谷胱甘肽还原酶(GR)基因在硒处理延缓菜心采后黄化中对叶绿体H2O2的调节作用

菜心(Tsai-Tai)是我国南方的重要蔬菜之一。由于菜心采后极易衰老黄化，严重影响了其品质及远程销售。申请人研究表明，菜心黄化与叶片过氧化氢（H2O2）的含量密切相关，而硒处理减少了H2O2积累并延缓了菜心采后衰老。AsA-GSH循环是叶绿体清除H2O2的重要途径，谷胱甘肽还原酶(GR)是该途径中的关键酶。申请人推测：硒上调了叶绿体GR基因的转录水平和酶活性，增强了叶片调节H2O2的能力，从而延缓了菜心的衰老黄化。但硒对叶绿体GR基因是否具有调控作用尚未见报道。鉴于此，本项目拟分析硒对GR基因表达的影响及其与采后菜心叶绿体H2O2调控的关系；并通过遗传转化手段，验证GR基因在H2O2介导的细胞衰老凋亡中对叶绿体结构稳定性及细胞活力的影响。最终阐明GR基因在硒处理延缓菜心采后黄化中对H2O2的调控作用。本项目有望揭示硒调控菜心采后黄化的新机制，加深人们对硒调控叶菜衰老黄化机理的认识。

Tsai-Tai is one of the most important leafy vegetables in South China. Yellowing is the main cause of its postharvest lost. Our previous research showed that hydrogen peroxide was one of the most critical factors inducing leaf yellowing. However, pretreatment with selenium(Se) significantly reduced the levels of hydrogen peroxide and decreased the yellowing index. Researches have shown that AsA-GSH cycle was one of the most important pathways for free radical scavenging in chloroplast. Glutathione Reductase (GR) was the key element in AsA-GSH cycle. We suppose that selenium up-regulated GR expression, and reduced hydrogen peroxide in chloroplast. However, the mechanisms of selenium in regulating the GR gene is still unclear. This project aims to analyze the effects of Se on GR expression in relation to chloroplast H2O2 in harvested Tsai Tai; Moreover, through the approach of genetic manipulation, clarify the effect of GR gene on cell apoptosis mediated by H2O2 and on chloroplast stability and cell vitality of leaves of Tsai Tai. This study will provide evidences for the mechanisms of regulation of selenium on senescence of leafy vegetables.