Grain size is an important component trait of grain yield, which is frequently threatened by abiotic stress. This research characterizes GSA1, a quantitative trait locus (QTL) regulating grain size and abiotic stress tolerance associated with metabolic flux redirection. GSA1 encodes a UDP-glucosyltransferase that regulates grain size by modulating cell proliferation and expansion via flavonoid-mediated auxin levels. Under abiotic stress, GSA1 redirects metabolic flux from lignin to flavonoid biosynthesis, leading to flavonoid glycoside accumulation and enhanced stress tolerance. GSA1 overexpression results in larger grains and improved stress tolerance.

Nai-Qian Dong, Yuwei Sun, Tao Guo, Chuan-Lin Shi, Yi-Min Zhang, Yi Kan, You-Huang Xiang, Hai Zhang, Yi-Bing Yang, Ya-Chao Li, Huai-Yu Zhao, Hong-Xiao Yu, Zi-Qi Lu, Yong Wang, Wang-Wei Ye, Jun-Xiang Shan, Hong-Xuan Lin