State Key Laboratory of Plant Cell and Chromosome Engineering, CAS Centre for Excellence in Molecular Plant Biology, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
Plant Cell. 2020 Jun;32(6):1905-1918. doi: 10.1105/tpc.19.00468. Epub 2020 Apr 17.
Regulation of grain size is crucial for improving crop yield and is also a basic aspect in developmental biology. However, the genetic and molecular mechanisms underlying grain size control in crops remain largely unknown despite their central importance. Here, we report that the MEI2-LIKE PROTEIN4 (OML4) encoded by the gene is phosphorylated by GLYCOGEN SYNTHASE KINASE2 (GSK2) and negatively controls grain size and weight in rice (). Loss of function of leads to large and heavy grains, while overexpression of causes small and light grains. OML4 regulates grain size by restricting cell expansion in the spikelet hull. is expressed in developing panicles and grains, and the GFP-OML4 fusion protein is localized in the nuclei. Biochemical analyses show that the GSK2 physically interacts with OML4 and phosphorylates it, thereby possibly influencing the stability of OML4. Genetic analyses support that GSK2 and OML4 act, at least in part, in a common pathway to control grain size in rice. These results reveal the genetic and molecular mechanism of a GSK2-OML4 regulatory module in grain size control, suggesting that this pathway is a suitable target for improving seed size and weight in crops.
调控粒宽对于提高作物产量至关重要，也是发育生物学的基本方面。然而，尽管其重要性不言而喻，但控制作物粒宽的遗传和分子机制在很大程度上仍不清楚。在这里，我们报道由基因编码的类 MEI2 蛋白 4（OML4）被糖原合成酶激酶 2（GSK2）磷酸化，负调控水稻的粒宽和粒重（）。缺失功能导致粒大且重，而过表达则导致粒小且轻。OML4 通过限制小穗外壳细胞的扩张来调节粒宽。在发育中的穗和籽粒中表达，GFP-OML4 融合蛋白定位于细胞核中。生化分析表明，GSK2 与 OML4 发生物理相互作用并对其进行磷酸化，从而可能影响 OML4 的稳定性。遗传分析支持 GSK2 和 OML4 至少部分在共同途径中起作用，以控制水稻的粒宽。这些结果揭示了 GSK2-OML4 调控模块在粒宽控制中的遗传和分子机制，表明该途径是提高作物种子大小和重量的合适靶点。
