动态光环境下盐胁迫对番茄非光化学淬灭(NPQ)弛豫特性的影响机制

设施蔬菜栽培通常因过度施肥导致土壤盐渍化问题突出，同时，自然光下植物长期经受光强动态变化，二者共同影响设施作物生产。在动态光下，以非光化学淬灭（NPQ）为核心的光保护机制是光合作用的必要保障，但由于强-弱光转化下NPQ下调（弛豫）速率远滞后于光强变化速率，大大降低光能利用率。前期研究发现盐胁迫加速了番茄叶片NPQ弛豫速率，说明盐胁迫下植物可能通过加速NPQ弛豫尽可能减少光能利用率的损失，但具体调控机制尚不清楚。本项目拟以番茄野生植株与NPQ弛豫关键蛋白（ZEP与KEA3）过表达和基因突变植株为对象，首先量化不同光强变化下NPQ弛豫对盐胁迫的响应；再次，研究盐胁迫下跨类囊体膜质子推动力及叶黄素循环对NPQ弛豫的影响；最后，研究ZEP与KEA3表达水平在盐胁迫调控NPQ弛豫中的作用从而明确其调控机制。本研究有助于准确反映设施条件下盐胁迫作物的光合生理过程，为培育高光效作物品种提供新的理论基础。

Soil salinity usually occurs in protected horticulture due to overfertilization. Meanwhile, plants usually experience variations in light intensity under natural light. Soil salinity, together with dynamic light, affects crop production in protected horticulture. Under dynamic light, photoprotection is necessary for the normal operation in photosynthesis, where non-photochemical quenching (NPQ) is a key process. However, NPQ relaxation rate from high to low light transition is rather slower than the light decrease rate, which largely decreases light use efficiency. The applicant found salt stress could enhance NPQ relaxation rate in tomato leaves, suggesting salt-stressed plant might perform a faster NPQ relaxation to mitigate the loss in light use efficiency, but the mechanism is rather unclear. Therefore, in this project, we will use tomato wildtype, transgetic over-expression lines and mutants of key proteins on regulating NPQ dynamics (ZEP and KEA3) as the subjects: firstly, we will analyze NPQ relaxation under a diverse of dynamic light regimes in salt-stressed and non-stressed plants; Secondly, we will investigate how transmembrane proton gradient and xanthophyll cycle affect NPQ relaxation under salt stress. Thirdly, we will investigate the role of ZEP and KEA3 expression levels in salt-regulated NPQ relaxation to verify the mechanism. This project would be important to accurately estimate photosynthetic processes of salt-stressed crops in protected horticulture and to provide a new theoretical basis for optimizing crop varieties with higher light use efficiency.