干旱胁迫下H_2S信号增强植物叶片的光合作用

H_2S Enhanced Photosynthesis in Response to Drought Stress

干旱胁迫是影响农作物产量最重要的环境因素之一。硫化氢(H_2S)作为第三种气体信号分子在植物体内具有多样且积极的生理功能。目前已了解,H_2S在响应植物干旱胁迫应答以及增强植物光合作用的过程中发挥重要作用,但关于内源性H_2S对干旱胁迫下植物光合作用的调节机制未见报道。该研究以拟南芥哥伦比亚野生型(wild type Col-0,WT)、H_2S产生酶编码基因DES缺失突变体des以及H_2S产生酶编码基因DES过表达突变体OE-DES为实验材料,研究内源性H_2S对干旱胁迫下拟南芥光合作用的调节机制。研究结果显示,植株在正常生长条件下,内源性H_2S促使叶片净光合速率、蒸腾速率、叶绿素含量显著升高;植株遭受干旱胁迫时,内源性H_2S可以显著上调Rubisco和Rubisco活化酶(Rubisco activase,RCA)的表达水平,保护叶绿体结构的完整性,促使叶片净光合速率显著上升,维持叶片相应的蒸腾速率,并且引起叶片气孔关闭和胞间CO_2浓度显著升高。

Drought stress is one of the most serious environmental factors affecting crop yield. It has been known that hydrogen sulfide（H_2S） as the third gas signal molecular, plays a critical physiological role in responding to drought stress and enhancing plant photosynthesis. However, there are few reports about the regulation mechanisms of endogenous H_2S in plant photosynthesis under drought stress. In this study, using Arabidopsis thaliana Columbia-0 wild-type（Col-0, WT）, H_2S-producing enzyme encoding gene DES defective mutants（des） and DES over-expression plant（OE-DES） as experimental materials, we investigated the physiological function and mechanism of endogenous H_2S signal in photosynthesis of A. thaliana under drought stress. The results showed that, under normal growth conditions, endogenous H_2S significantly promoted the increase of net photosynthesis rate, transpiration rate and chlorophyll content in leaves. When the plants were subjected to drought stress, endogenous H_2S could significantly up-regulate the genes expression level of Rubisco and Rubisco activase（RCA）, thus protect the chloroplast structure, promote the significant increase of net photosynthesis rate and intercellular CO_2 concentration, induce stomatal closure and maintain the corresponding transpiration rate of leaves.