大麦条纹花叶病毒(BSMV) 不同的分离物存在明显的寄主范围差异，ND18分离物不侵染玉米自交系B73，而Norwich、北京和新疆分离物可以系统侵染B73。本申请课题拟利用已有的BSMV ND18分离物和Norwich分离物的侵染性cDNA克隆，通过不同RNA组分 （alpha、beta和gamma）的重配、同一组分不同片段的重组以及对差异氨基酸的定点突变，精确定位BSMV病毒基因组上对玉米自交系B73的致病决定因子及其关键氨基酸；分析BSMV对玉米致病决定因子是否存在蛋白质的翻译后修饰（磷酸化等），并通过实验验证翻译后修饰对BSMV侵染性的影响；利用酵母双杂交等方法，从玉米自交系B73 的cDNA文库中筛选与致病决定因子互作的玉米蛋白，并分析其在病毒侵染和胞间移动中的作用，为深入理解BSMV与玉米互作的分子机理提供新的科学证据。

Barley stripe mosaic virus (BSMV) North Dakota 18 (ND18), Norwich (NW), Beijing (BJ) and Xinjiang (XJ) isolates elicit different phenotypic responses on maize inbred lines B73. The ND18, BJ and XJ strains are unable to infect the inbred line B73 and produce no visible symptoms or virus, whereas the NW, XJ and BJ strains are virulent and results in an intense mosaic and stripe phenotypes accompanied by large amounts of virus. In this proposal, based on the infectious cDNA clones of BSMV ND18 and NW isolates, we tried to precisely mapping the pathogenicity determinant and its key amino acids to maize inbred line B73 in the genome of BSMV through the reassortment of different RNA components (alpha、beta and gamma) recombination of different fragments in the same RNA component, as well as site-directed mutation of specific amino acids. The characterization of the viral pathogenicity determinant will be analyzed through biochemical analysis to see whether it could be subject to post-translational modification (eg. phosphorylation), and the effect of the modification of viral protein on the infectivity of BSMV will be further validated. Using yeast two hybridization and so on, maize proteins that interact with the viral pathogenicity determinant will be screened from the cDNA library of maize inbred line B73, followed by analyzing its function during the infection and cell-to-cell movement of BSMV, thus providing new scientific evidence for further understanding the molecular mechanisms involved in BSMV-maize interaction.