玉米光合作用动态适应及其与发育适应互作的机制研究

Photosynthetic acclimation to light environment has great influences on crop growth and yield. In past decades, extensive studies have been focused on the developmental acclimation of photosynthesis under static light environments. Actually, in the field, crops often grow in environments where the light fluctuates dramatically and frequently. Therefore, to fully understand the mechanisms of photosynthetic acclimation to light environments, fluctuating light has to be considered with care. Recently, more and more attention has been paid to the dynamic acclimation of photosynthesis, which is suggested to play a very important role in coping with fluctuating light. However, the regulatory mechanisms of dynamic acclimation and its interaction with developmental accliamtion have not been fully understood. To clarify these questions, careful investigations will be carried out with maize. Firstly, the mechanisms of dynamic acclimation will be extensively explored with mature leaves under fluctuating light. Secondly, the effects of fluctuating light on developmental acclimation in young leaves will be carefully studied; thereafter, the focus will be on the interaction between developmental acclimation and dynamic acclimation, thereby to elucidate the key mechanisms of photosynthetic acclimation to fluctuating light. On that basis, the changes of dynamic and developmental acclimation will be studied via simulating the natural light environment, and the factors influencing photoysnthesis and growth under fluctuating light in the field will also be analysed. In this study, we shall reveal the regulatory network of dynamic acclimation, elucidate the interation mechanisms between developmental acclimation and dynamic acclimation, and construct a system of photosynthesis acclimation. Additionally, our studies will provide new insight into developing culture techniques for high photosynthetic efficiency and variety screening, which will greatly benefit the improvement of crop planting and breeding.

光合作用光适应能力影响作物生长发育，甚至产量。以往的光适应研究主要针对静态光环境强调发育适应。但是，田间光环境经常剧烈、频繁地波动。因此，探讨作物光适应不得不考虑光环境的波动性。虽然光合作用动态适应作为应对波动光的重要策略开始受到关注，但动态适应机制以及其与发育适应的关系尚不清楚。为全面理解作物光适应体系及相关机制，本项目以玉米为材料，研究波动光诱导成熟叶发生动态适应的规律和调控；进而，探讨波动光对新生叶发育适应的影响，以及发育适应与动态适应的相互作用；在此基础上，结合田间光环境监测和模拟，研究田间动态适应和发育适应的变化规律，澄清复杂光环境影响玉米碳同化和生长的机制。本项目将揭示动态适应调控网络，阐明动态适应和发育适应的相互作用机制，构建光适应调控体系，丰富和发展光合作用理论；同时，理解复杂光环境下光合作用的光适应和调控还将为发展高光效栽培技术、品种光适应评价和定向改良提供新的思路。

光合作用光适应能力影响作物生长发育，甚至产量。以往的光适应研究主要针对静态光环境强调发育适应。但是，田间光环境经常剧烈、频繁地波动。因此，探讨作物光适应不得不考虑光环境的波动性。首先，本项目保持波动光照时间相同改变波动频率，研究玉米和黄瓜不同生理过程对光强波动频率的敏感性差异，阐述动态适应的规律，揭示相关调控机制。其次，改变波动光的强光照光时间，研究新生叶片发育适应响应强光照光时间的规律，阐述发育适应机制，并揭示发育适应与动态适应的关系。在此基础上，研究田间条件下光环境波动对光能利用、光合速率和同化物积累的影响，阐述田间玉米叶片光合作用及适应的规律。我们的结果表明，照光时间相同条件下，波动频率一定程度上加快光合作用诱导，增强光破坏防御机制，但仍然能够较大程度上减少稳态光合作用的时间，降低光合能力和光能利用效率。因此，总的强光照光时间是波动环境影响玉米光合作用的一个重要特征。延长强光照光时间能够增强动态适应，包括迅速下调植物叶片天线转化效率，增强光系统II实际光化学效率和非光化学猝灭，从而确保光系统II反应中心不被过度还原。另一方面，延长强光照光时间还能够增强叶片发育适应，而发育适应是大幅提高动态适应的一个必要结构条件。此外，基于蛋白组学研究，确定了主要调控位点，构建了蛋白调控网络。田间条件下，适度提高玉米栽培密度能够增强光环境的波动性，但继续提高密度时光环境波动性会降低。无论光环境波动性增强与否，玉米冠层的强光照光时间都与光合能力和生物量呈明显的正相关。因此，田间数据进一步证明波动光环境下强光照光时间是影响玉米光合能力和产量的重要因素，而不是简单的光照强度。本项目揭示了动态适应调控规律，阐明动态适应和发育适应的相互作用机制，构建了复杂光环境下玉米的光适应调控体系，丰富和发展光合作用理论；同时，本研究还为发展高光效栽培技术、品种光适应评价和定向改良提供了新的思路。