15-IWYP: Molecular Dissection of Spike Yield Components in Wheat

我们面临的一个重大挑战是理解小麦产量潜力的遗传结构。我们提出了一种系统的遗传方法来识别穗和籽粒发育早期阶段潜在的发育瓶颈。我们假设，这种方法将有助于识别新的等位基因变异，将提供小麦产量潜力的逐步变化。提高小麦产量需要同时改善“源”和“库”，并且必须一起研究各种产量组成部分，以解决其中一些性状（例如粒数和重量）之间存在的已知负相关。然而，一个还原论和系统的方法可以被用来作为第一步，以了解基因网络调节每个单独的产量组成部分。然后可以应用这些知识来组装最佳等位基因组合。这个建议是集中在'汇'方面的方程，特别是在每穗的颗粒数和单个颗粒的大小的同时增加。这些产量构成因素主要是在穗和心皮/籽粒发育的早期阶段的一个相对狭窄和明确的窗口期间确定的。我们建议把重点放在穗和心皮/籽粒发育的关键早期阶段，联合收割机有利的等位基因先前确定我们的小组，并利用外显子组测序的四倍体和六倍体TILLING（靶向诱导的基因组局部病变）人口，以确定新的等位基因变异。过去的小麦TILLING群体将允许快速评估无效双突变体中的基因，而面包小麦群体将补充这种方法，并允许部署到优秀的面包小麦品种中。在这个项目中，我们将确定和鉴定一组调节粒数和重量的基因，并开发新的等位基因组合，以提高小麦的总穗产量。我们已经验证了一组自然的和新的诱导等位基因变异的TILLING群体，影响特定的穗产量组件，并系统地开发了种质资源，技术和功能基因组学资源，以解决提出的目标。我们将利用新兴的基因组进展，并将与育种家密切合作，迅速将这种变异引入CIMMYT种质。该项目中产生的变异和等位基因组合以前没有在传统的小麦育种计划中使用过，因此，代表了在小麦遗传产量潜力方面取得重大进展的前所未有的机会。（1）鉴定和定性（分子，（2）产生靶向所选基因的所有同源物的双重和三重突变体以克服功能冗余（3）利用影响互补穗产量构成因素的新等位基因组合产生适应种质

We face a major challenge in understanding the genetic architecture of yield potential in wheat. We propose a systematic genetic approach to identify potential developmental bottlenecks in the early stages of spike and grain development. We hypothesise that this approach will contribute to the identification of novel allelic variation that will deliver step-changes in wheat yield potential. Increasing wheat yields will require simultaneous improvements of both the 'source' and 'sink' and that the various yield components must be studied together to address the known negative correlations that exist between some of these traits (e.g. grain number and weight). However, a reductionist and systematic approach can be used as an initial step to understand the gene networks regulating each individual yield component. This knowledge can then be applied to assemble the best allelic combinations. This proposal is focused on the 'sink' side of the equation and specifically on the simultaneous increase of the number of grains per spike and the size of the individual grains. These yield components are mainly determined during a relatively narrow and well-defined window in the early stages of spike and carpel/grain development. We propose to focus on the critical early periods of spike and carpel/grain development, combine favourable alleles previously identified by our groups, and exploit exome sequenced tetraploid and hexaploid TILLING (Targeting Induced Local Lesions in Genomes) populations to identify novel allelic variants. The past wheat TILLING population will allow rapid evaluation of genes in null double-mutants, whereas the bread wheat population will complement this approach and allow deployment into elite bread wheat varieties.In this project we will identify and characterise a set of genes regulating grain number and weight, and develop novel allelic combinations to enhance overall spike yield in wheat. We have validated a set of both natural and novel induced allelic variants from the TILLING populations that affect specific spike yield components and have systematically developed the germplasm, techniques, and functional genomics resources required to address the proposed objectives. We will exploit emerging genomic advances and will work closely with breeders to rapidly introduce this variation into CIMMYT germplasm. The variation and allelic combinations generated within this project have not previously been utilised in traditional wheat breeding programmes and, therefore, represent an unprecedented opportunity to make significant progress in the genetic yield potential of wheat.The main direct outcomes expected from this research are: (1) Identification and characterisation (molecular, physiological and agronomic) of novel gene variants controlling wheat spike yield components (2) Creation of double and triple mutants targeting all homoeologs for the selected genes to overcome functional redundancy(3) Generation of adapted germplasm with new allelic combinations affecting complementary spike yield components