Zou Guihua, Zhai Guowei, Yan Song, Li Sujuan, Zhou Lengbo, Ding Yanqing, Liu Heqin, Zhang Zhipeng, Zou Jianqiu, Zhang Liyi, Chen Junping, Xin Zhanguo, Tao Yuezhi
Institute of Crop and Nuclear Technology Utilization, State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
Rice National Engineering Laboratory, Rice Research Institute, Jiangxi Academy of Agricultural Sciences, Nanchang, China.
J Exp Bot. 2020 Sep 19;71(18):5389-5401. doi: 10.1093/jxb/eraa277.
Grain size is a major determinant of grain yield in sorghum and other cereals. Over 100 quantitative trait loci (QTLs) of grain size have been identified in sorghum. However, no gene underlying any grain size QTL has been cloned. Here, we describe the fine mapping and cloning of one grain size QTL. From an F8 recombinant inbred line population derived from a cross between inbred lines 654 and LTR108, we identified 44 grain size QTLs. One QTL, qTGW1a, was detected consistently on the long arm of chromosome 1 in the span of 4 years. Using the extreme recombinants from an F2:3 fine-mapping population, qTGW1a was delimited within a ~33 kb region containing three predicted genes. One of them, SORBI_3001G341700, predicted to encode a G-protein γ subunit and homologous to GS3 in rice, is likely to be the causative gene for qTGW1a. qTGW1a appears to act as a negative regulator of grain size in sorghum. The functional allele of the putatively causative gene of qTGW1a from inbred line 654 decreased grain size, plant height, and grain yield in transgenic rice. Identification of the gene underlying qTGW1a advances our understanding of the regulatory mechanisms of grain size in sorghum and provides a target to manipulate grain size through genome editing.
粒重是高粱和其他谷物产量的主要决定因素。在高粱中已鉴定出100多个粒重数量性状位点（QTL）。然而，尚未克隆出任何粒重QTL的潜在基因。在此，我们描述了一个粒重QTL的精细定位和克隆。从自交系654和LTR108杂交衍生的F8重组自交系群体中，我们鉴定出44个粒重QTL。一个QTL，qTGW1a，在4年的时间跨度内始终在第1号染色体长臂上被检测到。利用F2:3精细定位群体中的极端重组体，qTGW1a被限定在一个约33 kb的区域内，该区域包含三个预测基因。其中一个，SORBI_3001G341700，预测编码一个G蛋白γ亚基且与水稻中的GS3同源，可能是qTGW1a的致病基因。qTGW1a似乎在高粱中作为粒重的负调控因子起作用。来自自交系654的qTGW1a假定致病基因的功能等位基因降低了转基因水稻的粒重、株高和籽粒产量。qTGW1a潜在基因的鉴定推进了我们对高粱粒重调控机制的理解，并为通过基因组编辑操纵粒重提供了一个靶点。
