小麦产量三因素形成和互作的遗传控制机制研究

The yield of grain crops is determined by three yield components, i.e., productive spikes per unit area, kernels per spike and kernel weight. Their coordination optimization is critical for high yield improvement. Both wheat and rice are Gramineae grain crops. Although dozens of yield component-related QTLs have been cloned in rice, the genetic control mechanisms underlying the formation and interactions of the three yield components are still not clear. In our previous studies, we have identified 14 chromosome regions in wheat showing significant association with the three components through QTL mapping and association analysis. Many of these regions, for example those located on chromosome 4BL and 5AS, affected multiple traits. In this study, we propose to precisely map these QTLs, investigate the genetic effects of their allelic variations and interactions, and characterize the collinear relationships of these wheat QTL intervals with known yield-related genes and the homologous wheat genes. Since our data indicated that the mentioned 4BL and 5AS QTLs might not be homologous to the known yield genes, we also propose to clone these two QTLs and characterize their functions. Through these studies, we aim at dissecting the genetic mechanisms underlying wheat yield component formation, exploring high yield-related new genes or allelic variations, eventually developing theoretical basis and genetic resources for high yield breeding.

小麦单位面积产量取决于产量三因素：单位面积有效穗数、每穗粒数和粒重；实现对它们的优化调控对高产育种至关重要。小麦和水稻同属禾本科植物。虽然已有多个水稻产量因素 QTL被克隆，但是产量三因素形成和互作的遗传控制机制仍然不清楚。我们通过QTL和关联分析在小麦中确定了14个对产量三因素有显著影响的染色体区段。其中多个区段，如位于4BL和5AS上的QTL区段，影响多个性状。本项目拟在此基础上，进行小麦产量三因素QTL的精确定位和它们的等位变异及其遗传效应与互作关系的解析；确定这些QTL与水稻等物种中已知产量相关基因的同源关系并分析小麦同源基因的功能。有证据表明4BL和5AS上的QTL区段与已知产量相关基因不存在共线性关系。为此，本项目拟克隆这两个QTL并阐明其功能。上述研究将有助于解析小麦产量三因素形成的遗传控制机制，发掘优异的高产基因或等位变异，为小麦高产育种提供基因资源和理论基础。

小麦单位面积产量取决于产量三因素：单位面积有效穗数、每穗粒数和粒重;实现对它们的优化调控对高产育种至关重要。旨在了解小麦产量三因素形成和互作的遗传控制机制，本项目开展了产量因素相关QTL的精确定位、QTL等位变异及其遗传效应与互作关系的解析、以及两个主要QTL的克隆及功能分析等方面的研究。图位克隆了穗长主效QTL HL1，精细定位了旗叶宽基因TaFLW1和粒重主效QTL QGw.nau-5A并获得了候选基因。HL1编码一个未知核蛋白，正调控穗长。克隆了小麦株型相关基因TmBr1和TmITR，并建立了小麦重组冷点区基因克隆的MapRseq方法。完成了一个粒重主效QTL、一个籽粒发育QTL和一个穗长主效QTL（HL2）的精细定位；通过反向遗传分析，获得了一个重要籽粒发育相关基因；明确了籽粒形态特征与粒重的关系以及小麦驯化基因Q与产量形成的相关性；获得了16个基因组区段在不同遗传背景中的近等基因系，评价了其中8个的效应。研究中获得的与QTL紧密连锁的标记已被成功用于QTL的分子标记辅助选择中。对利用克隆基因获得的转基因植株，正在做相关性状的进一步评价。研究创造的新种质包括近等基因系，不仅可用于QTL的深入研究，还可作为育种的中间材料，部分材料具有直接利用的潜力。