Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China.
Key Laboratory of National Forestry and Grassland Administration on Biodiversity Conservation in Karst Mountainous Areas of Southwestern China, School of Life Science, Guizhou Normal University, Guiyang, China.
Plant J. 2022 Jun;110(5):1397-1414. doi: 10.1111/tpj.15746. Epub 2022 Apr 17.
La proteins are found widely in eukaryotes and play a variety of vital roles. AtLa1 has been identified as an La protein that is necessary for embryogenesis in Arabidopsis; however, the existence and biological functions of La proteins in rice (Oryza sativa L.) remain unclear. In this study, we identified and characterized two La proteins in rice that are homologous to AtLa1 and named them OsLa1 and OsLa2. Both the OsLa1 and OsLa2 genes encode RNA-binding proteins with an La domain and two RNA-binding domains. Mutant OsLa1 reduced grain length and pollen fertility, whereas OsLa1 overexpression caused the opposite phenotypes. Further experiments indicated that OsLa1 modulates grain size by influencing cell expansion. Interestingly, mutant OsLa2 resulted in thin grains with decreased weight and a low seed-setting rate. We also found that OsLa1 interacted with OsLa2 and that both OsLa1 and OsLa2 interacted with OseIF6.1, a eukaryotic translation initiation factor involved in ribosome biogenesis. In addition, OsLa1 was able to bind to OseIF6.1 mRNA to modulate its expression. Complete OseIF6.1 knockout caused lethality and OseIF6.1/oseif6.1 heterozygous plants displayed low fertility and low seed setting. Together, our results enrich our knowledge of the role of La proteins in rice growth and development, as well as the relationship between La and eIF6 in rice.
La 蛋白广泛存在于真核生物中，发挥着多种重要作用。AtLa1 被鉴定为拟南芥胚胎发生所必需的 La 蛋白，但 La 蛋白在水稻（Oryza sativa L.）中的存在和生物学功能尚不清楚。在本研究中，我们鉴定并表征了水稻中与 AtLa1 同源的两个 La 蛋白，命名为 OsLa1 和 OsLa2。OsLa1 和 OsLa2 基因均编码具有 La 结构域和两个 RNA 结合结构域的 RNA 结合蛋白。OsLa1 突变体导致粒长变短和花粉育性降低，而 OsLa1 过表达则导致相反的表型。进一步的实验表明，OsLa1 通过影响细胞扩张来调节粒大小。有趣的是，OsLa2 突变体导致粒变薄，重量降低，结实率低。我们还发现 OsLa1 与 OsLa2 相互作用，并且 OsLa1 和 OsLa2 都与参与核糖体生物发生的真核翻译起始因子 OseIF6.1 相互作用。此外，OsLa1 能够结合 OseIF6.1 mRNA 来调节其表达。OseIF6.1 完全敲除导致致死性，而 OseIF6.1/oseif6.1 杂合子植物表现出低育性和低结实率。总之，我们的研究结果丰富了我们对 La 蛋白在水稻生长发育中的作用以及 La 与 eIF6 在水稻中的关系的认识。
