Shen Qi, Wang Kai, Hu Lu, Li Lei, Wang Lihua, Wang Yongfei, Wang Yi-Hong, Li Jieqin
College of Agriculture, Anhui Science and Technology University, Fengyang 233100, China.
International Joint Research Center of Forage Bio-Breeding in Anhui Province, Chuzhou 233100, China.
Plants (Basel). 2025 Jun 11;14(12):1791. doi: 10.3390/plants14121791.
Grain size is a crucial agronomic trait that significantly impacts yield potential in sorghum (), making it a key focus for genetic improvement. In this study, we investigated the genetic basis of grain size variation using two contrasting sorghum accessions, PI302232 (small grain, Sg) and PI563512 (large grain, Lg). The 1000-grain weight, grain length, and grain width of Lg were 3.63-fold, 1.22-fold, and 1.65-fold higher than Sg, respectively. The 1000-grain weight in the F segregating population derived from the cross Sg and Lg parents exhibited the highest phenotypic variation and followed a normal distribution in the three traits. Using bulked segregant analysis sequencing (BSA-seq) with small- and large-grain bulks from the F population, two major quantitative trait loci (QTLs) for grain size were identified on chromosomes 1 and 3. Fine mapping with SSR markers narrowed the locus to a 1.03 Mb region on chromosome 1 (Chr01: 22,001,448-23,035,593), containing 49 candidate genes. To narrow down potential candidate genes, transcriptome analysis of spike tissues from Sg and Lg at 0 and 14 days after heading revealed 3719 differentially expressed genes (DEGs), primarily enriched in "starch and sucrose metabolism" and "phenylpropanoid biosynthesis" pathways. Integrating fine mapping intervals and RNA-seq data, 6 DEGs were identified within the region. Quantitative real-time PCR confirmed that 6 genes exhibited different expression at two stages. The expression and bioinformatics analysis showed Sobic.001G230700 was the most likely candidate gene for the qGS1 locus. This study provides new insights into the genetic regulation of grain size and a new target to improve grain size in sorghum.
粒重是高粱中一个至关重要的农艺性状，对产量潜力有显著影响，因此成为遗传改良的关键重点。在本研究中，我们使用两个对比鲜明的高粱种质PI302232（小粒，Sg）和PI563512（大粒，Lg）研究了粒重变异的遗传基础。Lg的千粒重、粒长和粒宽分别比Sg高3.63倍、1.22倍和1.65倍。来自Sg和Lg亲本杂交的F分离群体中的千粒重在这三个性状中表现出最高的表型变异且呈正态分布。通过对F群体中小粒和大粒混合样本进行混合分组分析法测序（BSA-seq），在第1和第3号染色体上鉴定出两个控制粒重的主要数量性状位点（QTL）。利用SSR标记进行精细定位将该位点缩小到第1号染色体上一个1.03 Mb的区域（Chr01: 22,001,448 - 23,035,593），该区域包含49个候选基因。为了缩小潜在候选基因范围，对抽穗后0天和14天的Sg和Lg穗组织进行转录组分析，发现3719个差异表达基因（DEG），主要富集在“淀粉和蔗糖代谢”以及“苯丙烷生物合成”途径中。整合精细定位区间和RNA-seq数据，在该区域内鉴定出6个DEG。定量实时PCR证实6个基因在两个阶段表现出不同表达。表达和生物信息学分析表明Sobic.001G230700是qGS1位点最有可能的候选基因。本研究为高粱粒重的遗传调控提供了新见解，并为提高高粱粒重提供了新靶点。
