控制玉米穗行数主效QTL-qRN10的精细定位与克隆

Row number per ear is a positive contributor to maize yield, high-resolution mapping and cloning of genes controlling row number per ear will provide the basis for further biological research and have great breeding value. Previously, a major QTL on chromosome 10 controlling row number per ear (qRN10) was mapped to a 7.33Mb region. The BC6Fn (n≥2) populations are now being prepared for high-resolution mapping of qRN10. Meanwhile, the near isogenic lines (NIL) are also being prepared and will be used to compare the transcriptional differences between lines carrying contrasting alleles at qRN10. A total of 868 homozygous lines, including inbred lines, recombinant inbred lines (RIL) and multiparent advanced generation inter-cross population (MAGIC), will also be used for association study to confirm the candidate gene, which will be used to develop functional markers thereafter. This research will not only be useful for studying the molecular mechanism of row number per ear and lay the foundation for further functional genomic research, but also provide important molecular tools and references for molecular breeding application.

穗行数是决定玉米产量的重要性状，精细定位和克隆控制穗行数的基因具有重要的理论意义和育种价值。本课题前期研究中已将一个位于第10号染色体上控制穗行数的主效QTL（qRN10）定位到7.33Mb的范围内。在此基础上，本研究将利用更高世代BC6Fn（n≥2）群体实现qRN10的精细定位，同时构建qRN10的近等基因系（NIL），并对NIL和受体亲本Y1648进行转录组测序，为确定候选基因提供依据。本课题组还利用类型丰富的包括自交系群体、重组自交系群体（RIL）和多亲本高世代互交分离群体（MAGIC）的868份纯合家系进行关联分析，作为确认候选基因的参考，在此基础上开发基于目标基因的功能标记。本研究不但有利于深入研究玉米穗行数QTL的生物学意义，为进一步的功能基因组学研究奠定基础，还可为分子育种实践提供重要工具和参考。

玉米穗行数与产量密切相关，对穗行数进行精细定位有助于揭示穗行数形成的分子机理，从而为玉米产量相关性状的分子育种服务。本研究在前期研究的基础上，对玉米位于第10号染色体上的主效QTL-qRN10进行精细定位，经过连续五代的精细定位，将该位点定位到1.6 Mb的范围内，结合关联分析，将该位点进一步精细定位到360 kb的范围内，该范围内包含有一个在近等基因系之间差异表达的基因GRMZM2G139157，该基因可能是控制穗行数的候选基因。本项研究将有助于玉米穗行数的分子育种提供分子功能标记。