Jiang Liangrong, Li Guotian, Chern Mawsheng, Jain Rashmi, Pham Nhan T, Martin Joel A, Schackwitz Wendy S, Zhao Juan, Ruan Deling, Huang Rongyu, Zheng Jingsheng, Ronald Pamela C
Xiamen Plant Genetics Key Laboratory, School of Life Sciences, Xiamen University, Xiamen, 361102, People's Republic of China.
Department of Plant Pathology and the Genome Center, University of California, Davis, CA, 95616, USA.
Rice (N Y). 2019 Jul 18;12(1):52. doi: 10.1186/s12284-019-0308-8.
Breeding for genes controlling key agronomic traits is an important goal of rice genetic improvement. To gain insight into genes controlling grain morphology, we screened M plants derived from 1,000 whole-genome sequenced (WGS) M Kitaake mutants to identify lines with altered grain size.
In this study, we isolated a mutant, named fast-neutron (FN) 60-4, which exhibits a significant reduction in grain size. We crossed FN60-4 with the parental line Kitaake and analyzed the resulting backcross population. Segregation analysis of 113 lines from the BCF population revealed that the mutant phenotype is controlled by a single semi-dominant locus. Mutant FN60-4 is reduced 20% in plant height and 8.8% in 1000-grain weight compared with Kitaake. FN60-4 also exhibits an 8% reduction in cell number and a 9% reduction in cell length along the vertical axis of the glume. We carried out whole-genome sequencing of DNA pools extracted from segregants with long grains or short grains, and revealed that one gene, LOC_Os09g02650, cosegregated with the grain size phenotype in the BCF and BCF populations. This mutant allele was named grain shape 9-1 (gs9-1). gs9-1 carries a 3-bp deletion that affects two amino acids. This locus is a new allele of the BC12/GDD1/MTD1 gene that encodes a kinesin-like protein involved in cell-cycle progression, cellulose microfibril deposition and gibberellic acid (GA) biosynthesis. The GA biosynthesis-related gene KO2 is down-regulated in gs9-1. The dwarf phenotype of gs9-1 can be rescued by adding exogenous GA. In contrast to the phenotypes for the other alleles, the gs9-1 is less severe, consistent with the nature of the mutation, which does not disrupt the open reading frame as observed for the other alleles.
In this study, we isolated a mutant, which exhibits altered grain shape and identified the mutated gene, gs9-1. Our study reveals that gs9-1 is a semi-dominant gene that carries a two-amino acid mutation. gs9-1 is allelic to the BC12/GDD1/MTD1 gene involved in GA biosynthesis. These results demonstrate the efficiency and convenience of cloning genes from the whole-genome sequenced Kitaake mutant population to advance investigations into genes controlling key agronomic traits in rice.
培育控制关键农艺性状的基因是水稻遗传改良的重要目标。为深入了解控制籽粒形态的基因，我们筛选了来自1000个全基因组测序（WGS）的 Kitaake 突变体的 M 植株，以鉴定籽粒大小发生改变的株系。
在本研究中，我们分离出一个名为快中子（FN）60 - 4 的突变体，其籽粒大小显著减小。我们将 FN60 - 4 与亲本 Kitaake 杂交，并分析所得的回交群体。对来自 BCF 群体的113个株系进行分离分析表明，突变表型由单个半显性位点控制。与 Kitaake 相比，突变体 FN60 - 4 的株高降低了20%，千粒重降低了8.8%。FN60 - 4 在颖壳垂直轴上的细胞数量减少了8%，细胞长度减少了9%。我们对从长粒或短粒分离群体中提取的DNA池进行了全基因组测序，发现在BCF和BCF群体中，一个基因LOC_Os09g02650与籽粒大小表型共分离。这个突变等位基因被命名为粒形9 - 1（gs9 - 1）。gs9 - 1携带一个3碱基缺失，影响两个氨基酸。该位点是BC12/GDD1/MTD1基因的一个新等位基因，该基因编码一种参与细胞周期进程、纤维素微纤丝沉积和赤霉素（GA）生物合成的类驱动蛋白。与GA生物合成相关的基因KO2在gs9 - 1中下调。gs9 - 1的矮化表型可以通过添加外源GA来挽救。与其他等位基因的表型不同，gs9 - 1的表型不那么严重，这与突变的性质一致，即它不像其他等位基因那样破坏开放阅读框。
在本研究中，我们分离出一个表现出籽粒形状改变的突变体，并鉴定出突变基因gs9 - 1。我们的研究表明，gs9 - 1是一个携带两个氨基酸突变的半显性基因。gs9 - 1与参与GA生物合成的BC12/GDD1/MTD1基因等位。这些结果证明了从全基因组测序的 Kitaake 突变体群体中克隆基因以推进对水稻关键农艺性状控制基因研究的效率和便利性。
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