Academic literature on the topic 'Root exudates'
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Journal articles on the topic "Root exudates"
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Lei, Xue, Yuting Shen, Jianing Zhao, Jiajia Huang, Hui Wang, Yang Yu, and Chunwang Xiao. "Root Exudates Mediate the Processes of Soil Organic Carbon Input and Efflux." Plants 12, no. 3 (January 31, 2023): 630. http://dx.doi.org/10.3390/plants12030630.
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Root exudates, as an important form of material input from plants to the soil, regulate the carbon input and efflux of plant rhizosphere soil and play an important role in maintaining the carbon and nutrient balance of the whole ecosystem. Root exudates are notoriously difficult to collect due to their underlying characteristics (e.g., low concentration and fast turnover rate) and the associated methodological challenges of accurately measuring root exudates in native soils. As a result, up until now, it has been difficult to accurately quantify the soil organic carbon input from root exudates to the soil in most studies. In recent years, the contribution and ecological effects of root exudates to soil organic carbon input and efflux have been paid more and more attention. However, the ecological mechanism of soil organic carbon input and efflux mediated by root exudates are rarely analyzed comprehensively. In this review, the main processes and influencing factors of soil organic carbon input and efflux mediated by root exudates are demonstrated. Soil minerals and soil microbes play key roles in the processes. The carbon allocation from plants to soil is influenced by the relationship between root exudates and root functional traits. Compared with the quantity of root exudates, the response of root exudate quality to environmental changes affects soil carbon function more. In the future, the contribution of root exudates in different plants to soil carbon turnover and their relationship with soil nutrient availability will be accurately quantified, which will be helpful to understand the mechanism of soil organic carbon sequestration.
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Qu, Peng, Butian Wang, Meijun Qi, Rong Lin, Hongmei Chen, Chun Xie, Zhenwei Zhang, Junchao Qiu, Huabo Du, and Yu Ge. "Medicinal Plant Root Exudate Metabolites Shape the Rhizosphere Microbiota." International Journal of Molecular Sciences 25, no. 14 (July 16, 2024): 7786. http://dx.doi.org/10.3390/ijms25147786.
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The interactions between plants and rhizosphere microbes mediated by plant root exudates are increasingly being investigated. The root-derived metabolites of medicinal plants are relatively diverse and have unique characteristics. However, whether medicinal plants influence their rhizosphere microbial community remains unknown. How medicinal plant species drive rhizosphere microbial community changes should be clarified. In this study involving high-throughput sequencing of rhizosphere microbes and an analysis of root exudates using a gas chromatograph coupled with a time-of-flight mass spectrometer, we revealed that the root exudate metabolites and microorganisms differed among the rhizosphere soils of five medicinal plants. Moreover, the results of a correlation analysis indicated that bacterial and fungal profiles in the rhizosphere soils of the five medicinal plants were extremely significantly or significantly affected by 10 root-associated metabolites. Furthermore, among the 10 root exudate metabolites, two (carvone and zymosterol) had opposite effects on rhizosphere bacteria and fungi. Our study findings suggest that plant-derived exudates modulate changes to rhizosphere microbial communities.
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Hussien, Ahmad M., and Muntaha Sabaa Abbas. "Effect of Allelopathic Potential of some Plants Root Exudates Concerning Growth and Pathogenicity of some Fungus on Brassica oleracea Varplant." IOP Conference Series: Earth and Environmental Science 1158, no. 7 (April 1, 2023): 072006. http://dx.doi.org/10.1088/1755-1315/1158/7/072006.
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Abstract The study aims to evaluate the effectiveness of allelopathic exudates of five plant species, namely (maize, barley, Sunflower, chard, and mung bean) concerning the release of organic substances exudated from their roots and their effect on the germination and growth of brassica oleracea var plant, as well as their impact on the growth of two isolated fungi, Rhizoctona solani and Pythium ulitmum. According to the laboratory results, chard root exudates had the highest rate of Brassica oleracea var seed germination, reaching 100%, while maize plant exudates had the lowest rate, 23.33%, compared to the control treatment, which was 100%. Sunflower and mung bean plant exudates had germination rates of 50, 43%, respectively, while barley exudates had a germination rate of 90%. Furthermore, the laboratory results also revealed discrepancy in the above-mentioned root exudates regarding the reduction of the diagonal growth of the two fungi, R.solani and P. ulitmum. Obviously, 10-day-old chard root exudates outperformed in reducing the diagonal growth of both fungi, with an average colony diameter of 0.00 cm for P. ulitmum and 1.59 cm for R.solani when compared by the control treatment (water only), which amounted to 9.00 cm. On other hand, Sunflower root exudates had the highest diagonal growth of the two fungi was reaching to 4.86 cm for R.solani and 8.50 cm for P. ulitmum. The chemical analysis of these five plants’ exudates shows that the highest concentration of the terpene compound was obtained by separating this compound from chard root exudates, using HPLC method, which amounted 3.55 55 μg/g. While the least concentration was in the maize treatment, which reached 15 μg/g. Whereas the total phenolic compounds were more concentrated in the root exudates of mung bean, which reached 52.69 μg/g, and the lowest concentration was in the root exudates of Sunflower reaching 7.89 μg/g. With regard to, the ferulic acid compound, the highest rate was observed in the root exudates of mung bean, which amounted to 19.87 μg/g, then, chard control comes in second place in which the concentration reached 10.25 μg/g. while the least concentration of the same compound was in Sunflower root exudates reached 5.69 μg/g. Seemingly, the diversity and variation of concentrations of allopathic compounds exudated from the roots of these plants, which may either negatively or positively affect the germination of Brassica oleracea var plant and the accompanying pathogenic fungi, are considered to be the cause of the varying effect of the understudied plant roots’ metabolites on germination percentages of Brassica oleracea var plant as well as in the reduction of the diagonal growth of the both fungi, R. solani and P. ulitmum.
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Zhang, Cheng-Sheng, Yanfen Zheng, Lijuan Peng, and Jianmin Cao. "Rootstock-Scion Interaction Affects the Composition and Pathogen Inhibitory Activity of Tobacco (Nicotiana tabacum L.) Root Exudates." Plants 9, no. 12 (November 26, 2020): 1652. http://dx.doi.org/10.3390/plants9121652.
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The composition and allelopathy to Phytophthora nicotianae (the causal agent of tobacco black shank disease) of root exudates from a resistant tobacco (Nicotiana tabacum L.) cultivar Gexin 3, a susceptible cultivar Xiaohuangjin 1025 and their reciprocal grafts were investigated. Grafting with disease-resistant rootstock could improve resistance to black shank; this is closely related to the allelopathy of root exudates. The root exudates from the resistant cultivar inhibited the growth of P. nicotianae, while those from the susceptible cultivar promoted the growth; the grafting varieties had intermediate properties. The root exudate composition differed among cultivars. Gexin 3 was rich in esters and fatty acids, while Xiaohuangjin 1025 contained more hydrocarbons and phenolic acids. The composition of root exudates of grafted cultivars as well as their allelopathy to P. nicotianae were altered, and tended to be close to the composition of cultivar used as rootstock. Eugenol, 4-tert-butylphenol, mono (2-ethylhexyl) phthalate, 4-hydroxybenzoic acid, 2,6-di-tert-butylphenol, dipropyl phthalate, and methyl myristate were identified as the main compounds contributing to inhibitory properties of root exudates. Sorbitol was suggested to play a role in disease induction. Overall, rootstock–scion interaction affected the composition of tobacco root exudates, which may be attributed to the different disease resistance among grafted plants, rootstock and scion.
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Suwandi, S., T. P. Rahmadhani, S. Suparman, C. Irsan, and A. Muslim. "Allelopathic potential of root exudates from perennial herbaceous plants against Ganoderma boninense." IOP Conference Series: Earth and Environmental Science 976, no. 1 (February 1, 2022): 012053. http://dx.doi.org/10.1088/1755-1315/976/1/012053.
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Abstract Allelopathic potential of root exudates from edible perennial herbaceous (Canna indica, Maranta arundinacea, and Xanthosoma sagittifolium) against mycelium of Ganoderma boninense, basal stem rot pathogen of oil palm has been studied in vitro. Root exudates were extracted from 10-day old aseptically growing plants generated from surface-sterilized corm or rhizome on water agar. Allelopathic activity was tested based on inhibition of G. boninense mycelial growth on malt extract agar supplemented with 0.1 and 1.0 μL mL−1 ethyl acetate extract of root exudates. Root exudate from X. sagittifolium and C. indica was found to significantly inhibit the mycelial growth of G. boninense at 0.1 and 1.0 μL mL−1, respectively.
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Zhang, Jiale, Qianwen Liu, Kun Li, and Li Ma. "Peanut Root Exudates Suppress Fusarium solani and Modulate the Microbial Community Structure of Rhizosphere in Grape Replant Soil." Horticulturae 8, no. 10 (September 29, 2022): 892. http://dx.doi.org/10.3390/horticulturae8100892.
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Replant disease significantly hinders the development of the grape industry, and the imbalance of the rhizosphere microecological environment is one of the fundamental reasons hindering grape replants. Peanut is a common intercropping crop, and whether the root exudates of peanut can alleviate grape replant obstacles is still unknown. In this study, the effects of exogenous peanut root exudates on replanting grapevine growth, and the microbial community structure of grapevine replant soils were studied. The results showed that peanut root exudates could promote the growth of replanting grapevine seedlings; enhance root vigor and SOD activity, increasing 55.18% and 95.71%, respectively; and reduce the MDA content of root, decreasing 31.10%. After peanut exudate treatment, the growth of Fusarium solanum, an important harmful fungus that is an obstacle to grape replant, was inhibited. The relative abundances of Gaiella in bacteria and Cystobasidium and Mortierella in fungi increased, and the potential pathogen fungi Fusicolla decreased. Peanut root exudates also modified the soil bacterial and fungal community in a certain range and increased the interaction among the bacteria of grapevine rhizosphere soil. However, they loosened the interaction among fungi. There are extensive mutualistic interactions among bacteria or fungi in grape rhizosphere assemblages after peanut exudates treatment. Therefore, peanut root exudates might be helpful in changing the soil microbial environment and alleviating the grape replanting obstacle.
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Burak, Emma, John N. Quinton, and Ian C. Dodd. "Root hairs are the most important root trait for rhizosheath formation of barley (Hordeum vulgare), maize (Zea mays) and Lotus japonicus (Gifu)." Annals of Botany 128, no. 1 (April 20, 2021): 45–57. http://dx.doi.org/10.1093/aob/mcab029.
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Abstract Background and Aims Rhizosheaths are defined as the soil adhering to the root system after it is extracted from the ground. Root hairs and mucilage (root exudates) are key root traits involved in rhizosheath formation, but to better understand the mechanisms involved their relative contributions should be distinguished. Methods The ability of three species [barley (Hordeum vulgare), maize (Zea mays) and Lotus japonicus (Gifu)] to form a rhizosheath in a sandy loam soil was compared with that of their root-hairless mutants [bald root barley (brb), maize root hairless 3 (rth3) and root hairless 1 (Ljrhl1)]. Root hair traits (length and density) of wild-type (WT) barley and maize were compared along with exudate adhesiveness of both barley and maize genotypes. Furthermore, root hair traits and exudate adhesiveness from different root types (axile versus lateral) were compared within the cereal species. Key Results Per unit root length, rhizosheath size diminished in the order of barley > L. japonicus > maize in WT plants. Root hairs significantly increased rhizosheath formation of all species (3.9-, 3.2- and 1.8-fold for barley, L. japonicus and maize, respectively) but there was no consistent genotypic effect on exudate adhesiveness in the cereals. While brb exudates were more and rth3 exudates were less adhesive than their respective WTs, maize rth3 bound more soil than barley brb. Although both maize genotypes produced significantly more adhesive exudate than the barley genotypes, root hair development of WT barley was more extensive than that of WT maize. Thus, the greater density of longer root hairs in WT barley bound more soil than WT maize. Root type did not seem to affect rhizosheath formation, unless these types differed in root length. Conclusions When root hairs were present, greater root hair development better facilitated rhizosheath formation than root exudate adhesiveness. However, when root hairs were absent root exudate adhesiveness was a more dominant trait.
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Mansour, Samira R., and John G. Torrey. "Frankia spores of strain HFPCgI4 as inoculum for seedlings of Casuarina glauca." Canadian Journal of Botany 69, no. 6 (June 1, 1991): 1251–56. http://dx.doi.org/10.1139/b91-162.
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Spore suspensions of Frankia strain HFPCgI4 originally isolated from root nodules of Casuarina glauca were studied with respect to their capacity to germinate in vitro in chemically defined media and added root exudates. Spore germination in general was low and prolonged but could be increased by chemical additions to the basal medium and increased further (doubled percentages) by adding suitable dilutions of root exudates from C. glauca seedlings. Spores inoculated directly on seedling roots at 108 spores/mL caused seedling root hair deformation in C. glauca and some root nodulation (35%). Spore inoculation under axenic conditions elicited limited root hair deformation and no nodulation. Evidence is provided showing that Frankia spores of isolate HFPCgI4 serve as effective agents in root hair infection when applied in nonsterile water culture conditions. Seedling root exudates may facilitate the infection process by stimulating Frankia spore germination. Key words: Frankia, nodulation, root hair infection, root exudate, spores.
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Baghestani, Ali, Claudel Lemieux, Gilles D. Leroux, Regis Baziramakenga, and Regis R. Simard. "Determination of allelochemicals in spring cereal cultivars of different competitiveness." Weed Science 47, no. 5 (October 1999): 498–504. http://dx.doi.org/10.1017/s0043174500092171.
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Competitive cereal cultivars are less susceptible than others to weed interference. Their characterization may provide selection criteria that can be used as guidelines to develop new, even more competitive cultivars. Root exudates are a potential means by which competitive cultivars reduce weed growth. The objectives of this study were to evaluate the effect of cereal root exudates onBrassica kaber(DC.) L. C. Wheeler growth, to isolate and characterize the allelochemical compounds released by spring cereal cultivars, and to determine if a relation exists between these allelochemicals and cultivar competitiveness. Highly competitive (HC) and lesser competitive (LC) cultivars of four crop kinds (Triticum aestivumL. [wheat],Avena sativaL. [wild oat], two- and six-rowedHordeum vulgareL. [barley]) were selected based on previous work. Exudates from undisturbed root systems ofB. kaberand cereals were collected and used in a bioassay test withB. kaber.Root exudates were analyzed for 16 common phenolic compounds using high-performance liquid chromatography (HPLC). Bioassays indicated that cereal exudates had no negative effect onB. kabergermination, but all concentrations of cereal root exudates inhibitedB. kaberroot and hypocotyl growth. As cereal root exudate concentration increased,B. kabergrowth decreased. For each crop kind,B. kabergrowth inhibition was greater with HC cultivars than with LC cultivars. The root exudates of all crop kinds and cultivars contained benzoic, caffeic, ferulic,o-coumaric, and vanillic acids as well as scopoletin. Para-hydroxybenzoic acid was found in exudates fromT. aestivum, A. sativa, and two-rowedH. vulgarecultivars. Para-coumaric acid was not identified in root exudates from LCH. vulgarecultivars. Gentisic acid was produced byA. sativaandH. vulgare.Vanillic ando-coumaric acids along with scopoletin may be responsible for the allelopathic effects ofH. vulgare, T. aestivum, andA. sativacultivars. These three compounds may be useful as possible indicators of allelopathic potential of genotypes under development and thus considered for use in breeding programs.
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Hiremath, Shivanand S., Narsing Laxmi Prasanna, Sudhakar S, Arvind M, Akshaya C.K., Rashmi Nigam, Sanjay Kumar, and Marimuthu Elangovan. "A Review on Role of Root Exudates in Shaping Plant-Microbe-Pathogen Interactions." Journal of Advances in Microbiology 24, no. 12 (November 23, 2024): 1–17. http://dx.doi.org/10.9734/jamb/2024/v24i12868.
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Root exudates are diverse compounds secreted by plant roots that significantly influence the rhizosphere-where complex interactions among plants, microbes, and pathogens occur. These exudates include sugars, amino acids, organic acids, phenolics, and volatile organic compounds, which collectively shape the microbial community structure in the soil. By attracting beneficial microbes like rhizobia, arbuscular mycorrhizal fungi (AMF), and plant growth-promoting rhizobacteria (PGPR), root exudates enhance nutrient acquisition, promote plant growth, and improve resistance to environmental stresses. Exudates can directly inhibit pathogens through the release of antimicrobial compounds such as benzoxazinoids and phenolics or indirectly by priming plant immune responses and inducing systemic resistance. Environmental factors like nutrient availability, soil pH, texture, and abiotic stressors (e.g., drought, salinity, and heavy metals) profoundly impact the composition and quantity of root exudates, thereby influencing their ecological functions. Phosphorus and iron deficiencies trigger the secretion of organic acids to mobilize these nutrients, while drought and salinity alter exudation patterns to recruit drought-tolerant microbes. Despite their potential, studying root exudates presents technical challenges, such as isolating exudates in natural soil systems and analyzing them with sufficient precision. Knowledge gaps also exist regarding the temporal dynamics of exudation and how these compounds influence multi-species plant-microbe interactions under field conditions. Future research should focus on breeding crops with optimized root exudate profiles for enhanced nutrient uptake, pathogen resistance, and resilience to climate change. Leveraging root exudates in developing biofertilizers, biostimulants, and integrated pest management (IPM) strategies can reduce the reliance on chemical fertilizers and pesticides, promoting sustainable agriculture. By manipulating root exudates, we can improve soil health, increase crop productivity, and support sustainable farming practices in a changing climate. As global agriculture faces challenges from soil degradation, climate variability, and food security demands, root exudates offer an eco-friendly approach to enhancing soil fertility, boosting plant resilience, and reducing agricultural inputs, thus contributing to more sustainable and resilient agroecosystems.
Dissertations / Theses on the topic "Root exudates"
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Curnow, Philip Kenneth. "Influence of root exudates on rhizosphere pseudomonads." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286230.
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Shi, Shengjing. "Influence of root exudates on soil microbial diversity and activity." Lincoln University, 2009. http://hdl.handle.net/10182/1549.
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Interactions between plant roots and soil microorganisms in the rhizosphere are critical for plant growth. However, understanding of precisely how root exudates influence the diversity and activity of rhizosphere microorganisms is limited. The main objective of this study was to investigate the effect of radiata pine (Pinus radiata) root exudates on rhizosphere soil microbial communities, with an emphasis on the role of low molecular weight organic anions. The study involved the development and validation of new methods for investigating rhizosphere processes in a purpose-built facility. This included development of an in situ sampling technique using an anion exchange membrane strip to collect a range of organic anions exuded from radiata pine roots grown in large-scale rhizotrons. These included tartarate, quinate, formate, malate, malonate, shikimate, lactate, acetate, maleate, citrate, succinate and fumarate. Soil microbial activity and diversity were determined using dehydrogenase activity and denaturing gradient gel electrophoresis. Links between organic anions in root exudates and rhizosphere soil microbial community structures were investigated by comparing wild type and genetically modified radiata pine trees which were grown in rhizotrons for 10 months. As expected, there was considerable temporal and spatial variability in the amounts and composition of organic anions collected, and there were no consistent or significant differences determined between the two tree lines. Significant differences in rhizosphere microbial communities were detected between wild type and genetically modified pine trees; however, they were inconsistent throughout the experiment. The shifts in microbial communities could have been related to changes in exudate production and composition. Based on results from the main rhizotron experiment, a microcosm study was carried out to investigate the influence of selected pine root exudate sugars (glucose, sucrose and fructose) and organic anions (quinate, lactate and maleate) on soil microbial activity and diversity. Soil microbial activity increased up to 3-fold in all of the sugar and organic anion treatments compared to the control, except for a mixture of sugars and maleate where it decreased. The corresponding impacts on soil microbial diversity were assessed using denaturing gradient gel electrophoresis and 16S rRNA phylochips. Addition of the exudate compounds had a dramatic impact on the composition and diversity of the soil microbial community. A large number of bacterial taxa (88 to 1043) responded positively to the presence of exudate compounds, although some taxa (12 to 24) responded negatively. Organic anions had a greater impact on microbial communities than sugars, which indicated that they may have important roles in rhizosphere ecology of radiata pine. In addition, a diverse range of potentially beneficial bacterial taxa were detected in soil amended with organic anions, indicating specific regulation of rhizosphere microbial communities by root exudates. This project highlighted the considerable challenges and difficulties involved in detailed investigation of in situ rhizosphere processes. Nonetheless, the findings of this study represent a significant contribution to advancing understanding of relationships between root exudates and soil microbial diversity, which will be further enhanced by refinement and application of the specific methodologies and techniques developed.
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Vives, Peris Vicente. "Interaction of citrus root exudates with plant growth promoting rhizobacteria under abiotic stress conditions." Doctoral thesis, Universitat Jaume I, 2018. http://hdl.handle.net/10803/461915.
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En la naturaleza las plantas liberan constantemente a la rizosfera una mezcla de metabolitos conocida como exudados radiculares. Su composición puede verse afectada por diferentes estímulos, incluyendo estreses abióticos como la salinidad o elevadas temperaturas. El Capítulo 1 demuestra que los portainjertos de cítricos citrange Carrizo y Citrus macrophylla exudan diferentes concentraciones de prolina y fitohormonas dependiendo del estrés abiótico y del genotipo. El Capítulo 2 estudia el efecto de dichos exudados de plantas de cítricos sometidas a salinidad y calor sobre las rizobacterias Pseudomonas putida KT2440 y Novosphingobium sp. HR1a, los cuales generalmente promueven su crecimiento. Además, se detectó la presencia de prolina y salicilatos en exudados a través del análisis de la expresión de los promotores PputA y PpahA de P. putida KT2442 y Novosphingobium sp. HR1a respectivamente. Finalmente, el Capítulo 3 muestra el efecto beneficioso de ambas bacterias en plantas de C. macrophylla sometidas a salinidad.In nature, plants are constantly releasing a mixture of metabolites through the roots known as root exudates. Its composition can be affected by different stimuli, including abiotic stress conditions as salinity or high temperatures. Chapter 1 demonstrates that citrus rootstocks Carrizo citrange and Citrus macrophylla exude different concentrations of proline and phytohormones depending on the abiotic stress condition and the genotype. Chapter 2 studies the effect of citrus root exudates from salt- and heat-stressed plants on the rhizobacteria Pseudomonas putida KT2440 and Novosphingobium sp. HR1a, which generally promote their growth. Moreover, the presence of proline and salicylates in root exudates was also tested through the analyses of the expression of the promoters PputA and PpahA of P. putida KT2442 and Novosphingobium sp. HR1a, respectively. Finally, Chapter 3 reveals the beneficial effect of both bacterial strains in C. macrophylla plants subjected to salt stress conditions.
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Henry, Amelia. "Effect of Drought, Flooding, and Potassium Stress on the Quantity and Composition of Root Exudates in Axenic Culture." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/5633.
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Root exudates include important chelating compounds and can change the rhizosphere pH by several units. These changes are essential for nutrient uptake and can also alter solubility of soil contaminants and increase plant uptake. Mild root-zone stress may increase exudation and more severe stress can damage membranes and increase root turnover, all of which increase root-zone carbon. Increased carbon from this rhizodeposition can increase microbial activity, which might help degrade contaminants. We studied the effect of three types of stress on root exudation of crested wheatgrass (Agropyron cristatum): low K+, drought, and flooding. These stresses were compared to two types of controls: 100% NO3- and high NH4+:NO3- ratio. We developed an improved axenic system to keep plants microbe-free for 70 days while analyzing exudates for total organic carbon (TOC) and organic acids. Axenic conditions were confirmed by plate counts of the leachate and microscopic observations of the leachate and roots. Optimal conditions for plant growth were maintained by monitoring temperature, light, humidity, water, O2, CO2, nutrient availability, and root-zone pH. Plants were grown in Ottawa sand that was layered by size to optimize water availability. Total organic carbon released over the 70-day growth period in mg per gram dry plant was 2.6 in the control, 2.3 in the NH4+ treatment, 3.7 in the flood and K+ stress treatments, and 4.4 in the drought treatment, which was the only treatment significantly higher than controls (p = 0.05). TOC and organic acid levels in the exudates peaked before the end of the study. The peak TOC levels, expressed as mg TOC per gram new dry plant mass, were 1.9 in the control, 3.0 in the NH4+ treatment, 2.9 in the flood, and 5.8 in the drought and K+ stress treatments. Organic acids were measured by gas chromatography-mass spectrometry (GC-MS). Malic acid was the predominant organic acid, and accounted for the majority of the TOC in the drought treatment. Oxalic, succinic, fumaric, and malonic acids accounted for less than 10% of the TOC. These data indicate that stress may enhance phytoremediation by changing root-zone exudate composition.
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Medina, Rachel Morales. "Investigation of Maize Root Exudates on Heterodera glycines Populations under Direct and Indirect Exposure." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1482499805741097.
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Curlango-Rivera, Gilberto. "Function of Root Border Cells and their Exudates on Plant Defense in Hydroponic Systems." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202535.
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Controlled environment agriculture offers a solution to challenges including less available land, water deficits, and consumer demand for pesticide free produce. However, control of soil-borne diseases is a major limiting factor. The goal of this dissertation was to examine predictions of the hypothesis that border cells function to protect plant health by controlling microorganisms associated with plants grown in hydroponic culture. Border cells separate from root tips upon immersion in water, and appear to have important roles in the defense mechanisms of plant roots. The general objectives were (1) to study the delivery of border cells in hydroponics; (2) to evaluate interactions between border cells and microorganisms in hydroponics; and (3) to explore approaches to alter border cell production for improved root disease control. In this study it was confirmed that border cells can be released continuously into the solution of hydroponic culture suggesting that plants grown in this system may use extra energy in the production of new border cells. Free border cells interacted with microorganisms present in the hydroponic solution by secreting an extracellular capsule. Previous studies showed that proteins are a key component of this capsule, including lectins. The interaction of pea lectin and Nectria haematococca spores therefore was explored. Results demonstrated that pea lectin agglutinates fungal spores in a hapten-specific manner, and inhibits their germination. Lectin had no negative effect on root development suggesting that it could be used as a potential control for soil-borne diseases in hydroponics. To control the production of border cells, subsequent studies measured the impact of a transient exposure of root tips to different metabolites secreted by root caps and border cells. Exposure to specific metabolites altered the production of border cells without measurable effects on root growth and development. This is in contrast to results obtained with altered gene expression. For example, gene silencing of a border cell specific gene resulted in altered root growth.
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Sun, Lijuan. "Study on the mechanisms of rhizosphere priming effects induced by root exudates in a temperate broad-leaved forest." Kyoto University, 2018. http://hdl.handle.net/2433/232351.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第21150号
農博第2276号
新制||農||1059(附属図書館)
学位論文||H30||N5124(農学部図書室)
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 北山 兼弘, 教授 小杉 緑子, 教授 本田 与一
学位規則第4条第1項該当
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Kierul, Kinga. "Comprehensive proteomic study of Bacillus amyloliquefaciens strain FZB42 and its response to plant root exudates." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16805.
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Bacillus amyloliquefaciens FZB42 ist ein frei lebendes Bakterium, das Pflanzenwurzeln besiedelt und das Pflanzenwachstum durch viele verschiedene Wirkmechanismen anregt. In dieser Arbeit wurden die molekularen Grundlagen dieser positiven Wirkungen, die dieses „Pflanzenwachstum fördernde Rhizobakterium“ (PGPR) auf seine Wirte ausübt, untersucht. Um den gegenseitigen Austausch von B. amyloliquefaciens und seinen Wirtspflanzen zu entschlüsseln, wurden umfangreiche Proteomstudien durchgeführt. Es wurden Referenzkarten der extrazellulären und zytosolischen Proteinfraktionen erstellt. Die größte Anzahl an ausgeschiedenen Proteinen konnte während der stationären Phase beobachtet werden. Die identifizierten extrazellulären Proteine gehören verschiedenen Funktionsklassen an, wobei die prominentesten Klassen am Kohlenhydrat-Abbau und den Transport von Molekülen durch die Zellwand beteiligt sind. Die zytosolischen Extrakte von Kulturen, die in 1C-Medium bzw. Mineralmedium angezogen wurden, und in der zweidimensionalen Gelelektrophorese (2 DE) aufgetrennt wurden, ergaben 461 und 245 verschiedene Protein-Einträge. Die erstellten Referenz-Karten wurden anschließend verwendet, um Proteine und Prozesse, in an der Interaktion mit Pflanzen beteiligt sind, zu identifizieren. Dafür wurden die Bakterien Wurzelexudaten von Mais (Zea mays L.) ausgesetzt. Die Proteine aus zwei Stämmen, denen die globalen Transkriptionsregulatoren (Degu, AbrB) und vier Sigma-Faktoren (SigB, SigM, SigV, und SigX) fehlen, wurden ebenfalls untersucht, um ihre Beteiligung an den bakteriellen Reaktionen auf die Wurzelausscheidungen zu analysieren. Zusammenfassend ist dies die erste Studie, die umfangreiche Proteomdaten von Gram-positiven PGPR präsentiert, wobei gleichzeitig die Veränderung der Expression von extrazellulären und zytoplasmatischen Proteinen, nach Zugabe von Wurzelexudaten, ausgewertet wurde.Bacillus amyloliquefaciens strain FZB42 is a free-living bacterium that competitively colonizes plant roots and stimulates plant growth by many different modes of action. The molecular basis of singular beneficial effects that this Plant Growth-Promoting Rhizobacteria (PGPR) exert on their hosts have been studied. To decipher the molecular cross-talk of B. amyloliquefaciens and its’ host plants as a whole system, an extensive proteomic approach was performed. Reference maps of the extracellular and cytosolic protein fractions were established. The highest number of secreted proteins was observed during stationary growth phase. Identified extracellular proteins belong to different functional classes, with the most prominent classes involved in carbohydrate degradation and transportation of molecules across the cell wall. Cytosolic extracts obtained from cultures grown in 1C and minimal media subjected to the 2 Dimensional Electrophoresis (2 DE), revealed 461 and 245 different protein entries, respectively. Created reference maps were subsequently used to identify proteins and processes involved in the interaction with plants, prior to exposure of bacteria to maize (Zea mays L.) root exudates. The proteomics of two strains lacking expression of genes coding for global transcriptional regulators (degU, abrB) and four sigma factors (sigB, sigM, sigV, and sigX) were also inves-tigated, in order to analyse their involvement in bacterial responses to root exudates. In summary, this is the first study presenting comprehensive proteomics of Gram-positive PGPR, evaluating at the same time changes in protein expression caused by addition of root exudates at the extracellular and cytosolic level.
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Morris, Kendalynn A. "Nitrogen Cycling in the Rhizosphere of Cheatgrass and Crested Wheatgrass: Contributions of Root Exudates and Senescence." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3566.
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Cheatgrass is an invasive weed that has come to dominate large areas of the western United States. Once an ecosystem has been converted to a cheatgrass monoculture, it is extremely difficult to restore native vegetation. Cheatgrass negatively impacts wildlife and increases wildfire frequency and intensity. Understanding how cheatgrass so effectively invades western ecosystems is essential to turning the tide of invasion. One possible key to cheatgrass’ success is alteration of soil nutrient cycling. The goal of this study is to explore how nitrogen (N) may accumulate in cheatgrass soils via redistribution of N within soil N pools. To accomplish this we investigated soil N cycling in soils underneath cheatgrass and crested wheatgrass. We used a 15N isotope tracer to determine the contribution of root exudates to soil N pools. During the 1-week 15N tracer experiment, cheatgrass roots exuded more than twice as much N (0.11 mg N kg-1 soil d-1) as crested wheatgrass roots (0.05 mg N kg-1 soil d-1). We propose that exudation of high N content root exudates leads to the changes in soil N pool size and transformation rates commonly observed in soils under cheatgrass. This research uses a simple and relatively inexpensive isotope tracer to shed light on mechanisms by which invasive plants may alter soil processes. By understanding these mechanisms we may be able to develop strategies for better managing cheatgrass invasion.
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Heim, Alexander. "Chelating organic substances in roots and root exudates and their potential role in aluminium resistance of Norway Spruce (Picea abies (L.) Karst.) /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13807.
Full textBooks on the topic "Root exudates"
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Heim, Alexander. Chelating organic substances in roots and root exudates and their potential role in aluminum resistance of Norway spruce (Picea abies [L.] Karst.). 2000.
Find full textBook chapters on the topic "Root exudates"
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Curl, Elroy A., and Bryan Truelove. "Root Exudates." In Advanced Series in Agricultural Sciences, 55–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-70722-3_3.
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Inderjit and L. A. Weston. "Root Exudates: an Overview." In Root Ecology, 235–55. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-09784-7_10.
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Rasmann, Sergio, Eva Oburger, and Ivan Hiltpold. "Root Exudates Mediate Plant-Environment Interactions." In Plant Roots, 467–82. 5th ed. Boca Raton: CRC Press, 2024. http://dx.doi.org/10.1201/b23126-37.
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Friebe, Annette, Wilma Klever, Richard Sikora, and Heide Schnabl. "Allelochemicals in Root Exudates of Maize." In Phytochemical Signals and Plant—Microbe Interactions, 71–93. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5329-8_5.
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POPE, DANIEL F., A. C. THOMPSON, and A. W. COLE. "The Effect of Root Exudates on Soybeans." In ACS Symposium Series, 235–41. Washington, D.C.: American Chemical Society, 1985. http://dx.doi.org/10.1021/bk-1985-0268.ch016.
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Balasubramanian, V., Arunima Sur, Kush Kumar Nayak, and Ravi Kant Singh. "Plant Root Exudates as Determinant of Rhizomicrobiome." In Rhizosphere Microbes, 105–26. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-9154-9_4.
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Randall, Peter J., Julie E. Hayes, Peter J. Hocking, and Alan E. Richardson. "Root Exudates in Phosphorus Acquisition by Plants." In Plant Nutrient Acquisition, 71–100. Tokyo: Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-66902-9_3.
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Deshpande, Aparna, Ana Clara Pontaroli, Srinivasa R. Chaluvadi, Fang Lu, and Jeffrey L. Bennetzen. "Plant Genetics for Study of the Roles of Root Exudates and Microbes in the Soil." In Root Genomics, 99–111. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-85546-0_4.
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Biate, David L., Annu Kumari, K. Annapurna, Lakkineni Vithal Kumar, D. Ramadoss, Kiran K. Reddy, and Satish Naik. "Legume Root Exudates: Their Role in Symbiotic Interactions." In Plant Microbes Symbiosis: Applied Facets, 259–71. New Delhi: Springer India, 2014. http://dx.doi.org/10.1007/978-81-322-2068-8_13.
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Delhaize, Emmanuel. "The Role of Root Exudates in Aluminum Tolerance." In Plant Nutrient Acquisition, 140–55. Tokyo: Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-66902-9_6.
Full textConference papers on the topic "Root exudates"
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Shaposhnikov, A. I., N. A. Vishnevskaya, V. Yu Shakhnazarova, D. S. Syrova, E. V. Borodina, O. N. Kovaleva, and O. K. Strunnikova. "Features of the initial stages of the relationship between barley, phytopathogenic fungus Fusarium culmorum and rhizobacteria Pseudomonas fluorescens 2137." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.219.
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It was shown that enhanced colonization of barley's roots by Fusarium culmorum in the presence of Pseudomonas fluorescens 2137 may be due to the composition of root exudates. Strain 2137 can enhance expression of plant defence gene PAL.
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Wang, Lin, Li Wang, and Chunxiao Sun. "The Effect of BPA on Reed Root Exudates." In 2nd International Conference on Material Science, Energy and Environmental Engineering (MSEEE 2018). Paris, France: Atlantis Press, 2018. http://dx.doi.org/10.2991/mseee-18.2018.16.
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Jianchao Zhou, Xiaochun Wang, Yanhong Deng, and Yan Wang. "Effects of phosphorus stress on the root morphology and root exudates in different sugar beet genotypes." In 2011 International Conference on Remote Sensing, Environment and Transportation Engineering (RSETE). IEEE, 2011. http://dx.doi.org/10.1109/rsete.2011.5964484.
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Moran, James, Timothy Linley, Jason Kriesel, Elizabeth Denis, Peter Ilhardt, and James Kelly. "Spatially Resolved Carbon Isotope Measurements for Tracing Root Exudates into the Rhizosphere." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1843.
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"Effect of root exudates and rhizobacteria on colonization of barley roots by phytopathogenic fungi Fusarium culmorum." In Plant Genetics, Genomics, Bioinformatics, and Biotechnology. Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 2019. http://dx.doi.org/10.18699/plantgen2019-161.
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Hosseinzadeh, Seyedahmad. "ADSORPTION OF ROOT EXUDATES ONTO CORN STRAW-DERIVED BIOCHAR: CHARACTERIZATION AND ADSORPTION ISOTHERM STUDIES." In 49th International Academic Conference, Dubrovnik. International Institute of Social and Economic Sciences, 2019. http://dx.doi.org/10.20472/iac.2019.049.020.
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Frémont, Adrien. "White Lupin (L. albus) Root Exudates Profiling Reveal New Potential Mechanisms for Arsenic Phytoremediation." In ASPB PLANT BIOLOGY 2020. USA: ASPB, 2020. http://dx.doi.org/10.46678/pb.20.1052926.
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Guo, Ping, Jin Wang, Chunli Kang, Weiwei Chen, Tao Chen, and Xueyu Lin. "Studies on the Properties of Root Exudates and Their Effects on Solubility of Pentachlorophenol (PCP)." In 2009 3rd International Conference on Bioinformatics and Biomedical Engineering (iCBBE). IEEE, 2009. http://dx.doi.org/10.1109/icbbe.2009.5163444.
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Guo, Ping, Jin Wang, Chunli Kang, Weiwei Chen, Tao Chen, and Xueyu Lin. "The Effects on Solubility of PCP by Sunflower (Helianthus Annuus) Root Exudates in Different Environmental Conditions." In 2009 3rd International Conference on Bioinformatics and Biomedical Engineering (iCBBE). IEEE, 2009. http://dx.doi.org/10.1109/icbbe.2009.5163605.
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Hosseinzadeh, Seyedahmad. "Closed hydroponic systems: a kinetic study for the adsorption of root exudates on GAC and SMC." In 5th International Conference on Innovation in Science and Technology. acavent, 2018. http://dx.doi.org/10.33422/5ist.2018.12.103.
Full textReports on the topic "Root exudates"
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Phillips, Donald A., Yitzhak Spiegel, and Howard Ferris. Optimizing nematode management by defining natural chemical bases of behavior. United States Department of Agriculture, November 2006. http://dx.doi.org/10.32747/2006.7587234.bard.
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This project was based on the hypothesis that nematodes interacting with plants as either parasites or beneficial saprophytes are attracted to their host by natural products. This concept was supported by numerous observations that parasitic nematodes are attracted to root exudates. Our overall goal was to identify nematode sensory compounds from root exudates and to use that information for reducing nematicide applications. We applied skills of the investigators to achieve three specific objectives: 1) Identify nematode behavioral cues (e.g., attractants or repellents) in root exudates; 2) Identify new natural nematicidal compounds; and 3) Combine a natural attractant and a nematicide into a nematode trap. Because saprophytic nematodes benefit plants by mineralizing organic matter, we sought compounds attractive primarily to parasitic nematodes. The project was constructed on several complementary foundations. First, data from Dr. Spiegel’s lab showed that under aseptic conditions Ditylenchus dipsaci, a parasite on onion, is attracted to certain fractions of onion root exudates. Second, PI Phillips had a sizeable collection of natural plant products he had identified from previous work on Rhizobium-legume interactions, which could be tested “off the shelf”. Third, Dr. Ferris had access to aseptic and natural populations of various saprophytic and parasitic nematodes. The project focused on five nematode species: D.dipsaci, Heterodera avenae, and Tylenchulussemipenetransat ARO, and Meloidogyne javanicand Caenorhabditis elegans at UCD. Ten pure plant compounds, mostly flavonoids, were tested on the various nematode species using six different assay systems. Results obtained with assorted test systems and by various scientists in the same test systems were essentially irreproducible. Many convincing, Many convincing, i.e. statistically significant, results in one system or with one investigator could not be repeated with other assays or different people. A recent report from others found that these compounds, plus another 30, were inactive as attractants in three additional parasitic nematode species (Wuyts et al. Nematology 8:89- 101, 2006). Assays designed to test the hypothesis that several compounds together are required to attract nematodes have thus far failed to find a reproducibly active combination. In contrast to results using pure plant compounds, complex unfractionated exudates from aseptic onion root reproducibly attracted D. dipsaci in both the ARO and UCD labs. Onion root exudate collection, separation into HPLC fractions, assays using D. dipsaci and MS-MS experiments proceeded collaboratively between ARO and UCD without any definitive identification of an active compound. The final active fraction contained two major molecules and traces of several other compounds. In the end, analytical studies were limited by the amount of onion root exudate and the complexity of the purification process. These tests showed that aseptic plant roots release attractant molecules, but whether nematodes influence that release, as insects trigger release of attractants from plants, is unknown. Related experiments showed that the saprophyte C. elegans stimulates its prey, Pseudomonas bacteria, to increase production of 2, 4-diacetylphloroglucinol (DAPG) a compound that promotes amino acid exudation by plant roots. It is thus possible that saprophytic nematodes are attracted primarily to their bacterial or fungal prey and secondarily to effects of those microorganisms on root exudation. These observations offer promising avenues for understanding root-zone interactions, but no direct routes to controlling nematodes in agriculture were evident. Extracts from two plant sources, Chrysanthemum coronarium and Sequoia sempervirens, showed nematicidal activity at ARO and UCD, respectively. Attempts to purify an active compound from S. sempervirens failed, but preliminary results from C. coronarium are judged to form a potential basis for further work at ARO. These results highlight the problems of studying complex movement patterns in sentient organisms like nematodes and the issues associated with natural product isolation from complex mixtures. Those two difficulties combined with complications now associated with obtaining US visas, slowed and ultimately limited progress on this project. As a result, US investigators expended only 65% of the $207,400 originally planned for this project. The Israeli side of the project advanced more directly toward its scientific goals and lists its expenditures in the customary financial report.
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Powell, Samantha, Daisy Herrera, Irina El Khoury, Cayden Perdue, Natalie Sadler, John Cort, Grace Robinson, Pubudu Handakumbura, James Evans, and Vivian Lin. Accelerating the identification of novel secondary metabolites in bioenergy plant root exudates using MicroED. Office of Scientific and Technical Information (OSTI), September 2024. http://dx.doi.org/10.2172/2452767.
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Kapulnik, Yoram, Maria J. Harrison, Hinanit Koltai, and Joseph Hershenhorn. Targeting of Strigolacatones Associated Pathways for Conferring Orobanche Resistant Traits in Tomato and Medicago. United States Department of Agriculture, July 2011. http://dx.doi.org/10.32747/2011.7593399.bard.
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This proposal is focused on examination of two plant interactions: parasitic with Orobanche, and symbiosis with arbuscular mycorrhiza fungi (AMF), and the involvement of a newly define plant hormones, strigolactones (SLs), in these plant interactions. In addition to strigolactones role in regulation of above-ground plant architecture, they are also known to be secreted from roots, and to be a signal for seed germination of the parasitic plants Orobanche. Moreover, secreted strigolactones were recognized as inducers of AMFhyphae branching. The present work was aimed at Generation of RNAi mutants of both tomato and Medicago, targeting multiple genes that may be involved in strigolactone production, carotenoid biosynthesis pathway, Pi signaling or other metabolic pathways, and hence affect AMF colonization and/or Orobanche resistance. Following the newly formed and existing RNAi mutants were examined for AMF colonization and Orobanche resistance. At the first phase of this project Orobanche seed germination assays and AMF colonization were examined in intact plants. These assays were shown to be effective and resulted with enhancement of Orobanche seed germination and AMF colonization in WT tomato plants, whereas roots of strigolactones impaired lines did not result with Orobanche seed germination and mycorrhiza colonization. Unexpectedly, root organ cultures (ROC) that were produced from the same wild type (WT) and mutant lines did not induce the Orobanche seed germination and AMFhyphal branching. This implies that under in vitro conditions ROC cultures are missing an important component for induction of Orobanche seed germination and AMFhyphal branching. In another line of experiments we have tested transgenic lines of Medicagotruncatula for AMFhuyphal branching and Orobanche seed germination assays. These lines included lines silenced for a GRAS transcription factor (RNAi 1845), an NBS-LRR type resistance gene (RNAi 1847), a kinase (RNAi 2403) and a protein of unknown function (RNAi 2417). In all cases, five independent transgenic root lines showed altered AMFphenotypes with reduced or aberrant colonization patterns. Following, we transformed tomato plants with the M. truncatulaTC 127050 PhosphoinositidekinaseRNAi construct. Transgenic lines that contained GUS constructs were used as control. All transgenic lines showed reduced level of Orobanche seed germination, masking any strigoalctones-specific effect. The research demonstrated that SLs production may not be examined in ROC –based bioassays. It was shown by the 3 independent assays employed in this project that none of the recognized characters of SLs may be reflected in these bioassays. However, when the whole plant root exudates were examined, SLs activity in root exudates was demonstrated. Hence, it can be concluded that the presence of an intact shoot, and possibly, shoot factors, may be necessary for production of SLs in roots. Another point of interest that rises from these results is that the presence of SLs is not necessary for AMF completion of life cycle. Hence, it may be concluded that SLs are important for AMFhyphal branching, before symbiosis, but not essential for AMF colonization and life cycle completion under ROC system conditions.
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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova, and Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604286.bard.
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The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.
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Hackett, Wesley, Michael Raviv, Anath Das, Oded Reuveni, and Arie Gutman. Detecting Activity of Juvenile Phase-Specific Translocatable Substances that Influence Rooting Potential Using In Vitro Rooting Assays and Expression of a Specific Gene. United States Department of Agriculture, April 1998. http://dx.doi.org/10.32747/1998.7613038.bard.
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The objectives of the project for which substantial effort was put forth were to: 1) Verify the relationship between expression of a cDNA clone (HW103) and the rooting potential of reciprocally grafted cuttings of juvenile and mature lamina and petioles of Hedera helix L. 2) Detect rooting promoter fractions in exudates from the juvenile leaves of H. Helix by assaying for rooting with leaf petioles of juvenile and mature plants. 3) Isolate, purify and identify compounds which show activity in assays for rooting potential. Some objectives or aspects of the objectives of the original proposal were not pursued for the reasons put forth in the body of the report. The most significant findings of the project are: 1) The MS medium is a better medium than Romberg medium for performing the leaf petiole rooting assay. 2) HW103 gene expression is cell-type specific with higher levels of expression in mature than juvenile phase H. Helix petioles as evidenced by in situ hybridization which suggests a negative relationship between HW103 expression in specific cells involved in root initiation and the lack of rooting potential in mature petioles 3) HW103 gene expression may be lower in mature petioles which had been grafter to a juvenile H. Helix lamina than mature petioles that had been grafted to a mature lamina and this putative lower expression is related to formation of a higher number of roots. 4) HW103 gene expression is not related to auxin induced ethylene production. 5) Two distinct compounds that possess root initiation promoting activity can be detected mainly in diffusate of juvenile H. Helix leaves using mung bean hypocotyls and H. Helix leaf petioles in vitro. 6) H. Helix diffusate active fractions do not insistenlty promote rooting in avocado mini-cuttings. 7) Chemical identification of the active rooting compounds was not accomplished because of the death of Prof. Becker, one of the collaborators, and the resultant loss of his data. These results indicate that these may be a molecular basis for reduced rooting potential in mature H. Helix petioles and that there are diffusible (translocatable) compounds in juvenile H. Helix leaves which promote rooting in juvenile and mature H. Helix petioles and mung bean hypocotyls.
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McClure, Michael A., Yitzhak Spiegel, David M. Bird, R. Salomon, and R. H. C. Curtis. Functional Analysis of Root-Knot Nematode Surface Coat Proteins to Develop Rational Targets for Plantibodies. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7575284.bard.
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The goal of this research was to provide a better understanding of the interface between root-knot nematodes, Meloidogyne spp., and their host in order to develop rational targets for plantibodies and other novel methods of nematode control directed against the nematode surface coat (SC). Specific objectives were: 1. To produce additional monoclonal SC antibodies for use in Objectives 2, 3, and 4 and as candidates for development of plantibodies. 2. To determine the production and distribution of SC proteins during the infection process. 3. To use biochemical and immunological methods to perturbate the root-knot nematode SC in order to identify SC components that will serve as targets for rationally designed plantibodies. 4. To develop SC-mutant nematodes as additional tools for defining the role of the SC during infection. The external cuticular layer of nematodes is the epicuticle. In many nematodes, it is covered by a fuzzy material termed "surface coat" (SC). Since the SC is the outermost layer, it may playa role in the interaction between the nematode and its surroundings during all life stages in soil and during pathogenesis. The SC is composed mainly of proteins, carbohydrates (which can be part of glycoproteins), and lipids. SC proteins and glycoproteins have been labeled and extracted from preparasitic second-stage juveniles and adult females of Meloidogyne and specific antibodies have been raised against surface antigens. Antibodies can be used to gain more information about surface function and to isolate genes encoding for surface antigens. Characterization of surface antigens and their roles in different life-stages may be an important step towards the development of alternative control. Nevertheless, the role of the plant- parasitic nematode's surface in plant-nematode interaction is still not understood. Carbohydrates or carbohydrate-recognition domains (CROs) on the nematode surface may interact with CROs or carbohydrate molecules, on root surfaces or exudates, or be active after the nematode has penetrated into the root. Surface antigens undoubtedly play an important role in interactions with microorganisms that adhere to the nematodes. Polyclonal (PC) and monoclonal (MC) antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes, were used to characterize the surface coat and secreted-excreted products of M. javanica and M. incognita. Some of the MC and PC antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Further characterization, in planta, of the epitopes recognized by the antibodies, showed that they were present in the parasitic juvenile stages and that the surface coat is shed during root penetration by the nematode and its migration between root cells. At the molecular level, we have followed two lines of experimentation. The first has been to identify genes encoding surface coat (SC) molecules, and we have isolated and characterized a small family of mucin genes from M. incognita. Our second approach has been to study host genes that respond to the nematode, and in particular, to the SC. Our previous work has identified a large suite of genes expressed in Lycopersicon esculentum giant cells, including the partial cDNA clone DB#131, which encodes a serine/threonine protein kinase. Isolation and predicted translation of the mature cDNA revealed a frame shift mutation in the translated region of nematode sensitive plants. By using primers homologous to conserved region of DB#131 we have identified the orthologues from three (nematode-resistant) Lycopersicon peruvianum strains and found that these plants lacked the mutation.