小麦苗期总根长QTL QTrl.saw-2D.2的精细定位及遗传效应分析

作物根系是茎叶生长和产量形成的基础，根发育基因的克隆对于揭示小麦根系形成和高产抗逆机制至关重要。总根长是根系的重要形态指标，目前小麦根长QTL/基因尚无图位克隆的报道。前期在水培和土培两种环境下，通过连锁分析和全基因组关联分析发现2D染色体上一个新的苗期总根长主效QTL QTrl.saw-2D.2，解释表型变异率为18.4%和9.1%。本项目拟开展QTrl.saw-2D.2的精细定位及效应分析，包括(1)利用2D染色体高密度图谱、小麦参考基因组信息和双亲重测序数据开发加密标记，扫描次级分离群体实现QTrl.saw-2D.2的精细定位；(2)利用近等基因系分析QTrl.saw-2D.2与根系形态和水分利用效率的关系，深入评价候选区段的遗传效应；(3)开发可用于小麦根系辅助选择的标记。项目实施有利于解析小麦根部性状的分子遗传机制，为小麦遗传改良提供新基因和新标记。

Roots are the principal plant organs for yield formation, which play essential roles in crop growth and productivity under soil-related stresses. Thus, cloning of genes involved in genetic formation of a strong root system is important to improve yield and drought tolerance in wheat. The total root length (TRL) is main composition of root system, however, the detected TRL related QTLs have not been cloned yet. Our previously results showed that a stable and major QTL QTrl.saw-2D.2 for TRL could be detected under hydroponic and soil culture, accounting for 18.4% and 9.1% of the phenotypic variance, respectively. Further, the locus identified by genome-wide association analysis was consistent with QTrl.saw-2D.2. These results indicated that QTrl.saw-2D.2 is a novel QTL for TRL. This project is mainly proposed to narrow down the QTrl.saw-2D.2 interval by scanning the secondary segregating mapping population, using polymorphic molecular markers developed based on the integrated markers on 2D linkage group, IWGSC reference sequences and resequencing information of bio-parents. In addition, to evaluate genetic effects of QTrl.saw-2D.2 on root performance, as well as water use efficiency using NIL. More importantly, to develop molecular markers that can be reliably used for marker-assisted selection in wheat breeding programs. Overall, these results will facilitate better understanding of the molecular mechanism of root growth, and establish a practical and theoretical foundation for improving drought resistance through molecular-assisted selection in wheat.