Chen Wei, Yao Jinbo, Chu Li, Yuan Zhengwen, Li Yan, Zhang Yongshan
State Key Laboratory of Cotton Biology, Institute of Cotton Research, The Chinese Academy of Agricultural Sciences, Anyang, 455004, China.
Theor Appl Genet. 2015 Mar;128(3):539-47. doi: 10.1007/s00122-014-2452-2. Epub 2015 Jan 10.
Using bulked segregant analysis based on next-generation sequencing, the recessive nulliplex-branch gene was mapped between two SNP markers ~600 kb apart. In a "nulliplex-branch" cotton mutant, most of the flowers arise directly from leaf axils on the main shoot, which usually does not have a fruiting branch. A nulliplex-branch is a useful trait by which to study cotton architecture; however, the genetic basis of this mutant has remained elusive. In this study, bulked segregant analysis combined with next-generation sequencing technology was used to finely map the underlying genes that result in a nulliplex-branch plant. The nulliplex-branch Pima cotton variety, Xinhai-18, was crossed with the normal branch upland cotton line, TM-1, resulting in an F2 population. The nulliplex-branch trait was found to be controlled by the recessive gene gb_nb1. Allelic single-nucleotide polymorphisms (SNPs) were discovered by reduced-representation sequencing between the parents, and their profiles were also characterized in the nulliplex-branch and normal branch bulks constructed using the F2 plants. A candidate ~9.0 Mb-long region comprising 42 SNP markers was found to be associated with gb_nb1, which helped localize it at the ~600-kb interval on Chr 16 by segregation analysis in the F2 population. The closely linked markers with gb_nb1 developed in this study will facilitate the marker-assisted selection of the nulliplex-branch trait, and the fine map constructed will accelerate map-based cloning of gb_nb1.
利用基于二代测序的混合分组分析法，将隐性无果枝基因定位在两个相距约600 kb的单核苷酸多态性（SNP）标记之间。在一个“无果枝”棉花突变体中，大多数花朵直接从主茎的叶腋处生出，主茎通常没有果枝。无果枝是研究棉花株型的一个有用性状；然而，该突变体的遗传基础一直不清楚。在本研究中，采用混合分组分析法结合二代测序技术对导致无果枝植株的潜在基因进行精细定位。将无果枝海岛棉品种新海18与正常果枝陆地棉品系TM-1杂交，获得F2群体。发现无果枝性状受隐性基因gb_nb1控制。通过对亲本进行简化基因组测序发现了等位单核苷酸多态性（SNP），并在利用F2植株构建的无果枝和正常果枝混合群体中对其图谱特征进行了分析。发现一个包含42个SNP标记、长度约为9.0 Mb的候选区域与gb_nb1相关，通过对F2群体的分离分析将其定位在第16号染色体上约600 kb的区间内。本研究开发的与gb_nb1紧密连锁的标记将有助于无果枝性状的分子标记辅助选择，构建的精细图谱将加速gb_nb1的图位克隆。
