甘蔗花叶病毒调控玉米蛋白ZmPDIL1-1和ZmPDRP表达水平的生物学意义

Regulation of host factors by virus is a key issue in virus-host interactions. Our previous work found that the expression levels of maize Protein Disulfide Isomerase (ZmPDIL1-1) and Pyruvate, Pi Dikinase Regulatory Protein (ZmPDRP) were significantly changed upon either Sugarcane mosaic virus (SCMV) or Pennisetum mosaic virus (PenMV) infection that induces maize dwarf mosaic disease. With SCMV-maize interaction as a research system, preliminary results showed that knockdown of ZmPDIL1-1 significantly decreased the levels of SCMV replication and multiplication, and downregulation of ZmPDRP significantly decreased the phosphorylation level of pyruvate orthophosphate dikinase (ZmPPDK), which could cause photosynthesis disturbance. This proposal is concentrated on the following two scientific questions. One is how SCMV regulates the expression levels of ZmPDIL1-1 and/or ZmPDRP. Another is what significance of the regulation on SCMV-maize interaction. This proposal focuses on the regulation of host proteins by viruse that cause important disease. The research results will provide vital data to dissect the mechanism of regulating host proteins by virus, and will produce novel idea for research on virus-host interaction and developing new strategies for virus control.

病毒对寄主因子的调控是病毒—寄主互作中的一个关键问题。前期实验发现,甘蔗花叶病毒（SCMV）或白草花叶病毒（PenMV）在侵染玉米引起矮花叶病的过程中均显著改变了玉米蛋白质二硫键异构酶（ZmPDIL1-1）和丙酮酸磷酸双激酶调控蛋白（ZmPDRP）表达水平。以SCMV—玉米互作为主要研究系统，瞬时沉默ZmPDIL1-1显著降低了SCMV复制增殖水平，而ZmPDRP的下调显著降低了C4光合途径限速酶——丙酮酸磷酸双激酶的磷酸化水平，导致光合作用紊乱。鉴于此，本项目围绕2个关键科学问题：一、SCMV在侵染过程中如何调控ZmPDIL1-1和ZmPDRP表达？二、这种调控对SCMV—玉米互作具有什么生物学意义？本项目聚焦重要病害发生过程中病毒对寄主蛋白的调控，研究结果将为揭示病毒调控寄主蛋白表达的机制及其在病毒致病中的功能提供重要数据，为研究病毒—寄主互作和发展抗病毒新策略提供新思路。

病毒调控寄主因子用于自身侵染，并影响寄主代谢等生理过程。为深入研究甘蔗花叶病毒（SCMV）对玉米的致病性，本项目测定了SCMV侵染玉米过程中调控 ZmPDIL1-1 和 ZmPDRP 表达的时间进程，确定了调控ZmPDRP下调的的关键时间点为初步显症期和症状稳定期；明确了SCMV 编码的蛋白及基因组非编码区不能直接调控ZmPDIL1-1 和 ZmPDRP 表达水平，同时鉴定 SCMV 编码的CI蛋白与 ZmPDRP 直接互作；通过基因沉默、基因过表达、基因编辑介导的敲除，明确了ZmPDIL1-1 和ZmPDRP均具有促进 SCMV 增殖、侵染的作用；测定了SCMV侵染增殖过程中对玉米叶片光合速率、CO2固定、ZmPDRP积累、ZmPPDK磷酸化水平和活性、PEP积累水平的调控和影响，表明SCMV侵染在症状出现前阶段增加PPDK的活性，在症状出现后阶段降低了PPDK的活性。发现了SCMV复制位点位于内质网、高尔基体、线粒体和过氧化物酶体。这些结果明确了玉米蛋白ZmPDIL1-1 和 ZmPDRP在SCMV侵染中的生物学意义，为研究防控SCMV的新策略和培育抗病毒玉米新材料提供了重要依据。