Multi-omics approach reveals the contribution of brassinosteroids to salt tolerance for seed germination in rice
Min Xiong, Chuxin Wang, Xinrui Liang, Jiawen Yu, Tingting Liu, Bin Peng, Xiaoxuan Du, Tingyu Yang, Gongneng Feng, Qiaoquan Liu, Qianfeng Li
Abstract
Brassinosteroid (BR) enhances the salt tolerance of rice seeds by improving their antioxidant capacity during germination. Five genes and two metabolites have been identified as key contributors to this process. OsDWF4 promotes the development and utilization of salt-tolerant rice germplasm. Seed germination, which initiates the plant life cycle, exhibits high sensitivity to salt stress, a significant environmental factor limiting rice production. Brassinosteroid (BR), a growth-promoting phytohormone, mitigates various stresses including salt, drought, and extreme temperatures in rice. However, the mechanisms by which BR alleviates salt stress during seed germination remain inadequately characterized. This study demonstrates that seed-specific overexpression of OsDWF4 , a rate-limiting gene in BR biosynthesis, enhances rice germination. The DWF4-OX lines, which increase endogenous BR content in seeds, promote germination under salt stress, corroborating results obtained through exogenous BR application. Antioxidant enzyme analyses demonstrate that BR enhances the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Metabolomic analysis reveals that BR mitigates salt stress primarily through the biosynthesis of phenylpropanoids and secondary metabolites. Transcriptomic analysis indicates that both endogenous and exogenous BR share five co-regulated target genes and utilize a common biosynthetic pathway for stilbenoids, diarylheptanoids, and gingerols. These findings confirm BR's capacity to enhance seed germination under salt stress and identify several BR-mediated targets for developing salt-tolerant rice varieties suitable for direct seeding cultivation.