Improvement of Photosynthetic Performance by Acetic Acid to Enhance Drought Tolerance in Common Bean (Phaseolus vulgaris)

Common bean (Phaseolus vulgaris) is an essential crop. Unfortunately, it is hypersensitive to abiotic stresses, especially drought. Recently, chemical applications have proved to be a prominent approach for enhancing plant abiotic stress tolerance. Although acetic acid application has been reported to rescue plants from abiotic stresses, the function of acetic acid in drought responses in the common bean remains unclear. In this study, we investigated the effects of acetic acid on enhancing drought tolerance of common bean and their underlying phenotypic responses, and physiological and biochemical mechanisms. Our results showed a higher survival rate in acetic acid-pretreated than water-pretreated plants after the recovery from drought treatment. Acetic acid-pretreated plants exhibited greater chlorophyll, carotenoid and anthocyanin contents, higher relative water content, and a lower rate of electrolyte leakage compared with water-pretreated plants under drought. In comparison with water-pretreated plants, acetic acid-pretreated plants maintained higher photosynthetic performance as indicated by higher gas exchange and chlorophyll fluorescence parameters in responses to drought. A higher antioxidant capacity was shown in acetic acid-pretreated than water-pretreated plants, which helped plants detoxify drought-induced reactive oxygen species (ROS), thereby providing better adaptation to drought. Our results indicated that acetic acid pretreatment enhanced drought tolerance in common bean plants by increasing the photosynthetic performance and maintaining ROS homeostasis. This study will provide an avenue for agricultural applications using acetic acid pretreatment to mitigate drought stress in common bean and other crops.