Project description:Trichoderma spp. are versatile opportunistic plant symbionts which can colonize the apoplast of plant roots. Microarrays analysis of Arabidopsis thaliana roots inoculated with Trichoderma asperelloides T203, coupled with qPCR analysis of 137 stress-responsive genes and transcription factors, revealed wide gene transcript reprogramming, preceded by a transient repression of the plant immune responses supposedly to allow root colonization. Enhancement in the expression of WRKY18 and 40, which stimulate JA-signaling via suppression of JAZ repressors and negative-regulate the expression of the defense genes FMO1, PAD3 and CYP71A13, was detected in Arabidopsis roots upon Trichoderma colonization. Reduced root colonization was observed in the wrky18/wrky40 double mutant line, while partial phenotypic complementation was achieved by over-expressing WRKY40 in the wrky18 wrky40 background. On the other hand, an increased colonization rate was found in roots of the FMO1 knockout mutant. Two-condition experiment: Roots treated with Trichoderma vs. Control untreated roots. Biological replicates: 2 control replicates, 2 treated replicates. 1 dye-swap.
Project description:Trichoderma spp. are versatile opportunistic plant symbionts which can colonize the apoplast of plant roots. Microarrays analysis of Arabidopsis thaliana roots inoculated with Trichoderma asperelloides T203, coupled with qPCR analysis of 137 stress-responsive genes and transcription factors, revealed wide gene transcript reprogramming, preceded by a transient repression of the plant immune responses supposedly to allow root colonization. Enhancement in the expression of WRKY18 and 40, which stimulate JA-signaling via suppression of JAZ repressors and negative-regulate the expression of the defense genes FMO1, PAD3 and CYP71A13, was detected in Arabidopsis roots upon Trichoderma colonization. Reduced root colonization was observed in the wrky18/wrky40 double mutant line, while partial phenotypic complementation was achieved by over-expressing WRKY40 in the wrky18 wrky40 background. On the other hand, an increased colonization rate was found in roots of the FMO1 knockout mutant.
Project description:Numerous Trichoderma strains are beneficial for plants, promote their growth and confer stress tolerance. A recently described novel Trichoderma strain strongly promotes growth of Arabidopsis thaliana seedlings on media with 50 mM NaCl, while 150 mM NaCl strongly stimulated root colonization and induced salt-stress tolerance in the host without growth promotion. To understand the dynamics of plant-fungus interaction, we examined the secretome from both sides, and revealed a substantial change under different salt regimes, and during co-cultivation. Stress-related proteins, such as fungal Kp4-, WSC- and CFEM-domain-containing proteins, the plant calreticulin and cell-wall modifying enzymes, disappear when the two symbionts are co-cultured under high salt concentrations. More proteins involved in plant and fungal cell wall modifications and the battle of root colonization are found in the co-cultures under salt stress, while the number of plant antioxidant proteins decreased. We identified symbiosis- and salt concentration-specific proteins for both partners. The Arabidopsis PYK10 and a fungal prenylcysteine lyase are only found in the co-culture which promoted plant growth. The comparative analysis of the secretomes suggests that both partners profit from the interaction under salt stress but have to invest more in balancing the symbiosis. We discuss the role of the identified stage- and symbiosis-specific fungal and plant proteins for salt-stress and conditions promoting root colonization and plant growth.
Project description:Trichoderma species promote growth and strengthen immunity of Arabidopsis and crop species through multiple mechanisms. However, how fungal proteins mediate growth-defense tradeoffs is unknown. We analyzed the growth, root architecture, defense and global gene expression profiles in Arabidopsis seedlings co-cultivated with T. atroviride WT, and Δnox1, Δnox2, and ΔnoxR mutants, defective on the catalytic and regulatory subunits of NADPH oxidase, respectively. The gene expression profile in the fungus was also characterized in standard growth conditions and in the presence of plants. The results revealed the critical role of Trichoderma NoxR in mediating growth-defense tradeoffs in Arabidopsis. The effects of T. atroviride WT in improving root branching and biomass production decreased in all three related NADPH defective mutants, particularly in ΔnoxR. In contrast, induction of jasmonic acid-related defense responses in roots and shoots were exacerbated in ΔnoxR compared to the WT strain. Transcriptome analyses showed a tight plant-fungus communication based on reactive oxygen species and availability of carbon resources. The ΔnoxR is unable to perceive changes in nutrient sources and activate signaling cascades, which suppresses the metabolic change from saprophyte to commensal. Thus we conclude that Trichoderma NoxR orchestrates fungal-induced development and defense tradeoffs in Arabidopsis and plays an important role in cross-kingdom plant-fungus communication.
Project description:Trichoderma harzianum T34 is a fungal strain able to promote the plant growth and to increase plant defense responses. Trichoderma harzianum transformants expressing the amdS gene, encoding an acetamidase, of Aspergillus nidulans produce a higher plant development than the wild type T34. We used microarrays to analyze the physiological and biochemical changes in tomato plants produced as consequence of interaction with Trichoderma harzianum T34 and amdS transformants
Project description:Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant per-formance, growth and resistance/tolerance against abiotic and biotic stress. We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the gene expression pattern indicates a shift from defense to mutualistic interaction. We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the downregulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.
Project description:Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant per-formance, growth and resistance/tolerance against abiotic and biotic stress. We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the gene expression pattern indicates a shift from defense to mutualistic interaction. We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the downregulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance. Twelve day-old (48 h cold treatment and 10 days of illumination) Arabidopsis seedlings of equal sizes were selected for co-cultivation experiments. They were transferred to PNM plates with a nylone membrane on the top (Johnson et al. 2011) and exposed to a fungal plug 5 mm in diameter or a KM plug of the same size without fungal hyphae (control). The plugs were placed 3 cm away from the closest root part . The light intensity (80 ± 5 μmol m-2 sec-1) was checked every third day to ensure that both P. indica- and mock-treated seedlings receive equal amounts of light.
Project description:Asymptomatic plants grown in natural soil are colonized by phylogenetically structured communities of microbes known as the microbiota. Individual microbes can activate microbe-associated molecular pattern (MAMP)-triggered immunity (MTI), which limits pathogen proliferation but curtails plant growth, a phenomenon known as the growth-defense trade-off. We report that in mono-associations, 41% (62/151) of taxonomically diverse root bacteria commensals suppress Arabidopsis thaliana root growth inhibition (RGI) triggered by immune-stimulating MAMPs or damage-associated molecular patterns. Amplicon sequencing of bacteria 16S rRNA genes reveal that immune activation alters the profile of synthetic communities (SynComs) comprised of RGI-non-suppressive strains, while the presence of RGI-suppressive strains attenuates this effect. Root colonization by SynComs with different complexities and RGI-suppressive activities alters the expression of 174 core host genes with functions related to root development and nutrient transport. Further, RGI-suppressive SynComs specifically downregulate a subset of immune-related genes. Mutation of one commensal-downregulated transcription factor, MYB15, or pre-colonization with RGI-suppressive SynComs render plants more susceptible to opportunistic Pseudomonas pathogens. Our results suggest that RGI-non-suppressive and suppressive root commensals modulate host susceptibility to pathogens by either eliciting or dampening MTI responses, respectively. This interplay buffers the plant immune system against pathogen perturbation and defense-associated growth inhibition, ultimately leading to commensal-host homeostasis.
Project description:Asymptomatic plants grown in natural soil are colonized by phylogenetically structured communities of microbes known as the microbiota. Individual microbiota members can activate host innate immunity, which limits pathogen proliferation and curtails plant growth, a phenomenon known as the growth-defense trade-off. We report that in mono-associations, 41% (62/151) of taxonomically diverse root commensals suppress Arabidopsis root growth inhibition (RGI) triggered by immune-stimulating microbe-/damage-associated molecular patterns. 16S rRNA gene amplicon sequencing data reveal that immune activation alters the profile of synthetic communities (SynComs) comprised of RGI non-suppressive strains, while the presence of RGI-suppressive strains attenuates this effect. Chronic root transcriptional outputs in response to colonization with RGI-suppressive or non-suppressive SynComs share a core of genes with a stereotyped expression pattern. However, RGI-suppressive SynComs specifically downregulate a subset of immune-related genes. Such SynCom-specific modulation of defense is physiologically relevant as mutation of one commensal-downregulated transcription factor, MYB15, or pre-colonization with an RGI-suppressive SynCom render plants more susceptible to opportunistic Pseudomonas pathogens. Our results suggest that commensals with contrasting MTI modulating capacities interact with the plant host and together buffer the system against pathogen challenge, defense-associated plant growth inhibition and community shift via a crosstalk with the immune system, leading to commensal-host homeostasis.
Project description:The aim of our study is to elucidate the gene expression changes in rice in response to colonization by a plant growth promoting rhizobacteria such as the Bacillus subtilis through microarray high throughput technology. In particular, the effect of B.subtilis on root exudation (secretion of phytochemicals through roots) will be analysed. For this rice plantlets were grown in hydroponics and treated with B.subtilis RR4 for 48 hrs. The root samples of the control and treated plants were then used for the microarray experiment. The data obtained through microarray revealed genes related to cell wall modification, phytohormone synthesis, defense response, root exudation, etc. to be differentially regulated in response to B.subtilis RR4. Real time PCR analysis of few chosen genes (OsMS, OsALMT, OsABC, OsSDH, etc) also confirmed the validity of the microarray data. The initial responses of a plant in response to colonization by the microbe will be changes in cell wall of the plant tissues and the secretion of phytochemicals to attract/repel the colonizing beneficial/pathogenic organism. From analysis of microarray data we found the cell wall related genes which aid in root colonization and the root exudate related genes (biosynthesis and transport) which play a role in providing nutrition for the bacterial growth to be differentially regulated significantly. Analysis of specific genes and their biosynthesis pathways indicated that rice plants responded positively to root colonization by B.subtilis RR4. Notable among the exudation related genes such as Malate synthase and ALMT were found to be upregulated which indicates the significant role played by organic acids particularly malate in recruiting the PGPR towards the plant roots. This recruitment will thereby facilitate plant growth. Subsequently, these genes can be engineered in crop plants to recruit beneficial bacteria which might further open new avenues for improved crop production.