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R2R3 MYB transcription factors are involved in plant growth and development and abiotic and biotic stress responses. Several MYB genes are involved in salt tolerance in several plant species. In this study, salt-tolerant groundnut cultivar K-9's stress-responsive transcription factor AhMYB94 was overexpressed in salt-susceptible groundnut cultivar K-6. The AhMYB94 gene was activated under drought and salinity. Relative gene expression analysis revealed that AhMYB94 was significantly higher by salt stress treatments than drought stress in groundnut cultivar K-6. Overexpression of AhMYB94 in a salt susceptible groundnut cultivar improved the salt tolerance as evidenced by better growth status, fresh and dry biomass of overexpression lines than wild type (WT) under salt stress conditions. Further, less reactive oxygen species (ROS) accumulated in AhMYB94 overexpressing lines when exposed to salt stress, as estimated by diaminobenzidine (DAB) or nitroblue tetrazolium (NBT) histochemical staining. Further overexpression of AhMYB94 in groundnut confers significantly increased tolerance ability of plants to oxidative damage under salt stress, mainly by increasing the osmolyte content, the activities of antioxidative enzymes such as SOD, and APX, reducing malonaldehyde (MDA) content, and upregulation of the expression of stress-related genes. When exposed to salt stress, the AhMYB94 transgenic lines demonstrated a higher Na + and K + content and a lower Na + /K + ratio than the wild type (WT). These results demonstrated that AhMYB94 plays a positive role in enhancing salt tolerance and could be a candidate for improved tolerance of plants to salt stress. |
