dai in plants inoculated with P. chlamydosporia alone, and a down-regulation at 4 dai in leaves of plants also inoculated with RKN, with a PR1 differential up-regulation at 10 dai. Pratylenchus goodeyi down-regulated PIN at 21 dai, with or without the endophyte, as well as PAL but only in presence of P. chlamydosporia. When inoculated alone, the endophyte up-regulated PR1 and LOX. The gene expression patterns observed in leaves suggest specific and time-dependent relationships linking host plants and P. chlamydosporia in presence of biotic stress factors, functional to a systemic, although complex, activation of defense genes.
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Fatemi, Ehsan, Siegbert Melzer, and Christian Jung. "DNA-based assessment of root lesion nematode infections in cereal roots." Scientific Reports 13, no. 1 (August 3, 2023). http://dx.doi.org/10.1038/s41598-023-39559-8.
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AbstractRoot lesion nematodes (RLN) of the genus Pratylenchus are causing significant damage in cereal production worldwide. Due to climate change and without efficient and environment-friendly treatments, the damages through RLNs are predicted to increase. Microscopic assessments of RLNs in the field and the greenhouses are time-consuming and laborious. As a result, cereal breeders have mostly ignored this pest. We present a method measuring RLN in infected cereal roots using a standardized PCR approach. Publicly available Pratylenchus neglectus primer combinations were evaluated. An optimal primer combination for RT-qPCR assay was identified to detect and quantify P. neglectus within infected cereal roots. Using the RT-qPCR detection assay, P. neglectus could be clearly distinguished from other plant parasitic nematodes. We could identify P. neglectus DNA in barley and wheat roots as low as 0.863 and 0.916 ng/µl of total DNA, respectively. A single P. neglectus individual was detected in water suspension and within barley and wheat roots. The RT-qPCR detection assay provides a robust and accurate alternative to microscopic nematode identification and quantification. It could be of interest for resistance breeding, where large populations must be screened to detect and quantify P. neglectus in farmer’s fields.
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Xia, Yanhui, Jing Li, Penghui Hao, Ke Wang, Bin Lei, Hong-Lian Li, and YU Li. "Discovery of Root-Lesion Nematode (Pratylenchus scribneri) on Corn in Hainan Province of China." Plant Disease, November 24, 2021. http://dx.doi.org/10.1094/pdis-09-21-1960-pdn.
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Corn (Zea mays L.) is a very important cereal crop and serves as food, feed, and industrial material (Liu et al. 2016). The root-lesion nematode (RLN) is considered one of the most important plant-parasitic nematodes and can cause economic losses in agriculture worldwide (Jones et al. 2013). In January 2020, five samples were collected from a corn field in Lingshui Lizu Autonomous County, Hainan Province, China. The collected corn plants (cv. Denghai 685) were growing poorly and roots showed distinct lesions and rot. Corn fields with symptoms of stunted plants, and brown lesions on roots were widespread. This corn disease was severe in Lingshui Lizu Autonomous County. RLN were extracted from soil samples by the modified Baermann funnel (Hooper et al. 2005). All the samples contained RLN ranging from 9 to 82 (average 39) RLN per 100 cm3 of soil and 113 to 257 (average 194) RLN per 5 g roots. The extracted RLN were sterilized and cultured on carrot disks at 25°C for 90 days. Afterwards, seeds of corn (cv. Denghai 685) were sown in pots containing 1.8 liters of sterilized soil. Eight plants, one per pot, were infested with 1,000 RLN, eight pots of noninfested corn plants were used as controls, and plants were kept in a greenhouse at 25°C. At 75 days after inoculation, symptoms were like those initially observed in corn fields, whereas no symptoms were observed in the control plants. Nematodes in the soil and roots were extracted using the same method as previously described (Hooper et al. 2005). The average number of RLN per pot was approximately 4,250 in soil and 820 in roots, the reproduction factor (final number of nematodes/initial number of nematodes) was 5.07, no RLN were found in the control. The experiment was conducted twice. The morphological and molecular studies of RLN were examined to confirm species identification. The main morphological measurements of adult females (n = 15) included body length = 526.0 μm ± 17.1 (standard error) (range = 498.0 to 560.5 μm), stylet = 16.0 μm ± 0.3 (15.5 to 16.5 μm), tail length = 29.0 μm ± 1.5 (26.5 to 31.0 μm), a = 23.6 ± 0.6 (22.6 to 24.4), b = 5.6 ± 0.3 (5.2 to 6.0), c = 18.3 ± 0.9 (16.4 to 19.7), V = 78.2% ± 0.6 (77.4 to 79.2%), lip region with two annules. No males were found in the samples. This population was identified as Pratylenchus scribneri, based on the morphological characters (Castillo and Vovlas, 2007). DNA was isolated from individual nematodes followed by proteinase K-based lysis (Wang et al. 2011). The D2/D3 expansion region of the 28S rRNA gene, rDNA-internal transcribed spacer (ITS) region, and mitochondrial cytochrome oxidase I (mtDNA-COI) gene were amplified with primers D2A/-D3B (De Ley et al. 1999), TW81/ AB28 (Vovlas et al. 2011) and JB3/ JB5 (Liu et al. 2018), respectively. The PCR products were purified and ligated into pJET 1.2/blunt cloning vectors and transformed to Escherichia coli strain DH5α, and then sequenced. The obtained 28S rRNA gene D2/D3 region sequences (785bp), ITS sequences (886 bp) and mtDNA-COI (447bp) in this study were submitted to GenBank. The D2/D3 region of the 28S rRNA sequences of the RLN collected in Lingshui (GenBank accession no. MZ701843) showed 99.75% identity with P. scribneri sequences available in the GenBank (KX842628 and KX842625). The ITS sequences of the RLN collected in this study (MZ701842) showed the highest identity of 97.06% with P. scribneri sequences available in the GenBank (KX842626). The mtDNA-COI sequences of the RLN collected in this study (OK040228) showed 100% identity with P. scribneri (MN366409). Both morphological and molecular data confirmed the identity of P. scribneri. P. scribneri has been reported on corn in Inner Mongolia, Hebei, Shanxi, Shandong, Henan, Jiangsu, and Liaoning provinces of China (Li et al. 2019). As far as we know, this is the first report of P. scribneri on corn in Hainan Province, China. Since the RLN can cause considerable damage to corn, strategic measures should be taken to prevent the spread of P. scribneri to other regions in China.
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Qi, Xiuxiu, Xia Xue, Guoquan Su, Yanlai Han, Yi Wang, Yu Li, and Ying Jiang. "The physiological and biochemical role of silicon in enhancing the resistance of maize to root‐lesion nematode." Plant Pathology, June 17, 2024. http://dx.doi.org/10.1111/ppa.13955.
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AbstractSilicon (Si) plays an important role in enhancing the tolerance of plants to biotic and abiotic stress in soil ecosystems. Root‐lesion nematodes (Pratylenchus scribneri; RLNs) cause root damage and diseases that result in quality deterioration and economic loss. This study investigated the effects of Si application on maize plants and its interaction with RLN infection. We set up different treatments to evaluate the role of silicon application in maize root growth and RLN resistance. This study conducted analysis by combining measurements of the metabolism and root activity of maize under different conditions. The results suggested that Si application (0.5 g/kg) significantly promoted fresh shoot weight, plant height, SPAD value (chlorophyll content), and root activity of maize, regardless of RLN inoculation. The highest SPAD value was observed in the Si treatment, which was significantly higher than in the control (CK) and RLN (N) treatments. Analysis of enzyme activity revealed that nematode inoculation reduced catalase (CAT) activity and increased malondialdehyde (MDA) concentration, while Si application increased CAT activity and decreased MDA concentration. In the SiN treatment, there was increased CAT activity at 0, 12, 48, 72 and 96 h compared with the N treatment. In parallel, nematode inoculation increased phenylalanine ammonia‐lyase (PAL), and polyphenol oxidase (PPO) activities, while SiN treatment further enhanced their activities. These findings indicate that Si application enhances maize resistance to nematode infection and improves plant growth and antioxidant defence mechanisms.
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Li, Yu, Jin Li, Yaojun Hu, Ke Wang, Hongxia Yuan, Bingjian Sun, Hong-Lian Li, and Bin Lei. "Occurrence of Root-Lesion Nematode Pratylenchus coffeae on Corn in Xinjiang Uygur Autonomous Region, China." Plant Disease, April 22, 2022. http://dx.doi.org/10.1094/pdis-09-21-1988-pdn.
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Pratylenchus coffeae Filipjev & Schuurmans Stekhoven, 1941, is one of the most important root-lesion nematodes (RLN) parasitizing many agronomic and industrial crops (Wang et al. 2021). Corn (Zea mays L.) is one economically important crop in China, with 35 million hectares cultivated annually (Li et al. 2019). In July 2019, a survey of RLN was carried out in corn field planting with cultivar Heyu 187 in Chuanba village in Qitai County, Xinjiang Uygur Autonomous Region, China. Five root/soil samples were collected from poor growing plants with distinct brown lesions. Nematodes were extracted from the collected root/soil samples with the modified Baermann funnel method (Hooper et al. 2005). The average of 157 RLN per 100 cm3 of soil and 43 RLN per gram of fresh root were extracted. The obtained RLN were sterilized with 0.3% streptomycin sulfate and cultured on carrot disks at 25°C. Twenty petri dishes with carrot disks, each inoculated with one female. The morphological and molecular characteristics of RLN cultured on carrot disks were examined for species identification. Morphological measurements of adult females (n=15) included body length (range = 529.0 to 658.0 μm, mean = 571.0 μm), head with two lip annuli, stylet (15.5 to 17.0 μm, 16.0 μm), tail length (27.5 to 32.5 μm, 30.5 μm), a (23.8 to 32.9, 28.5), b (5.8 to 7.1, 6.5), c (16.5 to 23.4, 18.9), and V (76.6 to 83.1%, 80.8%). Morphological measurements of adult males (n=15) were body length (range = 479.5 to 568.0 μm, mean = 516.0 μm), head with two lip annuli, stylet (14.5 to 15.5 μm, 15.0 μm), tail length (24.0 to 29.0 μm, 26.0 μm), spicule length (16.4 to 19.0 μm, 17.5 μm), gubernaculum length (4.4 to 5.3 μm, 4.9 μm), a (29.2 to 32.5, 31.0), b (5.7 to 6.9, 6.2), and c (18.2 to 22.6, 19.8). The morphological characters of this population are consistent with the description of P. coffeae (Castillo and Vovlas, 2007). Nematode DNA was extracted from an individual female. The primers of D2A/D3B (5′-ACAAGTACCGTGAGGGAAAGTTG-3′/5′-TCGGAAGGAACCAGCTACTA-3′) (Subbotin et al. 2006) and 18S/26S (5'-TTGATTACGTCCCTGCCCTTT-3' / 5'-TTTCACTCGCCGTTACTAAGG-3') (Vrain et al. 1992) were used to amplify the D2/D3 expansion region of the 28S rRNA gene and the rDNA internal transcribed spacer (ITS) region, respectively. The PCR products were purified and transformed to E. coli strain DH5α, and then sequenced by Sangon Biotech Co. Ltd. (Shanghai, China). The obtained sequences of the D2/D3 region (793 bp) and the ITS region (1,242 bp) were submitted to GenBank, and the accession numbers for D2/D3 region were OK103614 and OK103619 which had 98.6% and 100% identity with the reported P. coffeae sequences (KC490925); the two obtained ITS sequences accession numbers OK103603 and OK103613) had more than 99% identity with published P. coffeae sequences from GenBank (e.g., LC030410, LC030395, MH134508 and LC030380). Hence, both morphological and molecular data demonstrated the presence of P. coffeae. To further confirm reproduction on corn, the obtained RLN population was used to inoculate corn plants in 2-liter pots containing 1.8-liter sterilized and mixed soil with 2 pastoral soil: 1 substrate in greenhouse at 27°C. About 15 days after sowing, each pot with one corn plant (cv. Heyu 187) with the same growth status was selected to inoculate P. coffeae. Five small holes near the roots were made using a glass rod. Approximately 1,000 mixed stage nematodes of P. coffeae were then pipetted into the holes of each plant. Eight replications were performed. Eight additional pots of uninoculated corn plants were used as control. After 2 months, corn roots were washed and brown lesions were observed on roots. The average number of RLN/pot was approximately 5,030 in soil and 2,870 in roots, and each pot had an average of 7.9 reproduction factors (final population/initial population), indicating that this nematode population infects and reproduces well on this corn cultivar. No nematodes and symptoms was detected in the control pot. The nematode of P. coffeae has only been reported on corn in Guangdong, Liaoning, Shangdong and Henan Provinces in China (Liu et al. 1996; Liu et al. 2001; Xia et al. 2021). To our knowledge, this is the first report of P. coffeae infecting corn in Xinjiang Uygur Autonomous Region of China. Since RLN can cause considerable damage to corn, one of the most important food crops produced in China, strategic measures should be taken to prevent the spread of P. coffeae to other regions.
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Chen, Dahu, Ryan Barrett, Benjamin Mimee, Tanya Arseneault, Louis-Pierre Comeau, Kamrun Nahar, Sebastian Ibarra Jimenez, and Bernie J. Zebarth. "Prevalence of Verticillium spp. and Pratylenchus spp. in Commercial Potato Fields in Atlantic Canada." American Journal of Potato Research, July 5, 2024. http://dx.doi.org/10.1007/s12230-024-09957-3.
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AbstractA survey of New Brunswick (NB) and Prince Edward Island (PEI) potato fields in crop rotation phase prior to potato production was conducted in fall (October and November) between 2017 and 2021. A total of 113 and 126 fields for NB and PEI, respectively, were surveyed with 20 to 35 fields each year tested in each province. Root lesion nematodes (RLN, Pratylenchus spp.) were detected in 99 and 98% of the fields for NB and PEI, respectively, and two root lesion nematode species, P. crenatus and P. penetrans, were identified in both provinces from 2017 to 2021. Based on 2019 and 2020 results, all surveyed fields in NB and PEI were detected with P. crenatus, while only 29 and 43% of the fields in NB and PEI were detected with P. penetrans, respectively. P. crenatus accounted for 96 and 89% of the populations for NB and PEI, respectively, while P. penetrans accounted for 4 and 11% in commercial fields, respectively. In a single in-depth sampled experimental field with a history of severe potato early dying complex in 2018 in NB, P. crenatus accounted for 88% and P. penetrans was 12%. Verticillium dahliae was detected in 94 and 92% of potato fields in NB and PEI, respectively. All isolates obtained from potato cv. “Russet Burbank” in a baiting trial were V. dahliae, belonging to two lineages. V. albo-atrum was detected in a few fields at very low level, except two fields in NB where V. albo-atrum was predominating over V. dahliae. Rotation crops did not affect V. dahliae population densities for NB and PEI, and did not affect RLN population in NB, but significantly affected RLN in PEI. Fall green cover crop did not affect the populations of RLN and V. dahliae in PEI. The present study revealed that the potato pathogenic root lesion nematode P. penetrans was present in less than 50% of surveyed fields and accounted for around 10% of root lesion nematode population in NB and PEI, and V. dahliae was the dominant species and was present in greater than 90% of surveyed fields in both provinces.
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Mustafa, İmren, Göksel Özer, Timothy Paulitz, Alexei Morgounov, and Abdelfattah A. Dababat. "Plant-parasitic nematode associated with wheat in central, eastern, and south-eastern Kazakhstan." Plant Disease, March 23, 2021. http://dx.doi.org/10.1094/pdis-11-20-2424-sr.
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Kazakhstan is one of the biggest wheat producers, however, its wheat production is far below the average international wheat production standard due to biotic and abiotic stressors. Plant-parasitic nematodes are devastating for cereal production systems worldwide. A comprehensive survey was conducted in 2019 to identify plant-parasitic nematodes associated with wheat in different locations of central, eastern, and south-eastern Kazakhstan. The results revealed 33 root-lesion and 27 cyst nematode populations from the 77 localities sampled. These two genera occurred in separate or in mixed populations. The root-lesion populations were identified as Pratylenchus neglectus and P. thornei while all cyst nematodes were identified as Heterodera filipjevi. The identification of nematodes was firstly performed based on morphological and morphometric features and confirmed by BLAST and phylogenetic analyses based on the internal transcribed spacer and the D2-D3 expansion located in the 28S gene of ribosomal DNA for CCN and RLN populations, respectively. Pratylenchus neglectus and P. thornei populations from Kazakhstan showed a high similarity with the American, European, and Asian populations. Heterodera filipjevi populations formed a well-supported cluster with the corresponding populations from different countries and showed a slightly intraspecific polymorphism. Kazakhstan populations of H. filipjevi may have multiple introductions in Kazakhstan due to the divergence among them. The results of this study are of great importance for breeding programs and will enable awareness to extension advisors to develop measures to control these nematodes in cereal cropping areas in Kazakhstan.
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Orlando, Valeria, David Roberts, Simon G. Edwards, Thomas Prior, Roy Neilson, and Matthew A. Back. "Development and validation of four TaqMan real-time PCR diagnostics for the identification and quantification of Pratylenchus crenatus, Pratylenchus neglectus, Pratylenchus penetrans and Pratylenchus thornei." Nematology, February 29, 2024, 1–13. http://dx.doi.org/10.1163/15685411-bja10315.
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Summary Pratylenchus crenatus, P. neglectus, P. penetrans and P. thornei are globally the most commonly occurring species of root-lesion nematodes (RLN). Correct identification and quantification of these nematodes is important for strategic management interventions such as rotation choice and nematicide use. A real-time quantitative PCR can provide a fast and reliable alternative to morphological identification, which requires significant taxonomic experience. A TaqMan hydrolysis probe method based on the 28S rDNA D2-D3 expansion region was developed and validated for the identification and quantification of these four root-lesion nematode species. Standard curves for each target RLN species were generated by plotting known gene copy number, obtained by a ten-fold serial dilution of purified plasmids, with corresponding Ct values. Each standard curve had a strong linear correlation () between Ct value and gene copy number. There was consistent amplification of samples with target species from different geographic locations within the UK, whereas a lack of amplification was noted for selected non-target species: P. coffeae, P. pseudocoffeae, P. vulnus, P. fallax, Globodera rostochiensis, Meloidogyne hapla, Trichodorus primitivus and Bitylenchus hispaniensis. Specificity and sensitivity of the methods were confirmed by three experiments that explored different life stages, increasing the number of target species, and had mixed Pratylenchus samples. Finally, estimates obtained by qPCR methods were compared with counting carried out by microscopy showing a good correlation (). The TaqMan real-time PCR developed in this study provides a specific, fast and accurate quantification of P. crenatus, P. neglectus, P. penetrans and P. thornei.
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Gilarte, P., J. M. Plett, E. Pendall, Y. Carrillo, and U. N. Nielsen. "Soil nematodes modify interactions between nitrogen-fixing and non-fixing tree seedlings from late, but not early, successional stages." Plant and Soil, August 30, 2024. http://dx.doi.org/10.1007/s11104-024-06906-1.
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Abstract Aims Plant community dynamics are influenced by interspecific interactions. Previous studies have shown that soil organisms play a key role in such interactions, but few studies have quantified soil fauna contributions. Methods We investigated the effects of root lesion (RLN) and bacterial feeding (BFN) nematodes on the interaction between seedlings of nitrogen-(N)-fixing tree species of Acacia and non-fixing Banksia from early and late successional stages of a temperate forest in a pot experiment. Results Nematodes had consistent, albeit minor, negative effects on both N-fixers and non-fixers in the early successional stage scenario. By contrast, BFNs increased biomass production of both species in late-stage monocultures and in Banksia in mixed cultures. Moreover, RLNs negatively affected late-stage Banksia in monocultures but promoted its biomass production when grown with Acacia. Reduced 15N concentration in Banksia indicates that the switch was driven by transfer of N from Acacia facilitated by RLN. Conclusions Soil nematodes thus moderate interspecific interactions differently in early and late successional stages.
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Kumar, Ashish, Yogesh Dashrath Naik, Vedant Gautam, Sunanda Patil, Vinod Valluri, Sonal Channale, Jayant Bhatt, et al. "Genome‐wide association mapping reveals novel genes and genomic regions controlling root‐lesion nematode resistance in chickpea mini core collection." Plant Genome, September 13, 2024. http://dx.doi.org/10.1002/tpg2.20508.
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AbstractRoot‐lesion nematodes (RLN) pose a significant threat to chickpea (Cicer arietinum L.) by damaging the root system and causing up to 25% economic losses due to reduced yield. Worldwide commercially grown chickpea varieties lack significant genetic resistance to RLN, necessitating the identification of genetic variants contributing to natural resistance. This study identifies genomic loci responsible for resistance to the RLN, Pratylenchus thornei Sher & Allen, in chickpea by utilizing high‐quality single nucleotide polymorphisms from whole‐genome sequencing data of 202 chickpea accessions. Phenotypic evaluations of the genetically diverse set of chickpea accessions in India and Australia revealed a wide range of responses from resistant to susceptible. Genome‐wide association studies (GWAS) employing Fixed and Random Model Circulating Probability Unification (FarmCPU) and Bayesian‐Information and Linkage‐Disequilibrium Iteratively Nested Keyway (BLINK) models identified 44 marker‐trait associations distributed across all chromosomes except Ca1. Crucially, genomic regions on Ca2 and Ca5 consistently display significant associations across locations. Of 25 candidate genes identified, five genes were putatively involved in RLN resistance response (glucose‐6‐phosphate dehydrogenase, heat shock proteins, MYB‐like DNA‐binding protein, zinc finger FYVE protein and pathogenesis‐related thaumatin‐like protein). One notably identified gene (Ca_10016) presents four haplotypes, where haplotypes 1–3 confer moderate susceptibility, and haplotype 4 contributes to high susceptibility to RLN. This information provides potential targets for marker development to enhance breeding for RLN resistance in chickpea. Additionally, five potential resistant genotypes (ICC3512, ICC8855, ICC5337, ICC8950, and ICC6537) to P. thornei were identified based on their performance at a specific location. The study's significance lies in its comprehensive approach, integrating multiple‐location phenotypic evaluations, advanced GWAS models, and functional genomics to unravel the genetic basis of P. thornei resistance. The identified genomic regions, candidate genes, and haplotypes offer valuable insights for breeding strategies, paving the way for developing chickpea varieties resilient to P. thornei attack.
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Hu, Yaojun, Ling Qin, Wenlong Niu, Hang Ren, Ke Wang, Hong-Lian Li, Yan Shi, Hongxia Yuan, and Yu Li. "Pratylenchus zeae a causative agent of Corn Root Rot in Jiangsu Province of China." Plant Disease, February 23, 2023. http://dx.doi.org/10.1094/pdis-10-22-2456-pdn.
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Corn (Zea mays L.) plays an important role in China's cash crops, not only as food, but a vital raw material for animal husbandry and industry (Li et al. 2022). Pratylenchus zeae is one of the most damaging root-lesion nematodes (RLN) that can result in decreased yield and quality of crops (Liu et al. 2017). In September 2020, five root/soil samples were collected from the rhizosphere of corn (cv. Zhengdan 958), which had weak growth and root brown lesions in Chenzhou Village, Taolin Town, Donghai County, Lianyungang City, Jiangsu Province of China. Nematodes were extracted from the collected samples using the modified Baermann funnel method (Hooper et al. 2005). RLN were found in all samples, an average of 46 RLN per gram of root and 138 RLN per 100 cm3 of soil. The obtained RLN females were sterilized with 0.3% streptomycin sulfate and then inoculated on each carrot disks individually to obtain the purified population. RLN were examined by morphological and molecular characteristics to confirm the species indentification. The main morphological measurements of adult (n = 15) included body length = 524.7 μm (mean) ± 15.1 (standard deviation) (range = 490.7 to 543.6 μm), stylet = 15.2 μm ± 0.8 (14.2 to 16.8 μm), tail length = 30.3 μm ± 2.5 (26.3 to 35.3 μm), a = 25.6 ± 1.3 (24.4 to 29.3), b = 5.3 ± 0.3 (4.7 to 5.8), c = 17.4 ± 1.4 (14.9 to 19.3), two annules on the lip region. No males were found in the specimens. The morphological characters of this population are consistent with the description of P. zeae (Castillo and Vovlas, 2007). Furthermore, DNA was extracted from individual nematodes. The primers of TW81/AB28 and D2A/D3B (Subbotin et al. 2006) were used to amplified the rDNA-ITS region and rDNA 28S D2-D3 region, respectively. The purified PCR products were ligated into One step ZTOPO-Blunt/TA vector and transformed to Escherichia coli strain DH5α, and then sequenced by Sunya Biotechnology Co., Ltd (Henan, China). The obtained seqences were submitted to NCBI. The rDNA-ITS sequences (669 bp, GenBank Accession No: OP456372 and OP466367) exhibited 95.0% to 97.1% of identity with P. zeae sequences (KU198980 and KU198975). The obtained D2-D3 region of the 28S rDNA sequences (782 bp, OP441397 and OP448675) exhibited 99.7% to 100% identity with P. zeae sequences (EU130893 and KY424269). Consequently, both morphological and molecular data confirmed the identity of P. zeae. To further confirm reproduction on corn, single corn seeds (cv. Zhengdan 958) were sown in eight 2-liter pots filled with 1.8-liter of sterilized soil in greenhouse at 28°C. About 15 days after sowing, each pot with one corn plant with the same growth status was selected to inoculate with 1,000 mixed stage nematodes of P. zeae , Eight pots of uninoculated corn plants were used as controls. After 60 days, the inoculated plants were harvested and brown lesions were observed on roots. No symptoms and nematodes was detected in the control. An average number of RLN per pot was 3,752 in soil and 1,183 in roots were extracted, the reproduction factor (final population/initial population) was 4.94, indicating that P. zeae infects and reproduces well on this corn cultivar. P. zeae has only been reported on corn in Guangxi Province, southern in China(Fang et al. 1994). To our knowledge, this is the fist report of P. zeae infecting corn in Jiangsu Province, eastern in China. As P. zeae can cause great damage to corn, necessary measures should be taken to prevent the spread of P. zeae to other areas.
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Qiao, Wanqiang, Yonggang Liu, Min Zhang, Mingming Shi, Jin Wu, and Huixia Li. "First Report of the Root-Lesion Nematode (Pratylenchus thornei Sher and Allen, 1953) Parasitizing Oats in Gansu Province, China." Plant Disease, March 14, 2023. http://dx.doi.org/10.1094/pdis-05-22-1131-pdn.
Full textAbstract:
Oat (Avena sativa L.) is a vital cereal crop and serves as food, feed, and industrial material for many commercial growers. The presence of root-lesion nematodes (RLN; Pratylenchus spp.) in oat-cultivated areas of China is alarming because RLNs display an endo-migratory life cycle and rank third among the most damaging nematode pests (Jones et al. 2013). Their penetration and feeding cause necrotic lesions on the roots, which further dispose plants to other soilborne pathogens resulting in extensive root rots (LaMondia, 2003). In China, it has been reported that P. thornei harmed sugarcane and wheat. (Fang et al 1994; Fan et al. 2020), However, there are no reports on the damage of P. thornei to oat. In June 2021, a survey of one oat field, exhibiting poorly developed plants reduced till number and distinct lesions on roots was conducted in Dingxi city, Gansu province, China (N 35°56′, E 104°60′). Thirteen soil and root samples were collected from symptomatic plants (cultivar: Jizhangyan No.5). Nematodes were extracted from root and soil samples using the modified Baermann funnel method (Hooper, 1986). Twelve samples tested positive for the presence of RLN with population densities ranging from 3 to 25 juveniles and females/100 g of soil and 2 to 32/g of root. No males were detected. Twenty females from the twelve positive samples were selected at random and examined morphologically for species-level identification (Figure 1A-J). The female bodies were slender, almost straight or ventrally curved after heat relaxation (Figure 1A), labial region continuous with the rest of the body and bears three faint lip annuli. The stylets were short and stout with well-developed basal knobs (Figure 1C, G). The pharyngeal and reproductive components were typical of pratylenchid nematodes (Figure 1B). Tail region cylindrical, straight or curved ventrally, having variable terminus viz., broad, bluntly rounded or truncate, with no striations around terminus (Figure 1H-J). The diagnostic morphometrics of adult females were as follows: body length 591.4 ± 20.1 μm (466.6 to 742.7 μm), body width 22.5 ± 0.5 μm (20.1 to 26.2 μm), distance from anterior end to excretory pore 88.4 ± 3.5 μm (75.7 to 99.7 μm), stylet length 16.8 ± 0.2 μm (15.2 to 18.7 μm), and tail length 33.7 ± 1.3 μm (25.5 to 43.2 μm). De man’s morphometric parameters were a: 26.3 ± 0.8 (19.8 to 31.1), b: 5.7 ± 0.2 (4.7 to 7.0), c: 17.9 ± 0.8 (12.9 to 23.7), c’: 2.3 ± 0.1 (1.7 to 2.8) and V value was 77.8 % ± 1.2 (67.3 to 86.6 %). The morphological and morphometric characteristics of our detected population is consistent with Loof’s 1960 description of P. thornei Sher and Allen, 1953 (Table 1). For molecular analysis, five females from the twelve positive samples were selected at random for molecular analysis. DNA was extracted from single females according to the method of Wang et al. (2011). The ITS region was amplified by primer pair 18S/26S (Vrain et al., 1992) and the D2/D3 expansion region of the 28S rDNA was amplified by primer pair D2A/D3B (Castillo et al., 2003). High quality PCR products of accurate fragment length were sent to the Tsingke Biological Technology (Xian, China) for sequencing. The ITS sequences (813 bp-817 bp, GenBank OP902282, OP902284, OP902287, OP902288 and OP902289) of Gansu population showed 99.26%-100% sequence identity with P. thornei reported from Italy (FR692299, FR692303 and FR692304) (Figure 2). The 28S sequences (738 bp-764 bp, GenBank OM278343, OP217988, OP218403, OP218404 and OP218567) showed 100% identity with P. thornei populations reported from Belgium (KY828302), the USA (OK490327) and Iran (JX261960) (Figure 3). Morphological and molecular data of the Gansu population obtained in this study supported its identification as P. thornei. The endo-migratory association of the host-nematode relationship was confirmed by observing nematodes inside the roots using acid fuchsin root staining (Wu et al. 2014) (Figure 4). Oat (cultivar: Jizhangyan No.5) seeds were sown in pots containing 500 g of naturally infested soil (an average of 12 P. thornei /100g of soil); autoclaved soil was used as a control. Fifty seeds were directly sown in pots (20 × 16 cm), with three replicates. Plants were maintained in an incubator at 28 ± 1°C (12 h/12 h light/dark). Results indicated that plants inoculated obviously grew poorly with some lesions on roots and P. thornei numbers in them increased 16 times both in soil (50.7 ± 9.6 nematodes/100g) and roots (708.0 ± 8.7 nematodes in the entire root system). No P. thornei was found in the control soil and roots (Figure 5). Morphological and molecular characteristics of specimens isolated from oat symptomatic roots (n = 10) were identical to P. thornei. The losses caused by P. thornei are still unknown, and considering Pratylenchus spp. are commercially important nematode, the more investigations on oats should be made in the future. As of yet, RLNs were not reported from any oat-cultivated areas of China. To our knowledge, this is the first report of P. thornei parasitizing oats in the Gansu province of China.
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Singh, Gurminder, Ashmit KC, Karansher Singh Sandhu, Andrew J. Friskop, Zhaohui Liu, and Guiping Yan. "Evaluation of Wheat Cultivars and Germplasm Lines for Resistance to Pratylenchus neglectus Populations Collected in North Dakota." Plant Disease, May 25, 2023. http://dx.doi.org/10.1094/pdis-03-23-0590-re.
Full textAbstract:
Root-lesion nematode (RLN; Pratylenchus neglectus) is a migratory endoparasite and a major soil-borne pathogen that affects wheat (Triticum spp.) production worldwide. Genetic resistance is one of the most economical and effective ways to manage P. neglectus in wheat. This study evaluated 37 local cultivars and germplasm lines in seven greenhouse experiments, including 26 hexaploid wheat, six durum wheat, two synthetic hexaploid wheat, one emmer wheat, and two triticale for P. neglectus resistance from 2016 to 2020. North Dakota field soils infested with two RLN populations (350 to 1,125 nematodes per kilogram of soil) were used for resistance screening under controlled greenhouse conditions. The final nematode population density for each cultivar and line was counted under the microscope to categorize the resistance ranking of these entries as resistant, moderately resistant, moderately susceptible, and susceptible. Out of the 37 cultivars and lines, one was classified as resistant (Brennan), 18 were moderately resistant (Divide, Carpio, Prosper, Advance, Alkabo, SY Soren, Barlow, Bolles, Select, Faller, Briggs, WB Mayville, SY Ingmar, W7984, PI 626573, Ben, Grandin, and Villax St. Jose), 11 were moderately susceptible, and seven were susceptible to P. neglectus. The resistant to moderate resistant lines identified in this study could be used in breeding programs after the resistance genes or loci are further elucidated. This research provides valuable information about P. neglectus resistance among wheat and triticale cultivars used in the Upper Midwest region of the USA.
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Chen, Dahu, Judith Nyiraneza, Kamrun Nahar, Danielle Murnaghan, Jessica Matheson, Ryan Barrett, Kyra Stiles, Tandra D. Fraser, and Rick D. Peters. "Impacts of Primary Non-Inversion Shallow Tillage and Moldboard Plowing on the Potato Early Dying Disease Complex in Prince Edward Island, Canada." American Journal of Potato Research, March 25, 2025. https://doi.org/10.1007/s12230-025-09987-5.
Full textAbstract:
Abstract Conservation tillage has shown potential to improve soil health and enhance crop productivity in various cropping systems. Moldboard plowing (MP) in the fall prior to the potato phase is a conventional practice in Prince Edward Island (PEI), Canada, which leaves the soil prone to erosion and soil organic matter decline. Potato early dying disease complex (PED) is a major yield limiting factor in potato production in PEI. The objective of this four-year (2019–2022) study conducted in 14 commercial fields was to determine the effect of non-inversion shallow tillage (ST) in comparison with MP on PED pathogen population density in the spring at potato planting time and in the fall post-potato harvesting, and on PED disease severity. Root lesion nematodes (Pratylenchus spp., RLN) were detected in all fields. Verticillium dahliae was the predominant species in all fields, while V. albo-atrum was sporadically detected in a few samples. The population density of the RLN and V. dahliae varied among the fields. In the spring samples, V. dahliae density was significantly higher in 5 of the 14 fields with the ST treatment compared with MP. RLN density was significantly higher in one of the 14 fields with the ST. When averaged across all fields, V. dahliae density was 1.8-fold higher with ST than with MP (p = 0.018), but no differences were detected for RLN density between ST and MP. In the fall after the potato harvest, only two fields had significantly higher V. dahliae density with the ST than with MP, and no differences were detected for RLN density between ST and MP. When combined data across all fields were analyzed, no differences in pathogen population levels were detected between ST and MP for both V. dahliae and RLN. Higher PED severity was detected in three fields associated with ST. However, when disease ratings were averaged across all fields, no PED severity difference was detected between ST and MP. The PED severity was significantly positively related to the spring population density of V. dahliae and RLN, but not with the tillage regimes in this study. Further study is needed to determine the long-term effect of tillage regimes on soil health, disease development, soil disease suppressiveness, pathogen population dynamics and PED development in potato production.
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Gao, Lingling, Yunlong Lv, Can Zhang, Wen-Long Niu, Hong-Lian Li, Yu Li, and Ke Wang. "Discovery of Pratylenchus zeae Causing Root Rot of Winter Wheat in Anhui Province of China." Plant Disease, April 4, 2025. https://doi.org/10.1094/pdis-02-25-0327-pdn.
Full textAbstract:
Root-lesion nematode (RLN), Pratylenchus zeae Graham, 1951, is a serious nematode pest in a number of agronomic and industrial crops (Liu et al. 2017). Wheat (Triticum aestivum) is one of the most important food crops in Anhui province of China. In May 2023, a survey was conducted for RLNs in winter wheat fields in Woyang county of Bozhou City, Anhui province, China. The samples were collected about 20 days before wheat (cv. Gushenmai 19) harvest. The plants were growing poorly, with distinct brown lesions on the wheat roots. The RLNs were extracted with the modified Baermann funnel apparatus (Hooper et al. 2005). The RLNs were found in eight collected samples, an average of 51 nematodes per gram of root and 128 nematodes per 100 cm3 of soil. The extracted RLNs were disinfected with 0.3% streptomycin sulfate and one individual female nematode were cultured on carrot disks at 25°C for propagation as described before (Wang et al. 2021). The RLNs species identification was based on morphological and molecular criteria. The main morphological measurements of adult females (n = 15) included body length = 490.5 μm (mean) ± 13.1 (standard deviation) (range = 471.3 to 523.1 μm), stylet length = 16.1 μm ± 0.7 (14.0 to 16.9 μm), tail length = 27.3 μm ± 5.3 (18.9 to 34.1 μm), a = 24.8 ± 1.8 (21.9 to 27.8), b = 5.2 ± 0.3 (4.5 to 5.9), c = 17.8 ± 1.9 (14.9 to 20.3), two annules on the lip region. No males were found in the specimens. The morphological characters of this population are consistent with P. zeae as described previously (Castillo and Vovlas, 2007). Furthermore, the individual female was used for the molecular identification, and the DNA was extracted as described previously (Wang et al. 2011). The primers of D2A/D3B (Subbotin et al. 2006) and TW81/AB28 (Vovlas et al. 2011) were used to amplify the rDNA 28S D2-D3 region and rDNA-ITS region, respectively. The PCR products were sequenced, the newly obtained sequences of the rDNA 28S D2-D3 region (782 bp) and rDNA-ITS region (669 bp) in this study were submitted to NCBI. The obtained 28S D2-D3 region sequence (GenBank Accession No. PQ859281 and PV083139) had 100% identity with P. zeae sequences available from GenBank (KY424256 and KY424263). The obtained ITS sequences in this study (PQ857687 and PV089700) had more than 98% identity with P. zeae sequences available from GenBank (OP456372 and OP466367). Both morphological and molecular data confirmed the presence of P. zeae. To validate the reproductive capacity of the RLNs on winter wheat, a greenhouse experiment was conducted at 25°C, following the modified Koch's postulates protocol. Wheat plants were grown in 8 pots, each with three plants (cv. Gushenmai 19) were inoculated with 1000 P. zeae and grown in 1.5-liter pots. Two months after inoculation, the wheat roots were washed and brown lesions were observed. RLNs in the soil and roots were extracted as previously described and the population was found to have increased substantially. The average of final number of nematodes/pot was about 1859 in soil and 793 in roots. The reproduction factors (final population/initial population) were greater than 1 (mean 2.65). Those results confirmed that this nematode population infects and reproduces well on this wheat cultivar. P. zeae has only been reported on winter wheat in Shanxi Province of China (Liu et al. 2007). To our knowledge, this is the first report of P. zeae infecting winter wheat in Anhui province of China. Since P. zeae can cause considerable damage to winter wheat, strategic measures should be taken to prevent the spread of P. zeae to other regions.
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Kessler, Alexandra, and Alyssa Koehler. "A survey of plant parasitic nematodes of soybeans in Delaware and Maryland 2019-2021." Plant Health Progress, October 9, 2022. http://dx.doi.org/10.1094/php-07-22-0064-s.
Full textAbstract:
Soybean cyst nematode is the most yield-limiting pathogen of soybean across Delaware (DE) and eastern shore Maryland (MD). To update nematode distribution and population data, a three-year soil survey was conducted from 2019 to 2021. Soybean fields across DE and nine MD counties were sampled from August through October. Three hundred and eleven soil samples were collected, including two hundred and 22 predictive samples and 89 diagnostic samples. Across all samples, nine nematode taxa were identified. Soybean cyst nematode (Heterodera glycines, 53.38%), root-knot nematode (Meloidogyne incognita, 18.33%), lesion nematode (Pratylenchus spp., 57.23%), and spiral nematode (Helicotylenchus spp., 54.34%) were most abundant in the region. Among these taxa, 66% of SCN samples had populations above the economic threshold; 39% of RKN; and 14% of lesion. Results from this survey highlight the continued challenge of SCN in the region and that other nematode taxa like RKN and lesion should be monitored. Many fields have multiple nematode genera present, and interactions are poorly understood.
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Kumar, Deepak, Shiveta Sharma, Rajiv Sharma, Saksham Pundir, Vikas Kumar Singh, Deepti Chaturvedi, Bansa Singh, Sundeep Kumar, and Shailendra Sharma. "Genome-wide association study in hexaploid wheat identifies novel genomic regions associated with resistance to root lesion nematode (Pratylenchus thornei)." Scientific Reports 11, no. 1 (February 11, 2021). http://dx.doi.org/10.1038/s41598-021-80996-0.
Full textAbstract:
AbstractRoot lesion nematode (RLN; Pratylenchus thornei) causes extensive yield losses in wheat worldwide and thus pose serious threat to global food security. Reliance on fumigants (such as methyl bromide) and nematicides for crop protection has been discouraged due to environmental concerns. Hence, alternative environment friendly control measures like finding and deployment of resistance genes against Pratylenchus thornei are of significant importance. In the present study, genome-wide association study (GWAS) was performed using single-locus and multi-locus methods. In total, 143 wheat genotypes collected from pan-Indian wheat cultivation states were used for nematode screening. Genotypic data consisted of > 7K SNPs with known genetic positions on the high-density consensus map was used for association analysis. Principal component analysis indicated the existence of sub-populations with no major structuring of populations due to the origin. Altogether, 25 significant marker trait associations were detected with − log10 (p value) > 4.0. Three large linkage disequilibrium blocks and the corresponding haplotypes were found to be associated with significant SNPs. In total, 37 candidate genes with nine genes having a putative role in disease resistance (F-box-like domain superfamily, Leucine-rich repeat, cysteine-containing subtype, Cytochrome P450 superfamily, Zinc finger C2H2-type, RING/FYVE/PHD-type, etc.) were identified. Genomic selection was conducted to investigate how well one could predict the phenotype of the nematode count without performing the screening experiments. Prediction value of r = 0.40 to 0.44 was observed when 56 to 70% of the population was used as a training set. This is the first report where GWAS has been conducted to find resistance against root lesion nematode (P. thornei) in Indian wheat germplasm.
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Chen, Dahu, Bernie J. Zebarth, Claudia Goyer, Louis-Pierre Comeau, Kamrun Nahar, and Tom Dixon. "Effect of Biofumigation on Population Densities of Pratylenchus spp. and Verticillium spp. and Potato Yield in Eastern Canada." American Journal of Potato Research, April 13, 2022. http://dx.doi.org/10.1007/s12230-022-09875-2.
Full textAbstract:
AbstractBiofumigation has been proposed as an alternative to soil fumigation to manage soil-borne diseases including potato early dying disease complex (PED). This study examined the potential of using brown mustard (Mustard juncea) biofumigation to manage PED under rain-fed potato production in New Brunswick, Canada in two trials between 2017 and 2020 in comparison with chloropicrin fumigation and a conventional barley rotation. Biofumigation increased yield in one trial, but not in a second trial where the potato crop experienced severe drought, whereas chloropicrin fumigation increased yield in both trials. Biofumigation was effective in suppressing root-lesion nematode (RLN, Pratylenchus spp.) counts in both trials, but was ineffective in suppressing V. dahliae population density. Chloropicrin fumigation was effective in suppressing RLN counts and V. dahliae population density only in the hill where injected, but the effect was short-lived as the population density of V. dahliae in the hill increased to the level of the control in one potato growing season. Biofumigation may be an alternative to chloropicrin fumigation in managing PED, particularly in fields with high RLN population but relatively low Verticillium population density. However, neither biofumigation nor fumigation used alone may be sustainable in the short-term potato rotations commonly used in New Brunswick, and additional beneficial practices are required to sustain productivity in the long-term.