硒调控番茄果实成熟衰老的线粒体蛋白质组学研究

Fruit are rich in nutrients and serve as an important component of diet. However, harvested fruit are susceptible to senescence and decay during storage, causing quality deterioration and reduced shelf life. Selenium (Se), an essential element for animals and humans, has also been found to delay plant senescence and plays pivotal roles in protecting plants against abiotic stresses. In this study, plant physiology, biochemistry and proteomics methods are used to investigate the effects of preharvest selenate sprays on postharvest quality, storage, reactive oxygen species metabolism, lipid peroxidation and expression of mitochondrial protein in fruit. Moreover, biological function of differentially expressed protein and the expression of their genes will also be analyzed. Therefore, the proposed work aims to explore possible regulatory mechanism of selenium on fruit ripening and senescence, which is beneficial for promoting fruit quality and resistance.

果实营养丰富，是人类膳食结构中的重要组成部分，但采后果实在贮藏过程中会逐渐衰老变质，果品下降，货架期缩短。硒不仅是动物和人体所必须的一种微量元素，还能延缓植物的衰老，在植物的非生物逆境胁迫中起着重要的作用。本项目利用植物生理学、生物化学和定量蛋白质组学方法，研究采前喷施硒酸盐对采后番茄果实品质、贮藏效果、活性氧代谢、膜脂过氧化以及线粒体蛋白表达的影响，并对鉴定出的差异蛋白进行功能分析和分子水平上的验证，深入探讨硒对果实成熟衰老的调控机制，为提高果实品质和抗性奠定基础。

果实采后腐烂和品质劣变会造成巨大的经济损失。硒是一种重要的微量元素，具有抗氧化特性。本项目研究采前喷施硒酸钠对采后番茄果实抗病性、成熟衰老和营养品质的影响及调控机制。结果发现，1 mg L-1 的硒酸钠能有效控制采后番茄果实灰霉病的发病率，减轻病原菌侵染过程中膜脂过氧化程度，提高果实抗氧化酶的活性和非酶抗氧化剂的含量。采前硒处理能明显延缓果实的成熟衰老，保持果实的品质。硒通过下调乙烯合成途径中关键酶基因的表达，来抑制果实乙烯释放和呼吸速率，通过下调活性氧产生途径中关键酶基因的表达，增强抗氧化酶的活性来提高果实的抗氧化防御系统。另外，硒处理能增加果实中的硒、可溶性糖、氨基酸和活性物质的含量，提高了果实的营养品质。利用iTRAQ定量蛋白质组学技术，分别对对照番茄果实和富硒番茄果实进行蛋白质组定量分析，共鉴定出269个差异表达的蛋白。差异表达的蛋白涉及碳水化合物代谢，氨基酸代谢以及次级代谢。此结果有助于阐明硒提高番茄果实营养品质的机理。本研究所采用的硒处理方法不仅能控制番茄果实采后病害，延缓果实衰老，还可以提高果实的营养品质，为人们补充硒含量，在实际生产中具有较高的应用价值。