The cytochrome P450 protein AtCYP85A2 increases stresses tolerance through promoting brassinosteroid biosynthesis in...

The cytochrome P450 (CYP) gene family plays crucial roles in plant growth and development under various conditions through controlling brassinosteroid (BR) biosynthesis, but its functions in fruit crops remain largely unexplored. Here, the Arabidopsis AtCYP85A2 gene, which encodes a BR synthase and belongs to the P450 gene family, was heterologously expressed in tomato to analyse its function in stress response. Constitutive expression of AtCYP85A2 in tomato elevated endogenous BR levels; the expression of AtCYP85A2 increased the content of BL, resulting in a 119.8 % increase compared to the WT, which promoted the growth and improved the salt and drought tolerance of transgenic tomato. Under salt and drought stress conditions, transgenic plants exhibited less phenotypic damage. Compared to the wild type, the fresh weight and dry weight of transgenic plants increased by 38.3 % and 77.8 % in salt stress, and 141.7 % and 146.2 % in drought stress, respectively. Chlorophyll content increased by 93.1 % and 262.5 %, respectively. Furthermore, transgenic plants showed enhanced antioxidant enzymatic activity and increased expression of antioxidant enzyme-encoding genes under these stress conditions. Specifically, SOD, CAT, and APX activities increased by 237.1 %, 66.2 %, and 168.8 % under salt stress, and by 234.3 %, 68.8 %, and 108.2 % under drought stress, respectively. Collectively, these findings indicated that AtCYP85A2 positively regulates salt and drought tolerance in tomato via the modulation of ion homeostasis and reactive oxygen species (ROS) metabolism, highlighting its potential as a target gene for enhancing stress tolerance in fruit crops.