Molecular Plant-Microbe Interactions (2011) 24, 408-420

Ken Komatsu, Masayoshi Hashimoto, Kensaku Maejima, Takuya Shiraishi, Yutaro Neriya, Chihiro Miura, Nami Minato, Yukari Okano, Kyoko Sugawara, Yasuyuki Yamaji and Shigetou Namba (2011)
A necrosis-inducing elicitor domain encoded by both symptomatic and asymptomatic Plantago asiatica mosaic virus isolates, whose expression is modulated by virus replication
Molecular Plant-Microbe Interactions 24 (4), 408-420
Abstract: 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.
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Database assignments for author(s): Shigetou Namba

Research topic(s) for pests/diseases/weeds:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plantago asiatica mosaic virus