Wingler Astrid, Soualiou Soualihou
School of Biological, Earth & Environmental Sciences and Environmental Research Institute, University College Cork, Distillery Fields, North Mall, Cork T23 TK30, Ireland.
J Exp Bot. 2025 Jul 2;76(10):2646-2658. doi: 10.1093/jxb/eraf110.
Early flowering of annual plants can lead to resource limitation owing to reduced uptake of nitrogen during the reproductive phase and declining foliar photosynthesis as a result of monocarpic senescence. Low availability of accumulated resources can therefore result in a trade-off between early flowering and reproductive fitness. However, green inflorescence organs (such as siliques, pods, bracts, or awns) can make considerable contributions to photosynthetic carbon gain, and in some cases provide more carbon to seed formation than the leaves. Inflorescence photosynthesis may thereby overcome the flowering time trade-off. In addition to providing photosynthates, inflorescence organs can contribute to seed nitrogen through senescence-dependent nitrogen recycling. In annual crops, breeding has resulted in increased carbon allocation to the grain and higher harvest index, but in some cases this had led to reduced grain protein content. We discuss different breeding targets to address carbon and nitrogen limitation, dependent on the climatic environment. For environments that are prone to drought, we propose a combination of early flowering with enhanced inflorescence photosynthesis or, alternatively, delayed senescence (stay-green) associated with improved water balance. For optimized yield and grain protein content under favourable conditions, enhanced sink strength and extended nitrogen uptake are suggested as breeding targets.
一年生植物的早花会导致资源限制，这是因为生殖阶段氮素吸收减少以及单花衰老导致叶片光合作用下降。因此，积累资源的低可用性可能导致早花与生殖适合度之间的权衡。然而，绿色的花序器官（如角果、豆荚、苞片或芒）对光合碳积累有很大贡献，在某些情况下，为种子形成提供的碳比叶片更多。花序光合作用可能由此克服开花时间的权衡。除了提供光合产物外，花序器官还可以通过依赖衰老的氮循环为种子提供氮。在一年生作物中，育种已导致更多的碳分配到籽粒中，收获指数提高，但在某些情况下，这导致籽粒蛋白质含量降低。我们讨论了根据气候环境来应对碳和氮限制的不同育种目标。对于易干旱的环境，我们建议将早花与增强的花序光合作用相结合，或者与改善水分平衡相关的延迟衰老（持绿）相结合。为了在有利条件下实现最佳产量和籽粒蛋白质含量，建议将增强库强度和延长氮素吸收作为育种目标。
