Enhanced drought tolerance in tomato plants by overexpression of SlMAPK1

Drought stress is one of the most destructive environmental factors that affect plant growth and agricultural production. Mitogen-activated protein kinase (MAPK) cascades are important signaling pathways that participate in both biotic and abiotic stresses, which include drought. In this study, SlMAPK1 was induced by various abiotic stresses and hormone treatments. Transgenic tomato plants overexpressing SlMAPK1 were generated to further investigate the role that SlMAPK1 plays in drought tolerance. Three independent T2 transgenic lines and wild-type (WT) tomato plants were used for analysis of drought tolerance. Compared with WT plants, SlMAPK1-overexpressing lines exhibited less severe wilting, less severe cell membrane damage, and higher soluble protein and soluble sugar content, accumulated less hydrogen peroxide (H2O2), showed higher activities in the antioxidant enzymes including ascorbate peroxidase, catalase, peroxidase, and superoxide dismutase, and had an elevated transcript level of stress-related genes. Taken together, the results suggest that SlMAPK1 plays a positive role in response to drought stress by activating antioxidant enzymes, reducing oxidative damage, and modulating transcription of stress-related genes.