Overexpression of the OsFes1A increased the phytosterols content and enhanced drought and salt stress tolerance in Arabidopsis

Main conclusion Overexpression of the rice gene, OsFes1A , increased phytosterol content and drought and salt stress tolerance in Arabidopsis . Abstract Phytosterols are key components of the phospholipid bilayer membrane and regulate various processes of plant growth and response to biotic and abiotic stresses. In this study, it was demonstrated that the overexpression of OsFes1A (Hsp70 nucleotide exchange factor Fes1) increased phytosterols content and enhanced tolerance to salt and drought stress in Arabidopsis . In transgenic plants, the average content of campesterol was 17.6% higher than that of WT, and the average content of β-sitosterol reached 923.75 μg/g, with an increase of 1.33-fold. In fes1a seeds, the contents of campesterol and β-sitosterol reduced by 20% and 10.93%, respectively. In OsFes1A transgenic seeds, the contents of campesterol and β-sitosterol increased by 1.38-fold and 1.25-fold respectively. Furthermore, the germination rate of transgenic Arabidopsis was significantly higher than WT under stress (salt, ABA, and drought treatment). Under salt stress, transgenic plants accumulated a lower MDA content, higher chlorophyll content, and POD activity relative to the wild type, while the mutants showed the opposite pattern Our study found multiple other functions of OsFes1A beyond the defined role of Fes1 in regulating Hsp70, contributing to the better understanding of the essential roles of Fes1 in plants. Meanwhile, it provides the theoretical basis for developing high phytosterol crop varieties.