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Systemic Induction and Role of Mitochondrial Alternative Oxidase and Nitric Oxide in a Compatible Tomato--Tobacco mosaic virus Interaction

January 2010 , Volume 23 , Number  1
Pages  39 - 48

Li-Jun Fu,1 Kai Shi,1 Min Gu,1 Yan-Hong Zhou,1 De-Kun Dong,3 Wu-Sheng Liang,4 Feng-Ming Song,4 and Jing-Quan Yu1,2

1Department of Horticulture, Huajiachi Campus, Zhejiang University, 2Key Laboratory of Horticultural Plants Growth, Development and Quality Improvement, Agricultural Ministry of China, 3The Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, and 4Department of Plant Protection, Institute of Biotechnology, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou, P.R. China

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Accepted 19 June 2009.

The role of mitochondrial alternative oxidase (AOX) and the relationship between AOX and nitric oxide (NO) in virus-induced systemic defense to Tobacco mosaic virus (TMV) were investigated in susceptible tomato (Solanum lycopersicum) plants. TMV inoculation to the lower leaves induced a rapid NO synthesis and AOX activation in upper uninoculated leaves as early as 0.5 day postinoculation. Application of exogenous potassium cyanide (KCN, a cytochrome pathway inhibitor) at nonlethal concentrations and NO donor diethylamine NONOate (DEA/NO) to the upper uninoculated leaves greatly induced accumulation of AOX transcript, reduced TMV viral RNA accumulation, and increased the leaf photochemical quantum yield at photosystem II. Pretreatment with NO scavenger almost completely blocked TMV-induced AOX induction and substantially increased TMV susceptibility. Salicylhydroxamic acid (SHAM, an AOX inhibitor) pretreatment reduced the DEA/NO-induced cyanide-resistant respiration and partially compromised induced resistance to TMV. Conversely, KCN and SHAM pretreatment had very little effect on generation of NO, and pretreatment with NO scavenger did not affect KCN-induced AOX induction and TMV resistance. These results suggest that TMV-induced NO generation acts upstream and mediates AOX induction which, in turn, induces mitochondrial alternative electron transport and triggers systemic basal defense against the viral pathogen.

© 2010 The American Phytopathological Society