Institute of Crop Sciences, the Chinese Academy of Agriculture Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Beijing, 100081, China.
Key Laboratory of Crop Genetics and Germplasm Enhancement/Jiangsu Provincial Center of Plant Gene Engineering, Nanjing Agricultural University, Nanjing, 210095, China.
J Integr Plant Biol. 2019 Nov;61(11):1171-1185. doi: 10.1111/jipb.12745. Epub 2019 Feb 1.
Grain size is an important determinant of yield potential in crops. We previously demonstrated that natural mutations in the regulatory sequences of qSW5/GW5 confer grain width diversity in rice. However, the biological function of a GW5 homolog, named GW5-Like (GW5L), remains unknown. In this study, we report on GW5L knockout mutants in Kitaake, a japonica cultivar (cv.) considered to have a weak gw5 variant allele that confers shorter and wider grains. GW5L is evenly expressed in various tissues, and its protein product is localized to the plasma membrane. Biochemical assays verified that GW5L functions in a similar fashion to GW5. It positively regulates brassinosteroid (BR) signaling through repression of the phosphorylation activity of GSK2. Genetic data show that GW5L overexpression in either Kitaake or a GW5 knockout line, Kasa (indica cv. Kasalath background), causes more slender, longer grains relative to the wild-type. We also show that GW5L could confer salt stress resistance through an association with calmodulin protein OsCaM1-1. These findings identify GW5L as a negative regulator of both grain size and salt stress tolerance, and provide a potential target for breeders to improve grain yield and salt stress resistance in rice.
粒型是作物产量潜力的一个重要决定因素。我们之前的研究表明，qSW5/GW5 调控序列的自然突变赋予了水稻粒宽的多样性。然而，GW5 同源物（命名为 GW5-Like，GW5L）的生物学功能仍然未知。在这项研究中，我们报道了 Kitaake（一种被认为具有较弱 gw5 变体等位基因的粳稻品种）中 GW5L 敲除突变体的情况，该等位基因赋予了较短和较宽的粒型。GW5L 在各种组织中均匀表达，其蛋白产物定位于质膜。生化分析验证了 GW5L 的功能与 GW5 相似。它通过抑制 GSK2 的磷酸化活性正向调节油菜素内酯（BR）信号转导。遗传数据表明，GW5L 在 Kitaake 或 GW5 敲除系 Kasa（籼稻品种 Kasalath 背景）中的过表达导致相对于野生型的粒型更细长、更长。我们还表明，GW5L 可以通过与钙调蛋白蛋白 OsCaM1-1 的关联来赋予耐盐性。这些发现表明，GW5L 是粒型和耐盐性的负调控因子，为培育具有更高产量和耐盐性的水稻提供了一个潜在的目标。
