When Arabidopsis thaliana ecotype Col-0 was inoculated with a series of reassortant viruses created by exchanging viral genomic RNAs between two strains of cucumber mosaic virus (CMV), CMV(Y), and CMV(H), cell death developed in the leaves inoculated with reassortant CMV carrying CMV(H) RNA1 encoding 1a protein, but not in noninoculated upper leaves. In general, cell death in virus-infected plants is a critical event for virus survival because virus multiplication is completely dependent on host cell metabolism. However, interestingly, this observed cell death did not affect either virus multiplication in the inoculated leaves or systemic spread to noninoculated upper leaves. Furthermore, the global gene expression pattern of the reassortant CMV-inoculated leaves undergoing cell death was clearly different from that in hypersensitive response (HR) cell death, which is coupled with resistance to CMV. These results indicated that the observed cell death does not appear to be HR cell death but rather necrotic cell death unrelated to CMV resistance. Interestingly, induction of this necrotic cell death depended on single amino acid substitutions in the N-terminal region surrounding the methyltransferase domain of the 1a protein. Thus, development of necrotic cell death might not be induced by non-specific damage as a result of virus multiplication, but by a virus protein-associated mechanism. The finding of CMV 1a protein-mediated induction of necrotic cell death in A. thaliana, which is not associated with virus resistance and HR cell death, has the potential to provide a new pathosystem to study the role of cell death in virus-host plant interactions.

中文翻译：

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黄瓜花叶病毒1a蛋白中的单个氨基酸取代可导致病毒感染的叶片中坏死性细胞死亡，而不会影响病毒的繁殖。

当用两种黄瓜花叶病毒（CMV），CMV（Y）和CMV（H）菌株之间交换病毒基因组RNA产生的一系列重配病毒接种拟南芥Eco-0型Col-0时，接种的叶片中会出现细胞死亡携带带有编码1a蛋白的CMV（H）RNA1的重配CMV，但未在未接种的上部叶片中。通常，感染病毒的植物中的细胞死亡是病毒存活的关键事件，因为病毒的繁殖完全取决于宿主细胞的代谢。然而，有趣的是，这种观察到的细胞死亡并未影响病毒在接种叶片中的繁殖或系统扩散至未接种的上部叶片。此外，经历细胞死亡的重配CMV接种叶片的全球基因表达模式与超敏反应（HR）细胞死亡明显不同，后者与对CMV的抗性相关。这些结果表明观察到的细胞死亡似乎不是HR细胞死亡，而是与CMV抗性无关的坏死细胞死亡。有趣的是，这种坏死细胞死亡的诱导取决于1a蛋白甲基转移酶结构域周围N末端区域的单个氨基酸取代。因此，坏死细胞死亡的发展可能不是由病毒繁殖引起的非特异性损伤引起的，而是由病毒蛋白相关的机制引起的。发现CMV 1a蛋白介导的拟南芥坏死细胞死亡诱导