Cao Fubin, Wei Ruru, Xie Jianguo, Hou Lilong, Kang Chaorui, Zhao Tianyu, Sun Chengcheng, Yang Mingliang, Zhao Ying, Li Candong, Wang Nannan, Wu Xiaoxia, Liu Chunyan, Jiang Hongwei, Chen Qingshan
College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China.
Jilin Academy of Agricultural Sciences, Soybean Research Institute, Changchun, Jilin, China.
Front Plant Sci. 2023 Jan 18;13:1104022. doi: 10.3389/fpls.2022.1104022. eCollection 2022.
Soybean yield, as one of the most important and consistent breeding goals, can be greatly affected by the proportion of four-seed pods (PoFSP). In this study, QTL mapping was performed by PoFSP data and BLUE (Best Linear Unbiased Estimator) value of the chromosome segment substitution line population (CSSLs) constructed previously by the laboratory from 2016 to 2018, and phenotype-based bulked segregant analysis (BSA) was performed using the plant lines with PoFSP extreme phenotype. Totally, 5 ICIM QTLs were repeatedly detected, and 6 BSA QTLs were identified in CSSLs. For QTL () repeated in ICIM and BSA results, the secondary segregation populations were constructed for fine mapping and the interval was reduced to 100Kb. The mapping results showed that the QTL had an additive effect of gain from wild parents. A total of 14 genes were annotated in the delimited interval by fine mapping. Sequence analysis showed that all 14 genes had genetic variation in promoter region or CDS region. The qRT-PCR results showed that a total of 5 candidate genes were differentially expressed between the plant lines having antagonistic extreme phenotype (High PoFSP > 35.92%, low PoFSP< 17.56%). The results of haplotype analysis showed that all five genes had two or more major haplotypes in the resource population. Significant analysis of phenotypic differences between major haplotypes showed all five candidate genes had haplotype differences. And the genotypes of the major haplotypes with relatively high PoFSP of each gene were similar to those of wild soybean. The results of this study were of great significance to the study of candidate genes affecting soybean PoFSP, and provided a basis for the study of molecular marker-assisted selection (MAS) breeding and four-seed pods domestication.
大豆产量作为最重要且稳定的育种目标之一，会受到四粒荚比例（PoFSP）的显著影响。本研究利用PoFSP数据以及实验室先前于2016年至2018年构建的染色体片段代换系群体（CSSLs）的最佳线性无偏估计值（BLUE）进行QTL定位，并对具有PoFSP极端表型的株系进行基于表型的混合分组分析法（BSA）。总共重复检测到5个ICIM QTL，在CSSLs中鉴定出6个BSA QTL。对于在ICIM和BSA结果中重复出现的QTL，构建次级分离群体进行精细定位，区间缩小至100Kb。定位结果表明该QTL具有来自野生亲本的增效加性效应。精细定位在划定区间共注释到14个基因。序列分析表明，这14个基因在启动子区或编码区均存在遗传变异。qRT-PCR结果显示，在具有拮抗极端表型（高PoFSP > 35.92%，低PoFSP < 17.56%）的株系间，共有5个候选基因差异表达。单倍型分析结果表明，这5个基因在资源群体中均具有两种或更多种主要单倍型。主要单倍型间表型差异的显著性分析表明，所有5个候选基因均存在单倍型差异。且每个基因PoFSP相对较高的主要单倍型的基因型与野生大豆相似。本研究结果对影响大豆PoFSP的候选基因研究具有重要意义，为分子标记辅助选择（MAS）育种及四粒荚驯化研究提供了依据。
