Publications of NIPGR Scientists
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Item AtGBF3 confers tolerance to Arabidopsis thaliana against combined drought and Pseudomonas syringae stress(Elsevier B.V., 2019) Dixit, Sandeep Kumar; Gupta, Aarti; Fatima, Urooj; Senthil-Kumar, MuthappaIn field conditions, plants are often exposed to a combination of abiotic and biotic stresses, for instance, drought and pathogen infection. Transcriptome studies on Arabidopsis thaliana and other plants under individual and combined drought and pathogen stresses have unveiled the activation of shared molecular defense mechanisms. These shared plant responses are characterized by commonly regulated genes under both individual as well as combined stresses. Therefore, the identification of commonly regulated genes during individual and combined stress conditions can reveal plant responses towards combined stress. Available transcriptome studies on combined-stressed plants have hinted at G-Box Binding Factor 3 (GBF3) as one of the regulatory components of the shared response. However, the mechanistic understanding of the role of AtGBF3 under combined drought and pathogen stress is not yet decoded. In the current study, we used genetic approaches to identify the role of AtGBF3 in conferring tolerance to individual and combined drought and pathogen stress. Atgbf3 mutant plants showed increased susceptibility, while AtGBF3-overexpressing plants were tolerant under individual and combined drought and Pseudomonas syringae pv. tomato infection stresses as compared to wild-type plants. We further analyzed the global transcriptome of Atgbf3 mutant plants under combined stress to identify its downstream targets. We also established a high-throughput method to apply combined polyethylene glycol and pathogen stress on Murashige and Skoog medium-grown plants to further validate the role of AtGBF3 in combined stress.Item Concurrent drought stress and vascular pathogen infection induce common and distinct transcriptomic responses in chickpea(Frontiers Media S.A., 2017) Sinha, Ranjita; Gupta, Aarti; Senthil-Kumar, MuthappaChickpea (Cicer arietinum); the second largest legume grown worldwide is prone to drought and various pathogen infections. These drought and pathogen stresses often occur concurrently in the field conditions. However, the molecular events in response to that are largely unknown. The present study examines the transcriptome dynamics in chickpea plants exposed to a combination of water-deficit stress and Ralstonia solanacearum infection. R. solanacearum is a potential wilt disease causing pathogen in chickpea. Drought stressed chickpea plants were infected with this pathogen and the plants were allowed to experience progressive drought with 2 and 4 days of R. solanacearum infection called short duration stress (SD stresses) and long duration stress (LD stresses), respectively. Our study showed that R. solanacearum multiplication decreased under SD-combined stress compared to SD-pathogen but there was no significant change in LD-combined stress compared to LD-pathogen. The microarray analysis during these conditions showed that 821 and 1039 differentially expressed genes (DEGs) were unique to SD- and LD-combined stresses, respectively, when compared with individual stress conditions. Three and fifteen genes were common among all the SD-stress treatments and LD-stress treatments, respectively. Genes involved in secondary cell wall biosynthesis, alkaloid biosynthesis, defense related proteins, and osmo-protectants were up-regulated during combined stress. The expression of genes involved in lignin and cellulose biosynthesis were specifically up-regulated in SD-combined, LD-combined, and LD-pathogen stress. A close transcriptomic association of LD-pathogen stress with SD-combined stress was observed in this study which indicates that R. solanacearum infection also exerts drought stress along with pathogen stress thus mimics combined stress effect. Furthermore the expression profiling of candidate genes using real-time quantitative PCR validated the microarray data. The study showed that down-regulation of defense-related genes during LD-combined stress resulted in an increased bacterial multiplication as compared to SD-combined stress. Overall, our study highlights a sub-set of DEGs uniquely expressed in response to combined stress, which serve as potential candidates for further functional characterization to delineate the molecular response of the plant to concurrent drought-pathogen stress.
