小麦株高主效QTL–qPh-6B的精细定位及候选基因确定

PH as a decisive component of architecture affects lodging, harvest index and grain yield in wheat (Triticum aestivum L.). qPh-6B is a major stable QTL for PH detected by a RIL population derived from Kn9204 and J411, and mainly regulating the pedicel development. The pedigree tracing results indicate that the reducing height allele of Kn9204 was derived from Jimai38 which has been widely used in north part of Huanghuai wheat zone. In this project, we proposed to use 2 to 3 secondary populations and the markers developed based on the different DNA sequences of Kn9204 and J411 achieved by whole genomic sequencing to realize fine mapping. Compared the flanking markers of qPh-6B to the Kn9204 genome which has finished whole-genome sequencing, assembled and annotation and find the corresponding physical region. Further, investigate the sequences and expression differences of the annotated genes in two parents and NILs to identify the candidate gene for qPh-6B. In addition, the phenotypes of yield related traits of NILs will be investigated in multi-environment to disclose the value of qPh-6B in wheat breeding.

株高是小麦高产、稳产的关键因素之一，发掘有应用价值的新矮源，对小麦株型遗传改良和高产品种选育具有重要意义。qPh-6B是利用科农9204与京411的RIL群体检测到的新的稳定主效株高QTL，主要通过缩短穗下节间长及穗颈长（“缩脖”效应）调控株高，其降秆等位基因来自科农9204。系谱追踪表明该矮秆基因来源于冀麦38，且已在黄淮麦区北片大面积应用。本项目拟利用2-3个次级作图大群体，结合基因组重测序获得的科农9204和京411的差异序列，开发分子标记，构建靶区段饱和遗传图谱，实现qPh-6B精细定位。利用与qPh-6B紧密连锁的分子标记比对已测序、拼接和注释完成的科农9204物理序列，确定其物理区间，并分析该区间注释基因在双亲及“伸脖”与“缩脖”NIL家系间的序列及表达差异，确定候选基因。另外，多环境种植NIL家系，分析qPh-6B对产量相关性状的影响，明确其育种应用价值。

株高是小麦高产、稳产的关键因素之一，发掘有应用价值的新矮源，对小麦株型遗传改良和高产品种选育具有重要意义。qPh-6B是利用科农9204与京411的RIL群体检测到的新的稳定主效株高QTL，主要通过缩短穗下节间长及穗颈长调控株高，且在冀中南麦区广为应用。为挖掘这一有用基因，我们开展了qPh-6B的精细定位。利用双亲重测序数据，我们开发了靶区段22对共显性分子标记。利用上述标记筛选KJ-RIL高代系，在KJ27的F5:6代获得了靶区段近等基因系。近等基因系表型分析显示，靶区段为科农9204的基因型的株系株高、穗下节和穗颈长均显著低于具有京411基因型的株系，差距约10cm。通过近等基因系杂交，自交，获得了靶区段次级作图群体。利用靶区段22对共显性分子标记筛选靶区段关键交换单株，结合田间表型鉴定，将目的基因定位于6B染色体506.6kb的置信区间。搜集了黄麦区133主栽品种，建立了候选基因关联分析的自然群体，进行了多年多点表型鉴定。以上结果为qPh-6B的克隆奠定了良好的基础。