A Necrosis-Inducing Elicitor Domain Encoded by Both Symptomatic and Asymptomatic Plantago asiatica mosaic virus Isolates, Whose Expression Is Modulated by Virus Replication

作者：Komatsu Ken; Hashimoto Masayoshi; Maejima Kensaku; Shiraishi Takuya; Neriya Yutaro; Miura Chihiro; Minato Nami; Okano Yukari; Sugawara Kyoko; Yamaji Yasuyuki; Namba Shigetou^*

来源：Molecular Plant-Microbe Interactions, 2011, 24(4): 408-420.

DOI：10.1094/MPMI-12-10-0279

Systemic necrosis is the most destructive symptom induced by plant pathogens. We previously identified amino acid 1154, in the polymerase domain (POL) of RNA-dependent RNA polymerase (RdRp) of Plantago asiatica mosaic virus (PlAMV), which affects PlAMV-induced systemic necrosis in Nicotiana benthamiana. By point-mutation analysis, we show that amino acid 1,154 alone is not sufficient for induction of necrotic symptoms. However, PlAMV replicons that can express only RdRp, derived from a necrosis-inducing PlAMV isolate, retain their ability to induce necrosis, and transient expression of PlAMV-encoded proteins indicated that the necrosis-eliciting activity resides in RdRp. Moreover, inducible-overexpression analysis demonstrated that the necrosis was induced in an RdRp dose-dependent manner. In addition, during PlAMV infection, necrotic symptoms are associated with high levels of RdRp accumulation. Surprisingly, necrosis-eliciting activity resides in the helicase domain (HEL), not in the amino acid 1,154-containing POL, of RdRp, and this activity was observed even in HELs of PlAMV isolates of which infection does not cause necrosis. Moreover, HEL-induced necrosis had characteristics similar to those induced by PlAMV infection. Overall, our data suggest that necrotic symptoms induced by PlAMV infection depend on the accumulation of a non isolate specific elicitor HEL (even from nonnecrosis isolates), whose expression is indirectly regulated by amino acid 1,154 that controls replication.

• 出版日期2011-4