马铃薯纺锤块茎类病毒基因变异分离株致病力差异及其与寄主互作分子机制的研究

Potato spindle tuber viroid (PSTVd),as a main potato disease pathogen, impacts seriously on potato yield and quality. PSTVd is currently the most important viroid pathogen with world-wide distribution. According to the pathogenicity, PSTVd can be divided into severe, mild and intermediate strains. Mild strain usually causes 30% yield losses, while the yield losses can research 60% for severe strain. We have observed that potato plants infected by PSTVd isolates with different pathogenicity developed different disease symptoms in the tubers and plants. However, the molecular mechanism of this phenomenon has not been investigated. This project aims to analyze the secondary structure of different virulence PSTVd sequences and PSTYd-generated small RNAs (srPSTVds), as well as alignment analysis of srPSTVds with potato genome to identify srPSTVds targeted area of potato genome. By means of bioinformatics and biological experimental analyses, we will illustrate the molecular mechanism and effect of interaction between the srPSTVds and host targets on different pathogenicities. At the same time, we will try to establish the defense strategy resistent PSTVd by positively regulating the endogenous gene in potato. The study will provide very important theory evidences and practical application value in revealing the pathogenic mechanism of PSTVd, also providing an important scientific basis for finding an effective way to prevent PSTVd disease.

马铃薯纺锤块茎类病毒（Potato spindle tuber viroid, PSTVd）是影响马铃薯产量和质量的主要病害。我们前期研究发现，不同致病力的PSTVd在侵染马铃薯后，引发马铃薯产生不同症状。但迄今为止，针对PSTVd不同基因变异分离株，产生不同致病力这一现象的分子机制尚无科学解释。本项目拟对不同致病力PSTVd的二级结构分析为切入点，分析比较不同基因变异分离株产生小RNA（srPSTVds）的种类及数量，与马铃薯基因组进行分析比对，通过生物信息学和生物试验方法，明确不同变异株产生srPSTVds在马铃薯基因组中的靶向区域差异，研究srPSTVds与寄主的互作关系，从而揭示不同基因变异株产生不同致病力的分子机制，并通过调控马铃薯內源基因来建立应对PSTVd的防御体系。该研究在揭示PSTVd致病机制的同时，对于探寻抗PSTVd有效途径提供重要科学依据，具有重要的理论和应用价值。

本项目主要针对不同致病力PSTVd的致病性差异开展研究，分析比较不同基因变异分离株产生小RNA(srPSTVds)的种类及数量；研究srPSTVds与寄主的作用关系，明确不同变异株侵染马铃薯后转录本的表达差异，从而揭示不同基因变异株产生不同致病力的分子机制；通过调控马铃薯內源基因来建立应对PSTVd的防御体系。本项目的研究结果表明，24nt的小RNA或许是诱导不同致病系PSTVd产生不同致病性的重要因素；差异表达的马铃薯功能基因也是产生不同致病性的重要因素；通过调控马铃薯Brp基因的表达可以有效的提高马铃薯对PSTVd的抗性。