Project description:Arbuscular mycorrhiza (AM) interactions between plants and Glomeromycota fungi primarily support phosphate aquisition of most terrestrial plant species. To unravel gene expression in Medicago truncatula root colonization by AM fungi, we used genome-wide transcriptome profiling based on whole mycorrhizal roots. We used GeneChips to detail the global programme of gene expression in response to colonization by arbuscular mycorrhizal fungi and in response to a treatment with phosphate and identified genes differentially expressed during this process.
Project description:Arbuscular mycorrhiza (AM) interactions between plants and Glomeromycota fungi primarily support phosphate aquisition of most terrestrial plant species. To unravel gene expression during early stages of Medicago truncatula root colonization by AM fungi, we used genome-wide transcriptome profiling based on mycorrhizal root fragments enriched for early fungal infection stages. We used Medicago GeneChips to detail the global programme of gene expression in response to early stages of colonization by arbuscular mycorrhizal fungi and identified genes differentially expressed during these early stages.
Project description:Roots of Arabidopsis thaliana do not engage in symbiotic association with mycorrhizal fungi but host taxonomically diverse fungal communities that influence health and disease states. We sequenced the genomes of 41 isolates representative of the A. thaliana root mycobiota for comparative analysis with 79 other plant-associated fungi. We report that root mycobiota members evolved from ancestors having diverse lifestyles and retained diverse repertoires of plant cell wall-degrading enzymes (PCWDEs) and effector-like small secreted proteins. We identified a set of 84 gene families predicting best endophytism, including families encoding PCWDEs acting on xylan (GH10) and cellulose (AA9). These genes also belong to a core transcriptional response induced by phylogenetically-distant mycobiota members in A. thaliana roots. Recolonization experiments with individual fungi indicated that strains with detrimental effects in mono-association with the host not only colonize roots more aggressively than those with beneficial activities but also dominate in natural root samples. We identified and validated the pectin degrading enzyme family PL1_7 as a key component linking aggressiveness of endophytic colonization to plant health.
Project description:Mutualistic symbionts are increasingly recognized as hidden players in plant-insect interactions. Understanding how symbionts affect plant responses to herbivory provides important insight into the fascinating complexity of terrestrial ecological networks and how we could specifically target symbionts to achieve sustainable pest management. Although the role of herbivore-associated symbionts is gaining increased attention in ecology of plant-insect interactions, how symbionts of members of higher trophic levels affect these interactions is poorly understood. The natural enemies of insect herbivores such as parasitic wasps that are used in biological pest control are associated with mutualistic symbionts (polydnaviruses) that they inject into the herbivore along with eggs in an event of parasitisation. We showed previously that polydnavirus-genes are expressed in the salivary glands of parasitized caterpillars suggesting that third-trophic level symbionts may alter the herbivore’s salivary composition and consequently, affect the way the herbivore interacts with the plant. By using a novel multidisciplinary approach that integrates molecular, chemical, behavioral and field ecology, the proposed project aims to manipulate the phenotype of caterpillars to study the effect of symbiotic viruses of third-trophic-level insects at the plant-herbivore interface. We will address this issue at different levels of biological organization, from plant gene expression to plant-mediated ecological consequences. The project will thereby provide novel fundamental insights into the hidden role played by parasitic wasp symbionts in plant responses to herbivory and these insights will generate important knowledge for pest management programs that focus on polydnaviruses as biological control agents.
Project description:Arbuscular mycorrhiza (AM) interactions between plants and Glomeromycota fungi primarily support phosphate aquisition of most terrestrial plant species. To unravel gene expression in Medicago truncatula root colonization by AM fungi, we used genome-wide transcriptome profiling based on whole mycorrhizal roots. We used GeneChips to detail the global programme of gene expression in response to colonization by arbuscular mycorrhizal fungi and in response to a treatment with phosphate and identified genes differentially expressed during this process. Medicago truncatula roots were harvested at 28 days post inoculation with the two different arbuscular mycorrhizal fungi Glomus intraradices (Gi-Myc) and Glomus mosseae (Gm-Myc) under low phosphate conditions (20 µM phosphate) or after a 28 days treatment with 2 mM phosphate in the absence of arbuscular mycorrhizal fungi (2mM-P). As a control, uninfected roots grown under low phosphate conditions (20 µM phosphate) were used (20miM-P). Three biological replicates consisting of pools of five roots were used for RNA extraction and hybridization on Affymetrix GeneChips.
Project description:Arbuscular mycorrhiza (AM) interactions between plants and Glomeromycota fungi primarily support phosphate aquisition of most terrestrial plant species. To unravel cell-type specific gene expression during late stages of Medicago truncatula root colonization by AM fungi, we used genome-wide transcriptome profiling based on laser-microdissected cells. We used Medicago GeneChips to detail the cell-type specific programme of gene expression in late stages of colonization by arbuscular mycorrhizal fungi and identified genes differentially expressed during these stages. Medicago truncatula Gaertn M-bM-^@M-^XJemalongM-bM-^@M-^Y genotype A17 plantlets were grown in the climate chamber. Plants grown for the collection of root cortical cells containing arbuscules (ARB), root cortical cells from mycorrhizal roots (CMR), and root epidermal cells from mycorrhizal roots (EPI) were mycorrhized after 2 weeks with Glomus intraradices and mycorrhizal roots were harvested at around 21 days post inoculation (dpi).
Project description:Many of the microorganisms that are normally present in the soil, actually inhabit the rhizosphere and interact with plants. Those plant–microorganisms interactions may be beneficial or harmful. Among the first are the arbuscular mycorrhizal fungi (AMF). These soil fungi have been reported to improve plant resistance/tolerance to pests and diseases. On the other hand, soilborne pathogens represent a threat to agriculture generating important yield losses, depending upon the pathogen and the crop. One example is the “Sudden Death Syndrome” (SDS), a severe disease in soybean (Glycine max (L.) Merr) caused by a complex of at least four species of Fusarium sp., among which Fusarium virguliforme and F. tuccumaniae are the most prevalent in Argentina. This study provides, under strict in vitro culture conditions, a global analysis of transcript modifications in mycorrhizal and non-mycorrhizal soybean root associated with F. virguliforme inoculation. Microarray results showed qualitative and quantitative changes in the expression of defense-related genes in mycorrhizal soybean, suggesting that AMF are good candidates for sustainable plant protection against F. virguliforme.