小麦粒重基因TaTGW-A1的克隆及分子机制解析

粒重是决定小麦高产的关键目标性状。挖掘粒重关键调控基因，针对粒重进行分子遗传改良，是实现小麦高产分子育种的重要策略。目前，育种可用的粒重基因资源十分匮乏，严重制约了小麦高产分子遗传改良进程。申请人团队前期利用小麦材料ND3026（小粒）和ND3999（大粒）构建分离群体在7A染色体发现1个控制粒重的主效QTL，命名为TaTGW-A1。利用剩余杂合系衍生的分离群体进行精细定位，将目标QTL缩小至78.6kb范围内，包含2个候选基因。利用近等基因系证明，该位点可提高千粒重2.5g以上，且对分蘖、抽穗期、成熟期等重要农艺性状无不良影响，具有很好的育种利用潜力。本项目拟采用遗传学与生物化学相结合的策略，克隆TaTGW-A1基因，并对其生物学功能和分子作用机制进行深入解析，同时对该基因的育种利用价值和增产潜力进行评估，以期为小麦高产分子遗传改良和现代快速育种提供重要基因资源和理论依据。

Grain weight is one of the key traits for high-yielding wheat varieties. Cloning of grain weight genes and further characterization of their molecular functions will greatly facilitate the wheat genetic improvement in the on-farm yield. However, the genetic basis of how the grain development is controlled and how final grain weight is influenced is largely unknown. By using recombinant inbred lines (RILs) derived from two wheat varieties (ND3026 and ND3999) with different grain weight, we previously identified a major QTL for grain weight on chromosome 7A, which we named as TaTGW-A1. Further fine mapping using the segregating population derived from the residual heterozygous line (RHL) narrowed the candidate gene to a 78.6 kb region between markers M4 and M15, containing two protein-coding genes. This locus could increase the thousand grain weight (TGW) by ~2.5 g without affecting other major agronomic traits, including plant height, tillering, heading time and maturation, suggesting that TaTGW-A1 may be potentially utilized in wheat breeding. Based on the above knowledge, this proposed project is designed to finally clone the candidate gene of TaTGW-A1. Meanwhile, the molecular regulation mechanism of TaTGW-A1 on grain weight will be explored by combining the genetic and biochemical research strategies. In the end, the breeding utilization value of TaTGW will be analyzed and discussed. This proposed project will be of significance for molecular-associated genetic improvement of wheat yield potential.