Browsing by Author "Dixit, Sandeep Kumar"

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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, Muthappa
In 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.
Current understanding of regulation of GBF3 under abiotic and biotic stresses and its potential role in combined stress tolerance
(Taylor & Francis Group, 2019) Dixit, Sandeep Kumar; Gupta, Aarti; Senthil-Kumar, Muthappa
G-box binding factors (GBFs) belong to basic leucine zipper (bZIP) super family of transcription factors. Among six reported members of Arabidopsis thaliana GBFs, AtGBF3 transcripts has been shown to accumulate to high levels in dry seed, stamens, mature pollen and siliques. Amino acid sequence analysis of AtGBF3 reveals presence of proline rich region at N-terminus and basic leucine zipper domain at C-terminus. Earlier, it has been demonstrated that GBFs bind to the G-box element found within the promoter of stress responsive genes including alcohol dehydrogenase (AtAdh) and activate its transcription. Expression profile of AtGBF3 depicts increase in mRNA levels in plants under drought, osmotic, heat, salt and cold stress and biotic stresses. In silico analysis reveals GBF3 localization in nucleus and cytoplasm. Cues from localization studies on GBF3 homologs suggest that upon stress signal perception, GBF3 is phosphorylated and localized to nucleus where it can regulate expression of stress related genes. Till now target genes of GBF3 and mechanism of their regulation during individual and combined abiotic - biotic stresses is not comprehensively reviewed. Through our analysis in this review, we propose GBF3 as major player in integrating abscisic acid and salicylic acid cross talk during combined stress.