Tao Yongfu, Trusov Yuri, Zhao Xianrong, Wang Xuemin, Cruickshank Alan W, Hunt Colleen, van Oosterom Erik J, Hathorn Adrian, Liu Guoquan, Godwin Ian D, Botella Jose R, Mace Emma S, Jordan David R
Queensland Alliance for Agriculture and Food Innovation (QAAFI), Hermitage Research Facility, The University of Queensland, Warwick, Qld, 4370, Australia.
School of Agriculture and Food Sciences, The University of Queensland, Brisbane, Qld, 4072, Australia.
Plant J. 2021 Oct;108(1):231-243. doi: 10.1111/tpj.15437. Epub 2021 Aug 13.
Variation in grain size, a major determinant of grain yield and quality in cereal crops, is determined by both the plant's genetic potential and the available assimilate to fill the grain in the absence of stress. This study investigated grain size variation in response to variation in assimilate supply in sorghum using a diversity panel (n = 837) and a backcross-nested association mapping population (n = 1421) across four experiments. To explore the effects of genetic potential and assimilate availability on grain size, the top half of selected panicles was removed at anthesis. Results showed substantial variation in five grain size parameters with high heritability. Artificial reduction in grain number resulted in a general increase in grain weight, with the extent of the increase varying across genotypes. Genome-wide association studies identified 44 grain size quantitative trait locus (QTL) that were likely to act on assimilate availability and 50 QTL that were likely to act on genetic potential. This finding was further supported by functional enrichment analysis and co-location analysis with known grain number QTL and candidate genes. RNA interference and overexpression experiments were conducted to validate the function of one of the identified gene, SbDEP1, showing that SbDEP1 positively regulates grain number and negatively regulates grain size by controlling primary branching in sorghum. Haplotype analysis of SbDEP1 suggested a possible role in racial differentiation. The enhanced understanding of grain size variation in relation to assimilate availability presented in this study will benefit sorghum improvement and have implications for other cereal crops.
籽粒大小变异是谷类作物产量和品质的主要决定因素，它由植物的遗传潜力以及在无胁迫条件下用于充实籽粒的可用同化物共同决定。本研究利用一个包含837份材料的多样性群体和一个回交-巢式关联作图群体（1421份材料），通过四个试验研究了高粱籽粒大小对同化物供应变化的响应。为探究遗传潜力和同化物可利用性对籽粒大小的影响，在开花期去除了所选穗子的上半部分。结果表明，五个籽粒大小参数存在显著变异，且遗传力较高。人工减少籽粒数量导致粒重普遍增加，增加幅度因基因型而异。全基因组关联研究确定了44个可能作用于同化物可利用性的籽粒大小数量性状位点（QTL）和50个可能作用于遗传潜力的QTL。功能富集分析以及与已知籽粒数量QTL和候选基因的共定位分析进一步支持了这一发现。通过RNA干扰和过表达实验对其中一个已鉴定基因SbDEP1的功能进行了验证，结果表明SbDEP1通过控制高粱的一次分枝正向调控籽粒数量，负向调控籽粒大小。SbDEP1的单倍型分析表明其在品种分化中可能发挥作用。本研究对籽粒大小变异与同化物可利用性之间关系的深入理解将有助于高粱改良，并对其他谷类作物具有启示意义。
