Comparative Study of Cis- and Trans-Priming Effect of PEG and BABA in Cowpea Seedlings on Exposure to PEG-Induced Osmotic Stress

The growth and performance of cowpea seedlings are negatively impacted by climate change and the subsequent occurrence of drought stress. Osmotic stress leads to the formation of reactive oxygen species, causing membrane breakdown, and impairs metabolic activities. The harmful effects of osmotic stress can be reduced by using seed priming techniques. Seeds of cowpea var. Anaswara were treated with polyethylene glycol (PEG) and β-amino butyric acid (BABA) as priming agents. The seedlings emerged from the primed seeds have been found to reduce the lipid peroxidation rates and improve plant water status by accumulating osmolytes such as proline, total free aminoacids, and total soluble sugars, and also enhanced the production of non-enzymatic antioxidants such as total phenolics, ascorbate, and glutathione, as well as increased the activities of enzymatic antioxidants such as catalase, peroxidase, and superoxide dismutase, which effectively scavenge ROS and maintain the homeostasis of the cell. PEG priming (cis-priming) and BABA priming (trans-priming) exhibited differential physiochemical responses in cowpea subjected to PEG stress. The current work investigates the extent of stress tolerance acquired through seed priming, and it will help to make a sensitive variety to a more tolerant one. Physiochemical responses of seedlings emerged from BABA-primed seeds towards PEG stress were better regulated to encounter the PEG-induced osmotic stress than the seedlings emerged from PEG-primed seeds.