Deciphering the molecular mechanisms underlying abscisic acid-alleviated growth inhibition caused by perfluorooctane sulfonic acid in tomato plants.

Perfluorooctane sulfonic acid (PFOS) has been identified as a typical carcinogenic environmental organic pollutant. PFOS stress increases the abscisic acid (ABA) concentration in tomato plants; however, the molecular mechanisms underlying ABA-mediated PFOS stress responses in plants remain poorly understood. In this study, we demonstrated that exogenous ABA alleviates PFOS-mediated oxidative damage and growth inhibition in tomato plants. A comprehensive transcriptome analysis revealed that exogenous ABA induces the expression of genes involved in the responses to reactive oxygen species (ROS) and water deprivation, thereby reducing ROS accumulation and increasing water content in tomato plants under PFOS stress. Furthermore, using transcriptional regulatory network analysis, we revealed that SlMYB75 and SlMYC2 are potentially involved in ABA-mediated PFOS stress tolerance in tomato. SlMYB75-overexpressing (SlMYB75OX) plants exhibit decreased oxidative damage under PFOS stress by improving antioxidative enzyme activities, whereas the gene-edited slmyc2 mutants exhibit the opposite phenotype, indicating that SlMYB75 and SlMYC2 function as positive regulators of PFOS stress tolerance. Taken together, these results indicated that PFOS-induced ABA accumulation improved PFOS stress adaptation by increasing the expression of genes involved in phytohormone pathways and the responses to ROS in tomato plants.