Project description:Combating the action of plant pathogenic microorganisms by antagonistic or mycoparasitic fungi has been announced as an attractive biological alternative to the use of chemical fungicides since more than 20 years, and gains additional importance in current trends to environmentally friendly agriculture. Taxa of the fungal genus Hypocrea/Trichoderma (Ascomycota, Hypocreales, Hypocreaceae) contain prominent examples of such biocontrol agents, because they not only antagonize plant-pathogenic fungi, but are also often rhizosphere competent and can enhance plant growth. Identification of the primary factors that regulate the mycoparasitic behaviour and metabolic activities related to it will therefore allow the full ecological significance of this trait to be explored. We performed the analysis of the genome sequence from two mycoparasitic and rhizosphere competent Trichoderma spp. – T. atroviride and T. virens – and compare it to that of the saprophyte T. reesei. The predicted gene inventory of the T. atroviride and T.virens genome, therefore, points to previously unknown mechanisms operating during biocontrol of plant pathogens. The availability of these genomes provides a unique opportunity to develop a deeper understanding of the processes fundamental to mycoparasitism and its application for the breeding of improved biocontrol strains for plant protection. To investigate the potential role in mycoparasitism, microarrays were used to examine T. virens transcript levels when confronted with a potential prey (the plant pathogen Rhizoctonia solani) before contact, during first physical contact and during overgrowth of the host. The study presented here is the result of this analysis.
Project description:Background: The biological control agent Pseudomonas chlororaphis PA23 is effective at protecting Brassica napus (canola) from the necrotrophic fungus Sclerotinia sclerotiorum via direct antagonism. Despite the growing importance of biocontrol bacteria in plant protection from fungal pathogens, little is known about how the host plant responds to bacterial priming on the leaf surface or about changes in gene activity genome-wide in the presence and absence of S. sclerotiorum. Results: PA23 priming of mature canola plants reduced the number of lesion forming petals by 90%. Global RNA sequencing of the host pathogen interface showed a reduction in the number of genes uniquely upregulated in response to S. sclerotiorum by 16-fold when pretreated with PA23. Upstream defense-related gene patterns suggest MAMP-triggered immunity via surface receptors detecting PA23 flagellin and peptidoglycans. Although systemic acquired resistance was induced in all treatment groups, a response centered around a glycerol-3-phosphate (G3P)-mediated pathway was exclusively observed in plants treated with PA23 alone. Activation of these defense mechanisms by PA23 involved mild reactive oxygen species production as well as pronounced thylakoid membrane structures and plastoglobule formation in leaf chloroplasts. Conclusion: Further to the direct antibiosis that it exhibits towards the pathogen S. sclerotiorum, PA23 primes defense responses in the plant through the induction of unique local and systemic defense regulatory networks. This study has shed light on the potential effects of biocontrol agents applied to the plant phyllosphere. Understanding these interactions will aid in the development of biocontrol systems as a viable alternative to chemical pesticides in the protection of important crop systems. Mature canola leaf tissue treated with combinations of PA23 or S. sclerotiorum ascospores (3 treatment groups) was compared to a water treated control (all treatments done in triplicate).
Project description:Combating the action of plant pathogenic microorganisms by antagonistic or mycoparasitic fungi has been announced as an attractive biological alternative to the use of chemical fungicides since more than 20 years, and gains additional importance in current trends to environmentally friendly agriculture. Taxa of the fungal genus Hypocrea/Trichoderma (Ascomycota, Hypocreales, Hypocreaceae) contain prominent examples of such biocontrol agents, because they not only antagonize plant-pathogenic fungi, but are also often rhizosphere competent and can enhance plant growth. Identification of the primary factors that regulate the mycoparasitic behaviour and metabolic activities related to it will therefore allow the full ecological significance of this trait to be explored. We performed the analysis of the genome sequence from two mycoparasitic and rhizosphere competent Trichoderma spp. – T. atroviride and T. virens – and compare it to that of the saprophyte T. reesei. The predicted gene inventory of the T. atroviride and T.virens genome, therefore, points to previously unknown mechanisms operating during biocontrol of plant pathogens. The availability of these genomes provides a unique opportunity to develop a deeper understanding of the processes fundamental to mycoparasitism and its application for the breeding of improved biocontrol strains for plant protection. To investigate the potential role in mycoparasitism, microarrays were used to examine T. virens transcript levels when confronted with a potential prey (the plant pathogen Rhizoctonia solani) before contact, during first physical contact and during overgrowth of the host. The study presented here is the result of this analysis. Two biological pools by condition against a common reference control each sample hybridized in dye switch. On the two biological replicates we apply on the pretreated results the linear modeling approach implemented by lmFit and the empirical Bayes statistics implemented by eBayes from the limma R package (Smyth 2004). For mycoparasitism confrontation assays T. virens was grown on potato dextrose agar plates (BD Dicfo, Franklin Lakes, NJ, USA), covered with cellophane, in constant light at 25°C and harvested when the mycelia were ca. 5 mm apart (before contact), at contact of the mycelia and after T. virens had overgrown the host fungus Rhizoctonia solani by ca. 5 mm (after contact). As control T. virens was confronted with itself and harvested at contact. Peripheral hyphal zones from each confrontation stage were harvested and shock frozen in liquid nitrogen. Mycelia were ground to a fine powder under liquid nitrogen and total RNA was isolated using the guanidinium thiocyanate method (Sambrook, 2001).
Project description:Plant can perceive and respond natural sound vibration (SV). Artificial SV also served as a novel trigger of induced resistance, although approaches for activating such plant innate immunity intensively studied on the use of biological and chemical agents (BCA). Artificial SV pre-treatment protected Arabidopsis thaliana seedlings against insect pests and fungal pathogens. However, SV-mediated epigenetic modulation remains unexplored while CBA-mediated induced resistance is known as a complicated process involving epigenetic regulation. Here, we performed a ChIP-seq analysis to understand the role of 10 kHz SV-mediated epigenetic modification in induced resistance against a soil-borne pathogenic bacterium Ralstonia solanacearum.
Project description:Background: The biological control agent Pseudomonas chlororaphis PA23 is effective at protecting Brassica napus (canola) from the necrotrophic fungus Sclerotinia sclerotiorum via direct antagonism. Despite the growing importance of biocontrol bacteria in plant protection from fungal pathogens, little is known about how the host plant responds to bacterial priming on the leaf surface or about changes in gene activity genome-wide in the presence and absence of S. sclerotiorum. Results: PA23 priming of mature canola plants reduced the number of lesion forming petals by 90%. Global RNA sequencing of the host pathogen interface showed a reduction in the number of genes uniquely upregulated in response to S. sclerotiorum by 16-fold when pretreated with PA23. Upstream defense-related gene patterns suggest MAMP-triggered immunity via surface receptors detecting PA23 flagellin and peptidoglycans. Although systemic acquired resistance was induced in all treatment groups, a response centered around a glycerol-3-phosphate (G3P)-mediated pathway was exclusively observed in plants treated with PA23 alone. Activation of these defense mechanisms by PA23 involved mild reactive oxygen species production as well as pronounced thylakoid membrane structures and plastoglobule formation in leaf chloroplasts. Conclusion: Further to the direct antibiosis that it exhibits towards the pathogen S. sclerotiorum, PA23 primes defense responses in the plant through the induction of unique local and systemic defense regulatory networks. This study has shed light on the potential effects of biocontrol agents applied to the plant phyllosphere. Understanding these interactions will aid in the development of biocontrol systems as a viable alternative to chemical pesticides in the protection of important crop systems.
Project description:Plant can perceive and respond natural sound vibration (SV). Artificial SV also served as a novel trigger of induced resistance, although approaches for activating such plant innate immunity intensively studied on the use of biological and chemical agents (BCA). Artificial SV pre-treatment protected Arabidopsis thaliana seedlings against insect pests and fungal pathogens. However, SV-mediated epigenetic modulation remains unexplored while CBA-mediated induced resistance is known as a complicated process involving epigenetic regulation. Here, we performed an expression profiling basd on small RNA-seq experiment to understand the role of 10 kHz SV-mediated epigenetic modification in induced resistance against a soil-borne pathogenic bacterium Ralstonia solanacearum.
Project description:Plant can perceive and respond natural sound vibration (SV). Artificial SV also served as a novel trigger of induced resistance, although approaches for activating such plant innate immunity intensively studied on the use of biological and chemical agents (BCA). Artificial SV pre-treatment protected Arabidopsis thaliana seedlings against insect pests and fungal pathogens. However, SV-mediated epigenetic modulation remains unexplored while CBA-mediated induced resistance is known as a complicated process involving epigenetic regulation. Here, we performed a gene expression profiling basd on RNA-seq experiment to understand the role of 10 kHz SV-mediated epigenetic modification in induced resistance against a soil-borne pathogenic bacterium Ralstonia solanacearum.
Project description:Extracellular vesicles (EVs) have been extensively studied in animal cells, and play an important role in cell-to-cell communications. Emerging evidence shows that EVs also act as important agents in plant-microbe interactions. However, the mechanisms by which EVs mediate cross-kingdom interactions between plants and microbial pathogens remain largely elusive. Here, proteomic analyses of soybean root rot pathogen Phytophthora sojae EVs identified tetraspanin family proteins, PsTET1 and PsTET3, that can be recognized by Nicotiana benthamiana to trigger plant immune responses. PsTET1 and PsTET3 were redundantly required for the full virulence of P. sojae. Further analyses revealed that the large extracellular loop (EC2) of PsTET3 is the key region recognized by N. benthamiana and also by Glycine max, and that recognition depends on the plant receptor-like kinase BAK1. TET proteins from oomycete and fungal plant pathogens could be recognized by N. benthamiana and induce immune responses. However, plant-derived TET proteins failed to do so, due to the divergent sequences of the final 16 amino acids of EC2, which ultimately makes plants distinguish self and non-self EVs, triggering active defenses against pathogenic eukaryotes.