Inoculation of Trichoderma asperelloides NT33 causes minor transcriptional changes in tomato plants under water deficit stress conditions.

Abstract

Abstract The growth-promoting fungi Trichoderma are reported to have a positive effect on the morphological and physio-chemical properties of plants under water deficit stress conditions. In the present study, transcriptomic analysis was conducted to understand the key molecular mechanisms and candidate genes involved in water deficit response in drought susceptible tomato genotype 'Jaune Flamme' when colonized by Trichoderma asperelloides NT33. The data showed that gene expression differences between irrigation treatments were more pronounced than those due to Trichoderma inoculation. Specifically, we found that more than 16,000 genes were differentially expressed between water deficit stress and irrigated plants, while only 28 genes were differentially expressed between NT33 inoculated and non-inoculated treatments under water stress conditions. Nevertheless, nine of these 28 genes have important roles in stress tolerance mechanisms. The transcriptomic study showed that the metabolic pathways involved in secondary metabolite production are one of the main mechanisms adopted by NT33 inoculated plants for maintenance of homeostasis balance under water deficit stress conditions compared to non-inoculated control plants. Among genes upregulated in inoculated (versus non-inoculated) plants under water deficit stress conditions, gene ontology categories involved in regulation of secondary metabolite biosynthetic processes, anthocyanin biosynthetic processes, phospholipase activity, cellular responses to stress, lipid catabolic processes, and regulation of stomata development were overrepresented. On the other hand, genes downregulated in NT33 inoculated samples were involved in the induction of defense response and signaling such as pathogenesis-related proteins, polyphenol oxidase, and chitinase, compared to non-inoculated control samples under water deficit stress. Overall, this study identified key molecular mechanisms involved in water deficit tolerance in the drought susceptible tomato, 'Jaune Flamme', using a novel Trichoderma asperelloides NT33.