Deciphering ROS and ABA mediated WRKY transcription factors under abiotic stress conditions in Groundnut

Groundnut (Arachis hypogaea L.,), is an important subsistence oil yielding crop of the semi-arid tropics and often exposed to several environmental cues (high temperature, drought & heavy metal). The WRKY transcription factor (TF) is one of the master regulator, and play vital role in stress responses. However, far less information is available on functional characterization and tolerance mechanism of stress responsive WRKY genes in Groundnut till date. In this study, a comprehensive phylogenetic, protein features, gene structure and motif analysis of WRKY TF gene family was carried out. In addition, we conducted expression profiling of 10 WRKY genes under high temperature, drought and heavy metal (CdCl2). Majority of the AhWRKYs were clustered and share close relationship with Arabidopsis and Glycine max. RT-qPCR analysis of AhWRKY genes revealed that differential expression either in their transcript abundance or in their expression patterns in response to at least one abiotic stress. Of the 10 WRKY genes, AhWRKY41 level was found to be maximum in all the stress conditions. On other hand, AhWRKY20 and AhWRKY22 levels were decreased. The N-terminal of AhWRKY41 showed transcriptional activation in yeast cells. Higher levels of proline content and activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), but reduced malondialdehyde (MDA), and H2O2 levels were observed in all the stress conditions. The obtained data demonstrate that AhWRKY41 may act as a positive regulator in drought/ high temperature/heavy metal and would exhibit stress tolerance mechanism by activation of stress-associated gene expression by ABA mediated cellular antioxidant systems.