Yuan Hua, Xu Zhengyan, Chen Weilan, Deng Chaoyang, Liu Yi, Yuan Min, Gao Peng, Shi Hui, Tu Bin, Li Ting, Kang Liangzhu, Ma Bingtian, Wang Yuping, Wang Jing, Chen Xuewei, Li Shigui, Qin Peng
State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Chengdu, Sichuan, China.
Rice Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, China.
J Exp Bot. 2022 Sep 12;73(16):5529-5542. doi: 10.1093/jxb/erac222.
Grain size is an important trait that directly affects grain yield in rice; however, the genetic and molecular mechanisms regulating grain size remain unclear. In this study, we identified a mutant, grain length and grain weight 10 (glw10), which exhibited significantly reduced grain length and grain weight. Histological analysis demonstrated that GLW10 affects cell expansion, which regulates grain size. MutMap-based gene mapping and transgenic experiments demonstrated that GLW10 encodes a putative brassinosteroid (BR) signalling kinase, OsBSK2. OsBSK2 is a plasma membrane protein, and an N-myristoylation site is needed for both membrane localization and function. OsBSK2 directly interacts with the BR receptor kinase OsBRI1; however, genetic experiments have demonstrated that OsBSK2 may regulate grain size independent of the BR signalling pathway. OsBSK2 can form a homodimer or heterodimer with OsBSK3 and OsBSK4, and silencing OsBSK2, OsBSK3, and OsBSK4 reduce grain size. This indicates that OsBSKs seem to function as homodimers or heterodimers to positively regulate grain size in rice. OsBSK2/3/4 are all highly expressed in young panicles and spikelet hulls, suggesting that they control grain size. In summary, our results provide novel insights into the function of BSKs in rice, and identify novel targets for improving grain size during crop breeding.
粒长是直接影响水稻产量的重要性状；然而，调控粒长的遗传和分子机制仍不清楚。在本研究中，我们鉴定出一个突变体，粒长和粒重10（glw10），其粒长和粒重显著降低。组织学分析表明，GLW10影响细胞扩张，从而调控粒长。基于MutMap的基因定位和转基因实验表明，GLW10编码一个假定的油菜素内酯（BR）信号激酶，OsBSK2。OsBSK2是一种质膜蛋白，膜定位和功能都需要一个N-肉豆蔻酰化位点。OsBSK2直接与BR受体激酶OsBRI1相互作用；然而，遗传实验表明，OsBSK2可能独立于BR信号通路调控粒长。OsBSK2可以与OsBSK3和OsBSK4形成同二聚体或异二聚体，沉默OsBSK2、OsBSK3和OsBSK4会减小粒长。这表明OsBSK似乎作为同二聚体或异二聚体发挥作用，正向调控水稻粒长。OsBSK2/3/4在幼穗和颖壳中均高度表达，表示它们控制粒长。总之，我们的结果为水稻中BSK的功能提供了新见解，并为作物育种过程中改善粒长鉴定了新靶点。
