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Chemically Induced Virus Resistance in Arabidopsis thaliana Is Independent of Pathogenesis-Related Protein Expression and the NPR1 Gene

January 2002 , Volume 15 , Number  1
Pages  75 - 81

Chui Eng Wong , Rachael A. J. Carson , and John P. Carr

Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA U.K.

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Accepted 1 October 2001.

Salicylic acid (SA) treatment triggers inhibition of replication or movement of several positive-sense RNA plant viruses in tobacco. This resistance can also be stimulated by nonlethal concentrations of cyanide and antimycin A (AA) without triggering induction of pathogenesis-related PR-1 protein genes. In two ecotypes of Arabidopsis thaliana (Columbia and Nössen), SA-induced resistance to a tobamovirus, Turnip vein clearing virus (TVCV), was also induced by nonlethal concentrations of cyanide and AA without concomitant induction of PR-1 gene expression. Furthermore, chemically induced resistance to TVCV, as well as the induction of the plant mitochondrial alternative oxidase (a potential target for the chemicals), was independent of NPR1, a gene that plays a key role downstream of SA in the induction of PR proteins. The chemically induced resistance to TVCV appeared to be due to inhibition of replication at the site of inoculation. Taken together, these results show that in Arabidopsis, as in tobacco, resistance to viruses can be induced via a distinct branch of the defensive signal transduction pathway. This suggests that the existence of this virus-specific branch may be widespread among plants.

© 2002 The American Phytopathological Society