Involvement of WRKY62/63 transcription factors in OGs-induced cellular redox homeostasis and antioxidant defense in Arabidopsis thaliana.

BACKGROUND

Reactive oxygen species (ROS) are key signaling molecules in plant responses against biotic stresses, however their regulation must be controlled to prevent cellular damage. WRKY transcription factors (TFs) play role in regulating biotic stresses via oxidative stress-related signaling molecules; however, specific functions of WRKY62 and WRKY63 in oxidative stress signaling remain poorly understood. The paper aims to investigate the physiological and molecular function of WRKY62 and WRKY63 TFs in Arabidopsis thaliana under biotic stress induced by oligogalacturonides (OGs).

MATERIALS AND

METHODS

In this study, photosynthetic performance, ROS accumulation, activities of antioxidants and selected defense-associated transcriptional responses were evaluated in wrky62 and wrky 63 mutants along with wild-type (WT) plants of A. thaliana following OGs treatment.

RESULTS

In silico studies depicted conserved WRKYGQK motif; while phylogenetic analysis formed two clades of WRKY TFs with orthologs. Promoter analysis showed that they contain environment-related, hormone-related and light-responsive elements. Treatment of 200 μM OGs to WT and wrky mutant plants increased proline, ROS, malondialdehyde accumulation, and increased activities of enzymatic and non-enzymatic antioxidants, with lesser increase in wrky mutants. These results support with their predicted regulatory roles in stress signaling. Furthermore, expression analysis showed upregulation of wall-associated kinase 1 and respiratory burst oxidase homolog D genes in WT plants compared to wrky mutants.

CONCLUSION

These findings suggest that WRKY62 and WRKY63 are strongly associated with OGs-induced redox homeostasis and antioxidant responses under the tested experimental conditions and could serve as possible targets for enhancing stress tolerance in plants.