Volatile compounds emitted by Plant Growth Promoting Fungi Tolypocladium inflatum GT22 alleviates copper and pathogen stress
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ABSTRACT: The intricate interactions between plants and microorganisms have garnered substantial scientific interest. While previous studies have highlighted the potential influence of various fungal volatile compounds(VCs) on plant growth and development, the precise mechanisms underlying this modulation still need to be discovered. In this study, we discovered that fungal volatile organic compounds from the soil-borne fungus Tolypocladium inflatum GT22 enhance the growth of Arabidopsis. Remarkably, following the priming of Arabidopsis with GT22 VC, it displayed an enhanced immune response, thereby mitigating the detrimental effects caused by both pathogenic infections and copper stress. Transcriptomic analyses of Arabidopsis seedlings treated with GT22 VCs revealed the differential expression of 90, 83, and 137 genes after 3, 24, and 48 hours of volatile exposure, respectively. These responsive genes are involved in growth, hormone regulation, defense mechanisms, and signaling pathways. Notably, the induction of genes related to innate immunity, hypoxia, salicylic acid (SA) biosynthesis and camalexin biosynthesis by GT22 VCs were reported. Among the VCs emitted by GT22, limonene is particularly noteworthy. Arabidopsis seedlings exposed to limonene exhibited not only growth promotion effects but also alleviation of copper stress, indicating that limonene may play a role in the interaction between GT22 and plants. Overall, the findings of this study provide evidence supporting that fungal VCs can promote plant growth and enhance both biotic and abiotic tolerance. Furthermore, our results suggest that seedlings exposed to T. inflatum GT22 VCs holds promising potential for harnessing beneficial effects to improve crop productivity.
Project description:The oomycete Pythium oligandrum is a potential biocontrol agent to control a wide range of fungal and oomycetes-caused diseases such as Pythium myriotylum-caused rhizome rot in ginger leading to reduced yields and compromised quality. Previously, P. oligandrum has been studied for its plant growth-promoting potential by auxin production and induction of disease resistance by elicitors such as oligandrin. Volatile organic compounds (VOCs) play beneficial roles in sustainable agriculture by enhancing plant growth and resistance. We investigated the contribution of P. oligandrum-produced VOCs on plant growth and disease suppression by initially using N. benthamiana plants for screening. P. oligandrum VOCs significantly enhanced tobacco seedling and plant biomass content. Screening of the individual VOCs showed that 3-octanone and hexadecane promoted the growth of tobacco seedlings. The total VOCs from P. oligandrum also enhanced the shoot and root growth of ginger plants. Transcriptomic analysis showed a higher expression of genes related to plant growth hormones, and stress responses in the leaves of ginger plants exposed to P. oligandrum VOCs. The concentrations of plant growth hormones such as auxin, zeatin, and gibberellic acid were higher in the leaves of ginger plants exposed to P. oligandrum VOCs. In a ginger disease biocontrol assay, the VOC-exposed ginger plants infected with P. myriotylum had lower levels of disease severity. We conclude that this study contributes to understanding the growth-promoting mechanisms of P. oligandrum on ginger and tobacco, priming of ginger plants against various stress and the mechanisms of action of P. oligandrum as a biocontrol agent.
Project description:When aboveground parts of intact plants are exposed to volatile organic compounds emitted from neighboring con-/heterospecific plants that are artificially damaged or damaged by herbivores, the resistant responses are induced in the plants. Differential responses of plants to enantiomers of the same volatile compound have also been reported in Arabidopsis: the root became shorter when Arabidopsis seedlings are exposed to aerial borneol, and the dose-dependent root length reduction was significantly different between (+)- and (-)-borneol. We identified (+)-borneol dependent inductive genes in Arabidpsis in this transcriptome analysis.
Project description:Transcriptional profiling of Arabidopsis thaliana seedlings treated with safranal, highlighting to the physiological function of plant volatile chemicals by observing early response of gene expressions in Arabidopsis seedlings.
Project description:Transcriptional profiling of Arabidopsis thaliana seedlings treated with trans-2-hexenal, highlighting to the physiological function of plant volatile chemicals by observing early response of gene expressions in Arabidopsis seedlings.
Project description:Increasing evidence suggests that in disease-suppressive soils, microbial volatile compounds (mVCs) released from bacteria may inhibit the growth of plant-pathogenic fungi. However, the antifungal activities and molecular responses of fungi to different mVCs remain largely undescribed. In this study, we first evaluated the responses of pathogenic fungi to treatment with mVCs from Paenarthrobacter ureafaciens. Then, we utilized the well-characterized fungal model organism Saccharomyces cerevisiae to study the potential mechanistic effects of the mVCs. Our data showed that exposure to P. ureafaciens mVCs leads to reduced growth of several pathogenic fungi, and in yeast cells, mVC exposure prompts the accumulation of reactive oxygen species (ROS). Further experiments with S. cerevisiae deletion mutants indicated that Slt2/Mpk1 and Hog1 MAPKs play major roles in the yeast response to P. ureafaciens mVCs. Transcriptomic analysis revealed that exposure to mVCs was associated with 1030 differentially expressed genes (DEGs) in the yeast. According to GO and KEGG analyses, many of these DEGs are involved in mitochondrial dysfunction, cell integrity, mitophagy, cellular metabolism and iron uptake. Genes encoding antimicrobial proteins were also significantly altered in the yeast after exposure to mVCs. These findings suggest that oxidative damage and mitochondrial dysfunction are major contributors to the fungal toxicity of mVCs. Furthermore, our data showed that cell wall defenses, antioxidant defenses and antimicrobial defenses are induced in yeast exposed to mVCs. Thus, our findings expand upon previous research by delineating the transcriptional responses of fungal model.
Project description:Terpene volatiles play an important role in the interactions among specialized pathogens and fruits. Citrus Black Spot (CBS), caused by the fungus Phyllosticta citricarpa, is associated with losses in different citrus-growing areas worldwide. The pathogen may infect the fruit for 20-24 weeks after petal fall but the typical hard spot symptoms appear when the fruit become almost mature, as consequence of fungal colonization and induction of cell lyses around essential oil cavities. D-limonene represents about 95% of total oil gland content in mature orange fruit. We have used here d-limonene synthase downregulated orange fruit generated via an antisense (AS) approach to investigate whether d-limonene decrease content in peel oil glands may affect fruit interaction with P. citricarpa compared to that of empty-vector (EV) controls. AS fruit showed enhanced resistance to the fungus compared to EV ones. Because of d-limonene decreased content, an over-accumulation of linalool and other monoterpene alcohols was found in AS compared to EV fruit. A global gene expression analysis at 2h and 8d after inoculation with P. citricarpa revealed activation of defence responses in AS fruit, via the upregulation of different PR genes, likely due to the enhanced constitutive accumulation of linalool and other alcohols. When assayed in vitro and in vivo, the main altered terpene volatile compounds including linalool at concentrations emulating those present in AS fruit, showed strong antifungal activity. We show here that terpene engineering in fruit peels could be a promising method for developing new strategies to obtain resistance to fruit diseases.
Project description:Transcriptional profiling of Arabidopsis thaliana seedlings treated with safranal, highlighting to the physiological function of plant volatile chemicals by observing early response of gene expressions in Arabidopsis seedlings. Two-condition experiment, safranal-treated seedlings vs. control seedlings. Biological replicates:2 control replicates, 2 safranal-treated.