Lichthardt Carolin, Chen Tsu-Wei, Stahl Andreas, Stützel Hartmut
Vegetable Systems Modelling Section, Institute of Horticultural Production Systems, University of Hannover, Hannover, Germany.
Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Giessen, Germany.
Front Plant Sci. 2020 Feb 7;10:1771. doi: 10.3389/fpls.2019.01771. eCollection 2019.
Optimizing the interplay between sinks and sources is of crucial importance for breeding progress in winter wheat. However, the physiological limitations of yield from source (e.g. green canopy duration, GCD) and sink (e.g. grain number) are still unclear. Furthermore, there is little information on how the source traits have been modified during the breeding history of winter wheat. This study analyzed the breeding progress of sink and source components and their relationships to yield components. Field trials were conducted over three years with 220 cultivars representing the German breeding history of the past five decades. In addition, genetic associations of QTL for the traits were assessed with genome-wide association studies. Breeding progress mainly resulted from an increase in grain numbers per spike, a sink component, whose variations were largely explained by the photosynthetic activity around anthesis, a source component. Surprisingly, despite significant breeding progress in GCD and other source components, they showed no direct influence on thousand grain weights, indicating that grain filling was not limited by the source strength. Our results suggest that, 1) the potential longevity of the green canopy is predetermined at the time point that the number of grains is fixed; 2) a co-evolution of source and sink strength during the breeding history contribute to the yield formation of the modern cultivars. For future breeding we suggest to choose parental lines with high grain numbers per spike on the sink side, and high photosynthetic activity around anthesis and canopy duration on the source side, and to place emphasis on these traits throughout selection.
优化库与源之间的相互作用对冬小麦育种进展至关重要。然而，源（如绿色冠层持续时间，GCD）和库（如粒数）产量的生理限制仍不清楚。此外，关于冬小麦育种历史中源性状如何改变的信息很少。本研究分析了库和源组分的育种进展及其与产量组分的关系。在三年时间里对代表德国过去五十年育种历史的220个品种进行了田间试验。此外，通过全基因组关联研究评估了这些性状的QTL的遗传关联。育种进展主要源于穗粒数的增加，穗粒数是一个库组分，其变异在很大程度上由开花期周围的光合活性（一个源组分）所解释。令人惊讶的是，尽管在GCD和其他源组分方面取得了显著的育种进展，但它们对千粒重没有直接影响，这表明籽粒灌浆不受源强度的限制。我们的结果表明，1）绿色冠层的潜在寿命在粒数固定的时间点就已预先确定；2）育种历史中源和库强度的共同进化有助于现代品种的产量形成。对于未来的育种，我们建议在库方面选择穗粒数高的亲本系，在源方面选择开花期周围光合活性高和冠层持续时间长的亲本系，并在整个选择过程中强调这些性状。
