Drought is a major cause of losses in crop yield. Under field conditions, plants exposed to drought are usually also experiencing rapid changes in light intensity. Accordingly, plants need to acclimate to both, drought and light stress. Two crucial mechanisms in plant acclimation to changes in light conditions comprise thylakoid protein phosphorylation and dissipation of light energy as heat by non‐photochemical quenching (NPQ). Here, we analyzed the acclimation efficacy of two different wheat varieties, by applying fluctuating light for analysis of plants, which had been subjected to a slowly developing drought stress as it usually occurs in the field. This novel approach allowed us to distinguish four drought phases, which are critical for grain yield, and to discover acclimatory responses which are independent of photodamage. In short‐term, under fluctuating light, the slowdown of NPQ relaxation adjusts the photosynthetic activity to the reduced metabolic capacity. In long‐term, the photosynthetic machinery acquires a drought‐specific configuration by changing the PSII‐LHCII phosphorylation pattern together with protein stoichiometry. Therefore, the fine‐tuning of NPQ relaxation and PSII‐LHCII phosphorylation pattern represent promising traits for future crop breeding strategies.

中文翻译：

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调节小麦光合活性对干旱和光照波动的影响。

干旱是造成农作物减产的主要原因。在田间条件下，暴露于干旱的植物通常也会经历光强度的快速变化。因此，植物需要适应干旱和轻度胁迫。植物适应光照条件变化的两个关键机制包括类囊体蛋白磷酸化和通过非光化学猝灭（NPQ）的热量散发的光能。在这里，我们通过使用波动光对植物进行了分析，分析了两个不同小麦品种的适应能力，该植物经受了田间通常发生的缓慢发展的干旱胁迫。这种新颖的方法使我们能够区分出四个干旱阶段，这对于谷物的产量至关重要，并且可以发现与光害无关的适应性响应。在短期内，在波动的光线下，NPQ松弛的减慢将光合作用的活性调节为降低的代谢能力。从长远来看，光合作用机制通过改变PSII-LHCII的磷酸化模式以及蛋白质化学计量来获得针对干旱的配置。因此，NPQ弛豫和PSII-LHCII磷酸化模式的微调代表了未来作物育种策略的良好前景。