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Salicylic Acid-Induced Resistance to Cucumber mosaic virus in Squash and Arabidopsis thaliana: Contrasting Mechanisms of Induction and Antiviral Action

May 2005 , Volume 18 , Number  5
Pages  428 - 434

Carl N. Mayers , 1 Kian-Chung Lee , 2 Catherine A. Moore , 1 Sek-Man Wong , 2 and John P. Carr 1

1Plant Sciences Department, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K.; 2Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Singapore

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Accepted 9 December 2004.

Salicylic acid (SA)-induced resistance to Cucumber mosaic virus (CMV) in tobacco (Nicotiana tabacum) results from inhibition of systemic virus movement and is induced via a signal transduction pathway that also can be triggered by antimycin A, an inducer of the mitochondrial enzyme alternative oxidase (AOX). In Arabidopsis thaliana, inhibition of CMV systemic movement also is induced by SA and antimycin A. These results indicate that the mechanisms underlying induced resistance to CMV in tobacco and A. thaliana are very similar. In contrast to the situation in tobacco and A. thaliana, in squash (Cucurbita pepo), SA-induced resistance to CMV results from inhibited virus accumulation in directly inoculated tissue, most likely through inhibition of cell-to-cell movement. Furthermore, neither of the AOX inducers antimycin A or KCN induced resistance to CMV in squash. Additionally, AOX inhibitors that compromise SAinduced resistance to CMV in tobacco did not inhibit SAinduced resistance to the virus in squash. The results show that different host species may use significantly different approaches to resist infection by the same virus. These findings also imply that caution is required when attempting to apply findings on plant-virus interactions from model systems to a wider range of host species.

Additional keywords: phloem , plasmodesmata , systemic acquired resistance .

© 2005 The American Phytopathological Society