Source-sink balance in wheat under abiotic stress: Dissecting the spatio-temporal dynamics of grain filling

小麦是最重要的主食作物之一，粮食高产对全球粮食安全至关重要。在广泛的以前的工作中，我们证实了小麦产量潜力的限制主要是由源-库关系中涉及的性状决定的：现代品种显示出生物量，养分利用效率，收获指数，光截获和辐射利用效率沿着增加的谷物数量。然而，所有仍然携带许多有害的等位基因源库traits.We进行了广泛的表型的源和库相关的性状在不同的环境和管理方案在一个大面板的历史冬小麦品种。这使我们能够确定现代品种增强源强度，促进高水和氮的吸收效率，高生物量潜力和/或高辐射拦截/利用效率，或具有显着的库强度主要是由每单位面积的大量谷物。然而，这些假定的生理优势并不总是导致谷物产量增加：相反，这些基因型往往表现出库赤字方面的不规则的粮食形成，时空变异的粮食发展，在一揽子提案“小麦源-汇关系和限制”中，（WheatSouSi）”的目的是生成详细的数据，描述在不同环境约束下生长的遗传多样性冬小麦品种的主茎和次级分蘖上的籽粒数量和籽粒大小与轴行数的空间分布，并将这一信息与其他分项目收集的其他全面的源-汇数据集进行比较。我们还将分析茎可溶性碳水化合物，花粉生活力，结实和粒重之间的关系，在空间背景下沿着穗长，在不同的环境约束。该数据将用于评估在最佳与胁迫条件下与茎可溶性碳水化合物的可用性相关的生育力和生殖力的关键基因的不同等位基因组合的益处和权衡。最后，我们将与合作子项目进行联合分析，以调查在不同的发展时间点的非生物胁迫反应，实现茎碳水化合物数据到源库模型，并评估等位基因的变化与谷物产量作为育种的结果下共同选择的性状。总的来说，这些全面的联合分析将提供新的见解的影响，遗传增益的粮食产量的源库关系在现代小麦。

Wheat is one of the most important staple food crops and high grain yields are essential for global food security. In extensive previous work we confirmed that limitations to wheat yield potential are primarily determined by traits implicated in source-sink relations: Modern cultivars show increases in biomass, nutrient use efficiency, harvest index, light interception and radiation utilisation efficiency along with an elevated grain number. However, all still carry many detrimental alleles for source-sink traits.We performed extensive phenotyping of source- and sink-related traits under diverse environmental and management scenarios in a large panel of historical winter wheat cultivars. This enabled us to identify modern cultivars with enhanced source strength, facilitated by high water and nitrogen uptake efficiency, high biomass potential and/or high radiation interception/use efficiency, or with remarkable sink strength imparted mainly by a high number of grains per unit area. However, these putative physiological advantages did not always result in increased grain yield: Instead, such genotypes often showed sink deficits in terms of irregular grain formation, spatio-temporal variability for grain development, or other source-sink tradeoffs.The aim of this subproject in the Package Proposal “Wheat source-sink relationships and limitations (WheatSouSi)” is to generate detailed data describing the spatial distribution of grain number and grain size in relation to rachis row number on main stems and secondary tillers of genetically diverse winter wheat cultivars, grown under different environmental constraints, and compare this information with other comprehensive source-sink datasets collected in other subprojects. We will also analyze the relationships between stem soluble carbohydrates, pollen viability, grain set and grain weight, in a spatial context along the length of the spike, under different environmental constraints. This data will be used to evaluate benefits and trade-offs of different allelic combinations of key genes involved in fertility and fecundity in relation to the availability of stem soluble carbohydrates under optimal vs. stress conditions. Finally, we will perform joint analyses with cooperating subprojects to investigate abiotic stress responses at different developmental timeponts, to implement stem carbohydrate data into source-sink models, and to evaluate allelic shifts related to traits under co-selection with grain yield as a consequence of breeding. Collectively, these comprehensive joint analyses will give novel insight into the impact of genetic gain for grain yield on source-sink relationships in modern wheat.