Xiaoxing Zhang†, Wenjing Meng†, Dapu Liu†, Dezhuo Pan†, Yanzhao Yang, Zhuo Chen, Xiaoding Ma, Wenchao Yin, Mei Niu, Nana Dong, Jihong Liu, Weifeng Shen, Yuqin Liu, Zefu Lu, Chengcai Chu, Qian Qian*, Mingfu Zhao*, Hongning Tong*

Science； 2024； IF 56.9

DOI: 10.1126/science.adk8838

Abstract

Crop yield potential is constrained by the inherent trade-offs among traits such as between grain size and number. Brassinosteroids (BRs) promote grain size, yet their role in regulating grain number is unclear. By deciphering the clustered-spikelet rice germplasm, we show that activation of the BR catabolic gene BRASSINOSTEROID-DEFICIENT DWARF3 (BRD3) markedly increases grain number. We establish a molecular pathway in which the BR signaling inhibitor GSK3/SHAGGY-LIKE KINASE2 phosphorylates and stabilizes OsMADS1 transcriptional factor, which targets TERMINAL FLOWER1-like gene RICE CENTRORADIALIS2. The tissue-specific activation of BRD3 in the secondary branch meristems enhances panicle branching, minimizing negative effects on grain size, and improves grain yield. Our study showcases the power of tissue-specific hormonal manipulation in dismantling the trade-offs among various traits and thus unleashing crop yield potential in rice.