油菜素内酯（BR）调控马缨杜鹃适应干旱的机理研究

Rhododendron is one of the most famous ornamental plants in the world. However, the drought stress caused by water shortage is a key factor limiting its cultivation and application. Understanding the adaptive mechanism of Rhododendron to drought is important for the breeding new variety with drought resistance and commercial cultivation. As a kind of stress hormone, brassinosteroids (BR) can regulate the drought tolerance of plant. We have found that the genes related to BR metabolic pathways were enriched by transcriptome sequencing, and exogenous BR can increase drought resistance. However, it is unclear how BR regulates the adaptation of R. delavayi to drought. Based on this situation, this project will analyze the effect of exogenous BR on photosynthetic capacity, antioxidant system, and active oxygen content to investigate the physiological mechanism of BR regulating the response of Rhododendron to drought. Further, the change of protein drought will be analyzed by iTRAQ technology, the relation between BR related protein and gene expression were compared, and BR metabolism key genes associated with drought will be targeted screening. On this base, we will construct the silencing and excessive expression plant by transgenic technology, and validate the function of BR metabolism key genes in the response of R. delavayi to drought. The results can explore the regulating mechanism of BR in the adaptation of R. delavayi to drought, and can also provide new genes and proteins for the innovation of germplasm resources in Rhododendron.

杜鹃是世界著名的园林观赏植物，干旱严重制约着杜鹃的栽培及应用。研究杜鹃适应干旱的机理对其抗旱育种和栽培具有重要意义。油菜素内酯（BR）作为一种逆境缓和激素，可调控植物的耐旱性。申请者前期研究发现，BR代谢相关基因在马缨杜鹃的干旱应答过程中高度富集，但BR在其干旱适应中的作用及调控机制尚不清楚。本项目从外源BR对马缨杜鹃耐旱性的生理研究入手，分析外源BR对干旱胁迫下马缨杜鹃光合能力、抗氧化系统、活性氧含量等的影响；进一步，利用iTRAQ技术分析干旱胁迫下外源BR处理的蛋白表达变化，重点对BR代谢相关响应蛋白与基因表达进行关联分析，靶向筛选得到与耐旱性密切相关的BR代谢关键基因；在此基础上，利用转基因技术，使BR代谢关键基因在马缨杜鹃中沉默或超量表达，验证BR代谢关键基因在马缨杜鹃干旱适应中的功能。研究结果可以明确BR在马缨杜鹃耐旱性中的调控作用，并为杜鹃的种质资源创新提供新蛋白、新基因。

杜鹃是世界著名的园林观赏植物，干旱严重制约着杜鹃的栽培及应用。油菜素内酯（BR）作为一种逆境缓和激素，可调控植物的耐旱性。项目以耐旱性较强的马缨杜鹃为材料，通过外源喷施BR，分析BR调控马缨杜鹃适应干旱的生理机制及蛋白表达特征。研究结果表明：1、外源喷施BR能够增加干旱胁迫下马缨杜鹃叶片的气孔导度，提高光饱和点和光能利用范围，具有较高的光能利用效率，改善干旱胁迫下马缨杜鹃的光合特性；2、外源BR可以减轻干旱胁迫对膜脂产生的过氧化伤害，使马缨杜鹃保持较好的水分状态，减轻干旱胁迫的不利影响；3、利用数据独立采集（DIA）蛋白组学方法，共鉴定出 3453个蛋白，其中683个为差异表达蛋白（DEPs）。BR处理中独特表达的DEPs主要参与了“核糖体”、“醚脂代谢”、“光合作用”和“氧化磷酸化”等途径。BR处理主要通过保持核糖体复合物的完整性和稳定性以调节蛋白质合成，维持干旱胁迫下能量代谢和碳代谢之间的平衡来改善马缨杜鹃的耐旱性；4、采用组织培养途径和农杆菌介导的整株感染法进行马缨杜鹃遗传转化体系探索，GUS阳性率分别达到4.5%和25.5 %，为后续开展基因功能验证奠定基础。研究结果补充了杜鹃属植物适应干旱的机理，对杜鹃属植物的遗传改良提供理论基础，且对应用外源调节物质提高杜鹃的耐旱性具有重要的指导作用。发表研究论文6篇，其中SCI收录4篇；申请相关专利1项；培养在职博士研究生2名，硕士研究生1名，项目主持人获“云南省中青年学术和技术带头后备人才”和“云南省青年拔尖人才”称号。