番茄褪绿病毒编码的小分子P6蛋白抑制寄主转录水平基因沉默抗性的分子机制研究

DNA甲基化途径介导的转录水平基因沉默，参与调控高等生物的多种重要的代谢途径。 DNA病毒抑制宿主/寄主DNA甲基化途径介导的转录水平基因沉默的分子机理研究报道较多。然而，RNA病毒，特别是植物RNA病毒抑制植物DNA甲基化途径介导的转录水平基因沉默抗性的分子机制，尚需进一步深入研究。申请者前期以我国爆发性危害茄科作物的双分体正单链RNA（+ssRNA）病毒--番茄褪绿病毒（Tomato chlorosis virus，ToCV）为对象，研究发现ToCV编码的小分子P6蛋白，抑制本氏烟DNA水平甲基化途径。在此基础上，系统研究ToCV编码的小分子P6蛋白，识别的寄主DNA甲基化途径关键靶标蛋白及其互作分子机制，寄主DNA甲基化途径靶标蛋白调控的转录水平基因沉默抗性分子机制。揭示+ssRNA植物病毒，调控寄主DNA甲基化途径介导的转录水平基因沉默抗性的分子机制。

The pathway transcriptional gene silencing (TGS) mediated by DNA methylaiton, was involving in multiple metabolic pathways of eukaryotes. The mechanisms of DNA viruses inhibiting hosts DNA methylation mediated TGS were well documented. However, it was unclear of RNA viruses, especially plant RNA viruses, inhibiting hosts DNA methylation mediated TGS. The preliminary study suggests the low molecular P6 protein of positive strand RNA plant virus--Tomato chlorosis virus, which severe epidemic in Solanaceae crops, possesses the capacity to inhibiting the DNA methylation of Nicotiana benthamiana. This project would systematically uncover the ToCV P6 protein recognized host protein(s) involving in host DNA methylation and its recognizing mechanism, the molecular mechanism of host protein(s) regulating the host TGS resistance. The results would scientifically contribute to reveal the molecular mechanism of regulating host DNA methylation mediated TGS resistance by +ssRNA plant viruses.