State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
Plant Biotechnol J. 2023 Sep;21(9):1904-1918. doi: 10.1111/pbi.14102. Epub 2023 Jun 21.
Grain size is specified by three dimensions of length, width and thickness, and slender grain is a desirable quality trait in rice. Up to now, many grain size regulators have been identified. However, most of these molecules show influence on multi-dimensions of grain development, and only a few of them function specifically in grain width, a key factor determining grain yield and appearance quality. In this study, we identify the SLG2 (SLENDER GUY2) gene that specifically regulates grain width by affecting cell expansion in the spikelet hulls. SLG2 encodes a WD40 domain containing protein, and our biochemical analyses show that SLG2 acts as a transcription activator of its interacting WOX family protein WOX11. We demonstrate that the SLG2-associated WOX11 binds directly to the promoter of OsEXPB7, one of the downstream cell expansion genes. We show that knockout of WOX11 results in plants with a slender grain phenotype similar to the slg2 mutant. We also present that finer grains with different widths could be produced by combining SLG2 with the grain width regulator GW8. Collectively, we uncover the crucial role of SLG2 in grain width control, and provide a promising route to design rice plants with better grain shape and quality.
粒型由长度、宽度和厚度三个维度来确定，长粒是水稻的理想品质性状。到目前为止，已经鉴定出许多粒型调控因子。然而，这些分子大多数都对籽粒发育的多个维度有影响，只有少数几个分子特异作用于粒宽，粒宽是决定粒重和外观品质的关键因素。在这项研究中，我们鉴定了 SLG2（SLENDER GUY2）基因，该基因通过影响小穗颖壳中的细胞扩张来特异性调节粒宽。SLG2 编码一个含有 WD40 结构域的蛋白质，我们的生化分析表明，SLG2 作为其相互作用的 WOX 家族蛋白 WOX11 的转录激活因子发挥作用。我们证明，与 SLG2 相关的 WOX11 直接结合到下游细胞扩展基因 OsEXPB7 的启动子上。我们表明，WOX11 的敲除导致植物表现出与 slg2 突变体相似的细长粒表型。我们还表明，通过将 SLG2 与粒宽调控因子 GW8 结合，可以产生具有不同宽度的更细的粒。总的来说，我们揭示了 SLG2 在粒宽控制中的关键作用，并为设计具有更好粒形和品质的水稻植株提供了一条有前途的途径。
