三种稻飞虱应对水稻病毒感染的免疫应答网络比较分析

The rice planthoppers that include Nilaparvata lugens, Laodelphgax striatellus and Sogatella furciferas are the most destructive pests for rice throughout Asia, which has caused severe rice damage through sucking rice phloem sap and transmitting plant viruses. However,the mechanisms how these planthoppers acquire and transmit the rice virus are not clear yet. Recently, we completed the sequencing and assembly of the N.lugens genomes and the transcriptome sequencing of three rice planthopper species. Based on these data,in this study, we will perform the gene expression profile sequencing of three rice planthoppers responded to rice ragged stunt virus(RRSV)-, rice stripe virus(RSV)- and southern rice black streaked dwarf virus(SRBSDV)-infections, to reveal the host immune responses to the RRSV, RSV and SRBSDV infections, via identifying the differentially expressed immune-related genes and confirming their molecular functions during the viral infection processes. The analysis of the immune-related genes is an important step in determining the overall architecture and functional network of the immune responses to the viral infections in the rice planthoppers. The result will facilitate the understanding of the host immune functions in the rice virus-acquisition and virus-transmission mechanisms, and provide a basis for the further studies on the planthopper disaster mechanisms and its control from the point view of the host immune mechanisms.

稻飞虱是危害我国水稻生产最严重的生物灾害。近年来由褐飞虱传播的水稻齿叶矮缩病、灰飞虱传播的条纹叶枯病和白背飞虱传播的南方黑条矮缩病在我国南方稻区发生范围持续扩大，给我国的水稻作物安全带来了很大的威胁，但由于对传毒机制知之甚少而导致缺乏有效的防治措施。因此，揭示三种稻飞虱传播水稻病毒病的分子机制是当前亟待解决的科学问题。最近我们分别完成了褐飞虱全基因组测序和组装以及三种稻飞虱的转录组测序，本项目拟在此基础上，全面研究褐飞虱、灰飞虱和白背飞虱应对水稻齿叶矮缩病毒、条纹叶枯病毒和南方黑条矮缩病毒感染的免疫应答机制，通过表达谱测序分析揭示三种稻飞虱对特异性及非特异性病毒感染的免疫反应，发现显著差异表达的宿主免疫因子并进行基因功能验证，明确稻飞虱种间及种内个体的获毒传毒特异性与稻飞虱免疫调控机制之间的关系，为揭示稻飞虱成灾机理和对病毒病的防治提供研究基础。

本课题围绕三种水稻病毒即齿叶矮缩病毒、条纹叶枯病毒和南方黑条矮缩病毒分别感染褐飞虱、灰飞虱以及白背飞虱，在昆虫宿主水平进行了比较表达谱测序分析。研究结果揭示了三种稻飞虱在针对特异性病毒感染时，昆虫宿主免疫相关基因的表达存在显著差异，表明昆虫介体在应对特异性植物病毒感染时的免疫应答反应具有昆虫物种特异性。对于取食植物汁液的刺吸式口器昆虫来说，唾液腺是植物病毒复制增殖与传播的重要组织。本课题主要针对感染与未感染齿叶矮缩病毒的褐飞虱唾液腺进行了RNA-Seq分析；同时对感染与未感染齿叶矮缩病毒的褐飞虱分泌的水状唾液进行了Shotgun蛋白质谱分析，对唾液蛋白进行了较为系统的成分鉴定、比较分析与功能研究。本课题进一步研究发现齿叶矮缩病毒感染褐飞虱后明显诱导了唾液腺细胞凋亡，通过RNAi实验明确了齿叶矮缩病毒诱导唾液腺细胞凋亡的信号传导通路; 抑制细胞凋亡通路的基因表达能够显著降低齿叶矮缩病毒从其昆虫介体褐飞虱到植物寄主水稻的传播效率。此外，本课题还揭示了齿叶矮缩病毒与褐飞虱之间的蛋白互作关系，证明了褐飞虱的一个线粒体蛋白在齿叶矮缩病毒的复制增殖过程中具有重要作用。这些研究结果为水稻病毒病的生物防治提供了重要的分子靶标。