小麦科农9204高产、氮高效遗传基础解析

Kenong9204 (Kn9204), a wheat cultivar with high yield potential and high nitrogen use efficiency (NUE), contains the genetic materials of Xiaoyan 693, Funo, Aifeng 3 and Xiaoyan 5, characterized by diverse genetic basis. Primary QTL mapping for yield- and NUE-related traits has been conducted in eight different environments using a recombinant inbred line (RIL) population derived from the cross between Kn9204 and J411. In this project, further studies on QTL mapping for NUE, yield-related traits and seedling root characteristics will be conducted. Both unconditional and multivariable cause-effect conditional QTL mapping methods will be applied to the QTL mapping analysis, with an aim to elucidate the genetic relationships among yield-related traits, NUE, and seedling root characteristics. Moreover, fine mapping of major stable QTL clusters on 2DL, 4AL, 4BL, and 6BS will be conducted using a secondary mapping population. Origins of chromosomal segments in Kn9204 from its ancestors will be traced based on molecular marker scores, and in turn attaining the whole genome graphical genotypes of Kn9204 and especially the high-density graphical genotypes of important chromosomal regions that harbor major stable QTL clusters. The graphical genotypes will show the origins of QTL alleles with enhancing yield and NUE in Kn9204, and enable to analyze the transmission of this/these QTL in its derivatives. The aims of this research are to: 1) unravel the genetic basis of high yield and NUE in Kn9204 at the QTL level; 2) fine mapping major stable QTL clusters related to yield and NUE and evaluate their genetic effects, which will lay the foundation for their map-based cloning; 3) clarify the genetic relationships among seedling root characteristics, yield-related traits, and NUE；and 4) provide theory guide for breeding wheat cultivars with high yield and NUE.

科农9204是一个高产氮高效小麦品种，含有小偃693、阿芙乐尔、矮丰3号、小偃5号等骨干亲本或重要材料的血缘，遗传基础丰富。本项目拟基于科农9204×京411重组自交系群体8个环境下产量、氮效率初级QTL定位基础上，进一步开展产量、氮效率和苗期根系形态等相关性状的非条件和原因/结果条件QTL分析，并利用次级作图群体对2DL、4AL、4BL、6BS重要染色体区段的产量、氮效率相关的多环境稳定表达主效QTL簇进行精细作图。结合科农9204原始亲本及其衍生后代基因型值，绘制科农9204全基因组图示基因型及关键染色体区段精细图示基因型，以期在DNA水平揭示科农9204高产、氮高效的遗传基础，解析重要染色体区段QTL簇遗传效应，为高产、氮高效主效QTL图位克隆奠定基础，为高产、氮高效品种选育提供理论指导。

本项目基于前期科农9204×京411重组自交系群体多环境下产量、氮效率初级QTL 定位基础上，开展了产量、氮效率和苗期根系形态等相关性状的非条件和原因/结果条件QTL 分析，并利用次级作图群体对2DL、4AL、4BL、6BS 重要染色体区段的产量、氮效率相关的多环境稳定表达主效QTL 簇进行精准作图。利用Affymetrix wheat 660K SNP芯片构建了包含11.96万个位点高密度遗传连锁图谱。结合科农9204 原始亲本及其衍生后代基因型值，绘制了科农9204 全基因组图示基因型及关键染色体区段精细图示基因型，在DNA水平揭示了科农9204 高产、氮高效的遗传基础，解析了2DL、4AL、4BL、6BS 重要染色体区段QTL 簇遗传效应。此外，在1B、2A、4B、5A、5D及7A染色体存在响应氮胁迫的多环境稳定表达QTL位点，其中4B染色体来自科农9204的Rht-B1b等位基因增强其低氮耐受性，为科农9204高产氮高效重要遗传基础。研究结果为高产、氮高效主效QTL 图位克隆奠定基础，为高产、氮高效品种选育提供理论指导。