水稻萜类代谢物对褐飞虱的间接和直接防御作用研究

The brown planthopper(BPH) is one of the most destructive pests of rice. For rice crops, growing resistant rice varieties is the most effective and friendly way to control BPH. However, how rice plants defend against BPH is still poorly understood which made breeding resistant rice varieties progress slowly. Ample evidence has accumulated in the last few years indicating that plant terpenoids involve in defense against insects.Terpenoids are the most large category of plant secondary metabolites falling into three major groups: monoterpenes,sesquiterpenes and diterpenes. Monoterpenes and the most of sesquiterpenes are usually the majority of plant volatiles, and they release after insect feeding and function in indirect plant defense by attracting predators and/or parasitoids that are natural enemies of feeding herbivores. Diterpenes and a small amount of sesquiterpenes play direct defense by antibiosis mechanism affecting the growth, development and reproduction of feeding herbivores. We found that terpenoid biosynthetic pathways showed different responses to BPH attack in resistant and susceptible rice varieties. We are convinced that the differences in the content and constituent of terpenoids between resistant and susceptible rice plants in response to BPH attack is the important mechanism of rice varieties resistance. This project focuses on studying both the indirect and direct defense against BPH in rice plants by applying resistant and susceptible near isogenic lines. It is hoped that which terpenoids play defense roles and what roles they play in BPH response could be explained. It is also hoped that several terpene synthases which are response for synthetizing different terpenoids between resistant and susceptible rice plants could be identified. With the help of above research results, novel BPH control strategy could be put out and breeding resistant rice varieties could be promoted quickly.

褐飞虱是水稻的主要害虫之一，种植抗褐飞虱的水稻品种是防治褐飞虱最有效和最环保的策略。水稻抗褐飞虱的机理至今未得到很好的阐明，导致抗虫育种工作进展缓慢。萜类代谢物参与植物对虫害的防御应答。萜类主要包括单萜、倍半萜和二萜。单萜和大多数倍半萜是植物挥发物的主要成分，它们引诱昆虫的捕食者或者寄生虫，在植物对虫害的防御应答中起间接防御作用，而二萜和小部分倍半萜则对昆虫具有抗生性，起直接防御作用。我们发现在褐飞虱取食诱导下，萜类生物合成途径在抗感水稻品种中出现了不同的表达模式。我们认为抗感水稻品种受褐飞虱取食诱导后萜类代谢物的含量和组成差异是导致不同的水稻品种对褐飞虱的抗性差异的重要机制之一。本课题拟围绕近等基因系的抗感水稻品种中萜类代谢物和相应的萜类合成酶基因对褐飞虱的间接和直接防御作用展开研究，以期阐明水稻中萜类代谢物对褐飞虱的抗性机理，为褐飞虱的防治提供新的策略，同时推动抗虫育种工作前进。

水稻和小麦是我国最主要的粮食作物，病虫害和逆境是导致粮食减产的重要因素。褐飞虱是水稻最主要的害虫之一，但是水稻抗褐飞虱的机理至今不清楚。有研究表明植物的次生代谢产物参与对虫害的防御应答。我们主要研究莽草酸代谢途径的芳香羧酸和萜类代谢物。此外，由于褐飞虱的复杂性，目前的研究主要集中在水稻层面，很少关注褐飞虱自身，但这却是非常重要的。本课题拟围绕褐飞虱取食近等基因系的抗感水稻品种后水稻的次生代谢物和褐飞虱自身的代谢展开研究，以期阐明水稻抗褐飞虱的机制，为褐飞虱的防治提供新的策略，同时推动抗虫育种工作前进。 穗发芽是影响小麦产量和品质的重要因素，如何控制成熟期穗发芽已成为当前小麦品种改良的重大课题。研究发表转入反义硫氧还蛋白s基因（anti-trx-s）可以抑制成熟期穗发芽，但是具体的机制并不清楚。.主要研究内容和重要结果有以下几个方面：.1，通过LC-MS分析了经褐飞虱取食后，抗感水稻的莽草酸途径的次生代谢物的变化规律。研究结果表明经褐飞虱取食后，抗性水稻的奎宁酸、莽草酸和苯甲酸显著上调；感性水稻的阿魏酸和水杨酸显著下调。我们推测这5个次生代谢产物与水稻抗褐飞虱密切相关。.2，通过荧光实时定量PCR分析了抗性水稻中二萜类植保素生物合成途径中的6个相关基因的表达水平。研究结果表明经褐飞虱取食后，抗性水稻品种上述6个基因的表达水平除了OSKSL7外均有先升高后降低的趋势。我们推测前期升高是为了合成更多的对褐飞虱有伤害的代谢物，后期降低也许是此时已不需要合成此类物质，需把能量和物质更多地用于生长，因此此条途径的代谢流下降。.3，通过NMR和GC-MS分析了褐飞虱取食抗感水稻后自身的代谢差异。主要是研究褐飞虱的核苷酸、有机酸、氨基酸、糖和脂肪酸等。研究结果表明：取食早期，抗性水稻上虫子核苷酸、有机酸、氨基酸、糖和脂肪酸含量普遍低于感性水稻，推测虫子在抗性水稻上吃的少；取食晚期，情况相反。长时间取食抗性水稻导致褐飞虱机体代谢全部受损，最后导致了褐飞虱死亡。.4，通过NMR和GC-MS分析了转基因（含anti-trx-s基因）和野生型小麦种子在发育不同时期的代谢差异。研究结果表明：种子成熟期，anti-trx-s降低了整体代谢，抑制穗发芽；后熟期， anti-trx-s活化了整体代谢，恢复种子发芽能力。.以上研究结果为植物的抗逆抗病提供了很好的基础数据，为育种提供了一定的理论支撑。