Phytopathology. 1999 Feb;89(2):118-23. doi: 10.1094/PHYTO.1999.89.2.118.
ABSTRACT Tobacco cultivar Virgin A Mutant (VAM) is reported to have the recessive potyvirus resistance gene va. Varied levels of resistance were observed in VAM plants inoculated with Japanese potato virus Y (PVY) isolates. VAM was highly resistant to most of the PVY isolates tested and tolerant to three necrotic strain isolates of PVY-T. Based on data obtained from tissue printing and press blotting, the resistance appeared to be mainly at the level of cell-to-cell movement. PVY replicated in VAM proto-plasts, but the replication was 30% lower than in susceptible tobacco, suggesting that impairment of replication also contributes to resistance. To identify the viral gene product or products involved in VAM resistance, we isolated spontaneous resistance-breaking mutants by passing vein-banding (O strain) isolates several times through VAM plants. By comparing the amino acid sequences of the mutants with their original isolates, we identified a single amino acid substitution in the viral genome-associated protein (VPg) domain that is correlated with VAM resistance breaking. Together, these results suggest that, in addition to its role in replication, VPg plays an important role in the cell-to-cell movement of PVY.
摘要 据报道，烟草品种 Virgin A Mutant（VAM）具有隐性马铃薯 Y 病毒（PVY）抗性基因 va。接种不同日本 PVY 分离株的 VAM 植株表现出不同程度的抗性。VAM 对大多数测试的 PVY 分离株具有高度抗性，对 PVY-T 的三种坏死株系分离株具有耐性。基于组织印迹和压榨印迹获得的数据，这种抗性似乎主要在细胞间运动水平上。PVY 在 VAM 原质体中复制，但复制效率比敏感烟草低 30%，这表明复制受损也有助于抗性。为了鉴定与 VAM 抗性相关的病毒基因产物，我们通过多次将叶脉带（O 株）分离株通过 VAM 植株传递，分离出自发抗性突破突变体。通过比较突变体与原始分离株的氨基酸序列，我们在与病毒基因组相关的蛋白（VPg）结构域中鉴定出一个与 VAM 抗性突破相关的单一氨基酸取代。这些结果表明，VPg 除了在复制中起作用外，还在 PVY 的细胞间运动中起重要作用。
