National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, PR China.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, PR China.
Plant Sci. 2019 Nov;288:110205. doi: 10.1016/j.plantsci.2019.110205. Epub 2019 Jul 29.
Maize kernel size and weight are essential contributors to its yield. So the identification of the genes controlling kernel size and weight can give us a chance to gain the yield. Here, we identified a small kernel mutant, Zea mays small kernel 9 (Zmsmk9), in maize. Cytological observation showed that the development of the endosperm and embryo was delayed in Zmsmk9 mutants at the early stages, resulting in a small kernel phenotype. Interestingly, despite substantial variation in kernel size, the germination of Zmsmk9 seeds was comparable to that of WT, and could develop into normal plants with upright leaf architecture. We cloned Zmsmk9 via map-based cloning. ZmSMK9 encodes a P-type pentatricopeptide repeat protein that targets to mitochondria, and is involved in RNA splicing in mitochondrial NADH dehydrogenase5 (nad5) intron-1 and intron-4. Consistent with the delayed development phenotype, transcriptome analysis of 12-DAP endosperm showed that starch and zeins biosynthesis related genes were dramatically down regulated in Zmsmk9, while cell cycle and cell growth related genes were dramatically increased. As a result, ZmSMK9 is a novel gene required for the splicing of nad5 intron-1 and intron-4, kernel development, and plant architecture in maize.
玉米子粒大小和重量是其产量的重要贡献因素。因此，鉴定控制子粒大小和重量的基因可以为我们提供提高产量的机会。在这里，我们在玉米中鉴定到一个小粒突变体，Zea mays small kernel 9（Zmsmk9）。细胞学观察表明，Zmsmk9 突变体在早期阶段胚乳和胚胎的发育被延迟，导致小粒表型。有趣的是，尽管子粒大小有很大差异，但 Zmsmk9 种子的萌发与 WT 相当，并且可以发育成具有直立叶结构的正常植物。我们通过图谱定位克隆克隆了 Zmsmk9。ZmSMK9 编码一种 P 型五肽重复蛋白，靶向线粒体，参与线粒体 NADH 脱氢酶 5（nad5）内含子 1 和内含子 4 的 RNA 剪接。与延迟发育表型一致，12-DAP 胚乳的转录组分析表明，Zmsmk9 中与淀粉和醇溶蛋白生物合成相关的基因显著下调，而与细胞周期和细胞生长相关的基因显著上调。因此，ZmSMK9 是一个新的基因，对于 nad5 内含子 1 和内含子 4 的剪接、子粒发育和玉米的植物结构是必需的。
