Ang Yang, Li Bingxian, Shen Jiaming, Li Jiahui, Zhao Yingying, Li Tianhu, Sun Hao, Cheng Xianping, Wu Fengcai, Du Mingyu, Zhang Chaopu, Shi Yingyao, Li Min, Liu Erbao
College of Agronomy, Anhui Agricultural University, Hefei, 230036, China.
Plant J. 2025 Jun;122(5):e70247. doi: 10.1111/tpj.70247.
Rice grain size is an important agronomic trait that affects the grain weight and yield of rice (Oryza sativa). In this study, genome-wide association studies (GWASs) were performed regarding grain length (GL), grain width (GW), grain thickness (GT), the grain length-width ratio (GLWR) and the 1000-grain weight (TGW) across 172 rice accessions in 2020, 2021 and 2022. Among the 31 QTLs identified across all 3 years, the QTL qGL8/qGW8/qGT8/qGLWR8 on chromosome 8 was newly discovered in our study. OsFBX291 was validated as the key candidate gene for GRAIN SIZE8 (GS8) through CRISPR/Cas9-mediated knockout analysis. GS8 encodes a nucleus-localized protein containing an F-box domain that is constitutively expressed across multiple tissues. The A7444 allele (GS8) promotes cell proliferation and expansion in grain glumes by increasing the CTK and GA contents in young panicles. Moreover, RNA sequencing analysis revealed that GS8 regulates the expression of GA and CTK signalling pathway-related genes, such as GL10, OsGA20ox1, OsGA20ox2, OsCKX1 and WLG, which participate in the regulation of cell proliferation and hull expansion. Multiple sets of experimental data have collectively demonstrated that GS8 and GL10 exhibit protein-protein interaction. These findings suggest that the GS8-GL10 functional module plays a regulatory role in determining rice grain size by modulating the expression of genes associated with gibberellin (GA)- and cytokinin (CTK)-signaling pathways. The elite GS8 haplotype has a large grain size in the germplasm. These results provide important genetic information that can be used to further improve grain size through molecular breeding.
米粒大小是影响水稻（Oryza sativa）粒重和产量的重要农艺性状。在本研究中，于2020年、2021年和2022年对172份水稻种质的粒长（GL）、粒宽（GW）、粒厚（GT）、粒长宽比（GLWR）和千粒重（TGW）进行了全基因组关联研究（GWAS）。在这三年中鉴定出的31个数量性状基因座（QTL）中，我们的研究新发现了位于第8号染色体上的QTL qGL8/qGW8/qGT8/qGLWR8。通过CRISPR/Cas9介导的敲除分析，验证了OsFBX291是粒型8（GS8）的关键候选基因。GS8编码一种定位于细胞核的蛋白质，含有一个F-box结构域，在多个组织中组成型表达。A7444等位基因（GS8）通过增加幼穗中的细胞分裂素（CTK）和赤霉素（GA）含量，促进颖壳细胞的增殖和扩展。此外，RNA测序分析表明，GS8调节GA和CTK信号通路相关基因的表达，如GL10、OsGA20ox1、OsGA20ox2、OsCKX1和WLG，这些基因参与细胞增殖和颖壳扩展的调控。多组实验数据共同表明，GS8和GL10存在蛋白质-蛋白质相互作用。这些发现表明，GS8-GL10功能模块通过调节与赤霉素（GA）和细胞分裂素（CTK）信号通路相关基因的表达，在决定水稻粒型方面发挥调控作用。优良的GS8单倍型在种质中具有较大的粒型。这些结果提供了重要的遗传信息，可用于通过分子育种进一步改善粒型。
