小麦芒长抑制基因B2的精细定位与候选基因分析

芒是小麦重要的穗部器官和形态特征,是小麦长期进化和适应环境的结果,对产量和抗旱性等具有重要影响。目前,对麦芒的遗传与发育还缺乏系统的研究,相关基因克隆或精细定位的研究尚未见报道。本试验利用短芒材料‘六柱头’与长芒材料‘石矮1号’构建的F2群体(SL-F2)对芒的遗传与发育进行了研究。细胞学观察表明,短芒主要是由细胞长度变短引起;遗传分析表明,‘六柱头’的短芒由显性单基因控制;借助Wheat660K SNP芯片的BSA分析和SL-F2群体的精细定位,确定‘六柱头’的芒长抑制基因是前人报道的B2位点,并将其定位到6B染色体4.84Mb的物理区间(471.28～476.12 Mb)内,该区段在中国春与矮抗58间具有良好的共线性。在B2定位区间共有61个基因,其中5个在中国春穗部特异表达,TraesCS6B02G264400在中国春和Azhurnaya幼穗表达差异显著。这些研究结果为B2基因的克隆、小麦芒形成机理的解析及育种中的应用奠定了基础。

Fine mapping and candidate gene analysis of awn inhibiting gene B2 in common wheat

Awn is one of the important photosynthetic organs in common wheat and plays a vital role in yield potential and environmental adaptation. At present, the inheritance and development of wheat awn have been not systematically studied, and cloning or fine mapping of related genes are seldom reported. In this study, the genetics and candidate genes conferring the short awn of a Chinese wheat landrace ‘Liuzhutou’ were investigated. Longitudinal section of awn showed cell size of short awn was much shorter than that of long awn. Using Wheat660K SNP chip based bulked segregant analysis (BSA) and SL-F₂ population derived from ‘Liuzhutou’ (short awn) and modern cultivar ‘Shiai 1’ (long awn), the awn inhibiting gene in ‘Liuzhutou’ was mapped in a 4.84 Mb interval on chromosome 6BL and predicted as previously characterized B2. A good micro-collinearity of B2 region was observed among chromosomes 6B, 6A, 6D of Chinese Spring and chromosome 6B of AK58, there were 61 genes annotated in the 4.84 Mb B2 region, five of which were specifically expressed in the developing spike of Chinese Spring, and TraesCS6B02G264400 was differentially expressed between Chinese Spring and Azhurnaya. These data provide important clues for cloning the B2 gene, dissecting the developing mechanism of wheat awn and its application in molecular breeding.