Dynamic acclimation of source capacity in fluctuating light and temperature environments

小麦是最重要的粮食作物之一，粮食高产对全球粮食安全至关重要。在过去的一个世纪里，育种不断提高产量，然而，与气候变化相关的挑战和对作物投入的监管限制越来越抑制了产量潜力。我们先前的大量工作证实，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。“小麦源库关系与限制(WheatSouSi)”这一子项目的目的是了解环境波动对冠层源容量的形成、适应和限制的影响。植物不断地适应变化的光和温度环境。驯化是影响光合器官大小和能力的动态生理过程，决定了冬小麦籽粒灌浆的来源能力。虽然利用恒定的光温环境对光合作用的光温适应进行了很好的研究，但我们对光温条件的适应还知之甚少。基于光合作用蛋白质合成速率与光温呈非线性关系的假设，我们首次提出了一个光合作用蛋白质周转的机制模型来描述植物对光温变化的适应。其次，计划在50个冬小麦品种上进行一系列生长室实验，以对所提出的模型进行参数化和验证。不同品种之间的光合作用适应策略的差异可以用模型中的参数来表征。此外，光和温度对叶片水平上气孔形态、光合作用诱导和水分利用效率之间的协调的综合影响将被量化，并被整合到静态和动态功能结构植物模型(FSPM)中，以了解如何通过光合作用适应策略最大化冠层源容量。为了综合所有结果的结果，将使用结构方程模型来系统地检验生理性状、源强、库强和籽粒产量之间的因果相关性的强度和显著性。这些知识的获得将有助于更好地理解作物生理，并改进描述源和库动态的作物模型。

Wheat is one of the most important staple food crops and high grain yields are essential for global food security. Breeding raised yields continuously over the past century, however yield potential is increasingly suppressed by challenges associated with climate change and regulatory restrictions on crop inputs. Our extensive previous work confirmed that limitations to wheat yield potential are primarily determined by traits implicated in source-sink relations. The aim of this subproject in the Package Proposal “Wheat source-sink relationships and limitations (WheatSouSi)” is to understand the effects of environmental fluctuations on the formation, acclimation and limitation of canopy source capacity.Plants constantly acclimatize their photosynthetic capacity to fluctuating light and temperature environments. Acclimations are dynamic physiological processes affecting the size and the capacity of photosynthetic organs, which determine source capacity of winter wheat for grain filling. Although light and temperature acclimation of photosynthesis have been well studied using constant light and temperature environments, our knowledge about the acclimation to fluctuating light and temperature conditions is rare. Based on the hypothesis that synthesis rates of photosynthetic proteins depend non-linearly on light and temperature, we first propose a mechanistic model of photosynthetic protein turnover to describe the acclimation to fluctuating light and temperature. Second, a series of growth chamber experiments are planned to parameterize and to validate the proposed model in 50 winter wheat cultivars. The differences in photosynthetic acclimation strategies between cultivars can be characterized by their parameters in the model. Additionally, the combined effects of light and temperature on the coordination between stomatal morphology, photosynthetic induction and water use efficiency at leaf level will be quantified and integrated into static and dynamic functional-structural plant models (FSPMs) to understand how canopy source capacity can be maximized by photosynthetic acclimation strategies. To synthesize the outcomes of all results, structural equation modelling will be used to systematically test the strength and significance of causal interdependencies between physiological traits, source strength, sink strength and grain yield. The knowledge gain will facilitate a better understanding of crop physiology and improve crop models describing source and sink dynamics.