Research Projects

The proposed study is based on the work reported previously on Arabidopsis wherein it was shown that exogenous application of ethanol can enhance salt stress tolerance by activation of ROS scavenging mechanisms that detoxify elevated ROS levels under stress (Nguyen et al., 2017). To gain deeper insight into the underlying molecular mechanism we initiated preliminary studies to examine if the cytosine Transfer RNA Aspartic Acid Methyltransferase 1 (TRDMT1/DNMT2) had a role in mediating ethanol induced stress response in these plants. The reason why we suspected TRDMT1/DNMT2 to be involved is because we had previously observed that loss-of-function mutants of TRDMT1/DNMT2 in Arabidopsis were highly sensitive to salt stress and they accumulated high levels of ROS due to mis regulation of the antioxidant proteins of the DETOX pathways (Wadhwa et al., 2023). So we used the previously characterized TRDMT1/DNMT2 mutant line and pre-treated the plants with 0.3% ethanol for 24 hours before exposing them to 150mM NaCl stress together with wild type plants. Weak response of mutant plants in lowering excess ROS and maintaining chlorophyll pigment levels in comparison to wild type plants suggested that ethanol-mediated salt stress tolerance could involve TRDMT1/DNMT2 regulated cellular processes/pathways (preliminary work, unpublished). To investigate the underlying regulatory mechanisms further, in the present project we propose to examine perturbations in the epigenome landscape using an experimental approach that integrates studies at epigenome, genome and transcriptome levels. In this direction, we will first examine the changes in histone modifications, focusing on the hallmarks of active and silent chromatin: H3K9me2, H3K27me3 and H3Ac in response to ethanol priming and salt stress using antibodies to detect these changes in crosslinked chromatin isolated wild type and trdmt1/dnmt2 plants. Next, to identify the hotspots of these modifications in the genomic regions, Chromatin Immunoprecipitation coupled with Next Generation Sequencing of the enriched chromatin bound DNA will be performed. Finally, to correlate the perturbations at epigenomic and genomic levels with fluctuations at transcript levels transcriptome profiling will be performed using total RNA extracted from wild type and trdmt1/dnmt2 plants post ethanol priming and stress exposure. Knowledge and information gained from this study will shed light on the stress tolerance strategies adopted by plants at molecular level and the significance of re-programming of epigenomic landscape in activating such responses when plants are primmed with ethanol and exposed to salt/osmotic stress. This can have wider applications in plant biology as the information on stress-responsive genes/pathways modulating the epigenomic patterns can be used as blueprint for initiating targeted manipulation for introgression of stress tolerance traits in crop plants of agronomic importance.