Deploying microbes as a seed treatment for protection against soil-borne plant pathogens Plant diseases, especially those caused by soil-borne seed infecting pathogens, pose a serious threat to the production of both greenhouse and field crops. Conventional farming operations often use fumigants and chemical seed treatments, which can be harmful to human health and the environment, for controlling seed and seedling pathogens. The use of many of these materials is strictly prohibited in organic agriculture, limiting the options for organic farmers for plant disease control. Organic amendments such as compost and vermicompost are used as alternatives to synthetic control methods due, in part, to their success in controlling plant pathogens. Previous studies have confirmed consistent disease suppression using solid and liquid forms of organic amendments and the working hypothesis is that microbes are closely associated with suppression. Furthermore, only a subset of microbes from the bulk material that colonize the seed coat are responsible for disease suppression. So if the specific subset of microbes associated with seed colonization and suppression can be deployed as a seed treatment, can we still achieve plant protection from soil-borne pathogens? In addition, can this seed treatment application be developed for organic production as an effective tool for disease management? The goal of this project is to establish a proof-of-concept that compost and vermicompost microbes can be applied to the surface of seeds before sowing to protect against soil-borne plant pathogens. Liquid extracts will be produced from solid materials, freeze-dried to a powder form, and applied to the seed coat. Treated seeds will first be evaluated for disease suppression under laboratory conditions, and then tested for use on certified organic land. The information generated from this project has the potential to introduce a novel seed-treatment application for controlling plant pathogens in organic production systems.
Biofortified Blog Biological Pest Control Basics Biofortified Blog Managing pests is an important part of cultivating plants whether you are tending a small garden in your yard or several fields of crops.
The interaction between Phytophthora pathogens and host plants involves the exchange of complex molecular signals from both sides. Recent studies of Phytophthora have led to the identification of various apoplastic elicitors known to trigger plant immunity. Here, we provide evidence that the protein encoded by OPEL of Phytophthora parasitica is a novel elicitor. Homologs of OPEL were identified only in oomycetes but not fungi and other organisms. Quantitative RT-PCR revealed that OPEL is expressed throughout development of P. parasiticaand is especially highly induced after plant infection. Infiltration of OPEL recombinant protein from E. coli into leaves of Nicotiana tabacum (cv. Samsun NN) resulted in cell death, callose deposition, production of reactive oxygen species, and induced expression of PAMP-triggered immunity markers and salicylic acid-responsive defense genes. Moreover, the infiltration conferred systemic resistance against a broad spectrum of pathogens including Tobacco mosaic virus, the bacteria wilt pathogen Ralstonia solanacearum, and P. parasitica. In addition to the signal peptide, OPEL contains three conserved domains: a thaumatin-like domain, a glycine-rich protein domain, and a glycosyl hydrolase (GH) domain. Intriguingly, mutation of a putative laminarinase active-site motif in the predicted GH domain abolished its elicitor activity, which suggests enzymatic activity of OPEL in triggering the defense response.
We have demonstrated that genomic selection in diverse wheat landraces for resistance to leaf, stem and strip rust is possible, as genomic breeding values were moderately accurate. Markers with large effects in the Bayesian analysis confirmed many known genes, while also discovering many previously uncharacterised genome regions associated with rust scores.
Genomic selection, where selection decisions are based on genomic estimated breeding values (GEBVs) derived from genome-wide DNA markers, could accelerate genetic progress in plant breeding. In this study, we assessed the accuracy of GEBVs for rust resistance in 206 hexaploid wheat (Triticum aestivum) landraces from the Watkins collection of phenotypically diverse wheat genotypes from 32 countries. The landraces were genotyped for 5,568 SNPs using an Illumina iSelect 9 K bead chip assay and phenotyped for field-based leaf rust (Lr), stem rust (Sr) and stripe rust (Yr) responses across multiple years. Genomic Best Linear Unbiased Prediction (GBLUP) and a Bayesian Regression method (BayesR) were used to predict GEBVs. Based on fivefold cross-validation, the accuracy of genomic prediction averaged across years was 0.35, 0.27 and 0.44 for Lr, Sr and Yr using GBLUP and 0.33, 0.38 and 0.30 for Lr, Sr and Yr using BayesR, respectively. Inclusion of PCR-predicted genotypes for known rust resistance genes increased accuracy more substantially when the marker was diagnostic (Lr34/Sr57/Yr18) for the presence-absence of the gene rather than just linked (Sr2). Investigation of the impact of genetic relatedness between validation and reference lines on accuracy of genomic prediction showed that accuracy will be higher when each validation line had at least one close relationship to the reference lines. Overall, the prediction accuracies achieved in this study are encouraging, and confirm the feasibility of genomic selection in wheat. In several instances, estimated marker effects were confirmed by published literature and results of mapping experiments using Watkins accessions.
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T. CATHARINES, Ontario - New research at Brock University could unlock the genetic secrets of a pest killing fungus, potentially leading to the development of new, safer pesticides for farmers.
Biologist Micheal Bidochka and his PHD student Scott Behie explored the strange, symbiotic relationship between plants and the fungus metarhizium.
"Metarhizium is used in agriculture as pest control," said Behie. "But like all natural pesticides, it takes too long (to be an effective commercial pesticide.) But now that we are learning the full story about this fungus we could be reaching a stage where we can manipulate its genetics and produce something that infect pests faster."
The work Behie has done uncovered that metarhizium does more than just protect its host plants from insects. It also helps feed the plant.
As it turns out the fungus helps feed nitrogen to the plant. In doing so, Behie said the fungus is helping the plant stay strong.
The question, he said, is why?
"Altruism is not really found in nature. The fungus is not doing this out of the goodness of its heart or anything like that," he said. "So part of what we are trying to find out is what the fungus gets out of this."
Understanding exactly how metarhizium, which is commonly found, behaves and why will go a long way to unlocking it's genetic secrets.
Once a fuller picture of what the fungus does is established, scientists can then begin to manipulate it to produce a faster acting pesticide that is practical for the agricultural sector.
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MANILA (REUTERS) - The Philippines said an insect infestation had damaged another 400,000 coconut trees over the past week and could spread to the key growing areas by the end of this year, severely crippling the country's most valuable...
Multiple independent gene transfers gave fungi ability to colonize plant roots.
A single gene from bacteria has been donated to fungi on at least 15 occasions. The discovery shows that an evolutionary shortcut once thought to be restricted to bacteria is surprisingly common in more complex, eukaryotic life.
Bacteria frequently trade genes back and forth with their neighbours, gaining abilities and traits that enable them to adapt quickly to new environments. More complex organisms, by contrast, generally have to make do with the slow process of gene duplication and mutation.
There are a few examples of gene swapping between eukaryotes — the domain of life that includes fungi, plants and animals — and even from bacteria to eukaryotes (see 'Bacterial gene helps coffee beetle get its fix'). But such events, known as horizontal gene transfer, were thought to be rare.
But Daniel Muller, a microbial ecologist at the University of Lyons in France, and his colleagues have cast doubt on that assumption after studying bacteria in the soil around the roots of plants. They found that the bacterial gene acdS, used to promote the growth of plant roots, was also present in several types of fungus. Their work is published today in Proceedings of the Royal Society B1.
Pittsburgh Post Gazette (blog) Succession planting helps beat the pests and extends the harvest Pittsburgh Post Gazette (blog) The pest chews on the leaves, but also spreads bacterial wilt, which will kill the plants.
In the course of plant evolution, there is an obvious trend toward an increased complexity of plant bodies, as well as an increased sophistication of plant behavior and communication. Phenotypic plasticity of plants is based on the polar auxin transport machinery that is directly linked with plant sensory systems impinging on plant behavior and adaptive responses. Similar to the emergence and evolution of eukaryotic cells, evolution of land plants was also shaped and driven by infective and symbiotic microorganisms. These microorganisms are the driving force behind the evolution of plant synapses and other neuronal aspects of higher plants; this is especially pronounced in the root apices. Plant synapses allow synaptic cell-cell communication and coordination in plants, as well as sensory-motor integration in root apices searching for water and mineral nutrition. These neuronal aspects of higher plants are closely linked with their unique ability to adapt to environmental changes.
Background and Aims Changes occurring in the macromolecular traits of cell wall components in elm wood following attack byOphiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), are poorly understood. The purpose of this study was to compare host responses and the metabolic profiles of wood components for two Dutch elm (Ulmus) hybrids, ‘Groeneveld’ (a susceptible clone) and ‘Dodoens’ (a tolerant clone), that have contrasting survival strategies upon infection with the current prevalent strain of DED.
Methods Ten-year-old plants of the hybrid elms were inoculated withO. novo-ulmi ssp. americana × novo-ulmi. Measurements were made of the content of main cell wall components and extractives, lignin monomer composition, macromolecular traits of cellulose and neutral saccharide composition.
Key Results Upon infection, medium molecular weight macromolecules of cellulose were degraded in both the susceptible and tolerant elm hybrids, resulting in the occurrence of secondary cell wall ruptures and cracks in the vessels, but rarely in the fibres. The 13C nuclear magnetic resonance spectra revealed that loss of crystalline and non-crystalline cellulose regions occurred in parallel. The rate of cellulose degradation was influenced by the syringyl:guaiacyl ratio in lignin. Both hybrids commonly responded to the medium molecular weight cellulose degradation with the biosynthesis of high molecular weight macromolecules of cellulose, resulting in a significant increase in values for the degree of polymerization and polydispersity. Other responses of the hybrids included an increase in lignin content, a decrease in relative proportions of D-glucose, and an increase in proportions of D-xylose. Differential responses between the hybrids were found in the syringyl:guaiacyl ratio in lignin.
Conclusions In susceptible ‘Groeneveld’ plants, syringyl-rich lignin provided a far greater degree of protection from cellulose degradation than in ‘Dodoens’, but only guaiacyl-rich lignin in ‘Dodoens’ plants was involved in successful defence against the fungus. This finding was confirmed by the associations of vanillin and vanillic acid with the DED-tolerant ‘Dodoens’ plants in a multivariate analysis of wood traits.
Monitoring over 40 per cent of the world's forests, the Joint UNECE/FAO Forestry and Timber Section is well placed to respond to threats posed to these crucial regions. Section Chief Paola Deda elucidates the role forests can ...
Oomycetes are a group of filamentous microorganisms that includes both animal and plant pathogens and causes major agricultural losses. Phytophthora species can infect most crops and plants from natural ecosystems. Despite their tremendous economic and ecologic importance, few effective methods exist for limiting the damage caused by these species. New solutions are required, and their development will require improvements in our understanding of the molecular events governing infection by these pathogens. In this study, we characterized the genetic program activated during penetration of the plant by the soil-borne pathogen Phytophthora parasitica.
Using all the P. parasitica sequences available in public databases, we generated a custom oligo-array and performed a transcriptomic analysis of the early events of Arabidopsis thaliana infection. We characterized biological stages, ranging from the appressorium-mediated penetration of the pathogen into the roots to the occurrence of first dead cells in the plant. We identified a series of sequences that were transiently modulated during host penetration. Surprisingly, we observed an overall down regulation of genes encoding proteins involved in lipid and sugar metabolism, and an upregulation of functions controlling the transport of amino acids. We also showed that different groups of genes were expressed by P. parasitica during host penetration and the subsequent necrotrophic phase. Differential expression patterns were particularly marked for cell wall-degrading enzymes and other proteins involved in pathogenicity, including RXLR effectors. By transforming P. parasitica with a transcriptional fusion with GFP, we showed that an RXLR-ecoding gene was expressed in the appressorium and infectious hyphae during infection of the first plant cell.
We have characterized the genetic program activated during the initial invasion of plant cells by P. parasitica. We showed that a specific set of proteins, including effectors, was mobilized for penetration and to facilitate infection. Our detection of the expression of an RXLR encoding gene by the appressorium and infection hyphae highlights a role of this structure in the manipulation of the host cells.
Forest Pest Seminar set Feb. 14 in Lufkin AgriLife Today “Weakened forests are more susceptible to insects, diseases and competing vegetation that lead to growth losses and often the death of large numbers of trees under environmental extremes,”...
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