Establishment of Acquired Resistance Confers Reduced Levels of Superoxide and Hydrogen Peroxide in TMV-infected Tobacco Leaves

Author： Y. M Hafez J. Fodor Z. Király

Publisher： Akademiai Kiado

ISSN： 0238-1249

Source： Acta Phytopathologica et Entomologica Hungarica, Vol.39, Iss.4, 2004-11, pp. : 347-359

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Abstract

Infection of some leaves of Xanthi-nc tobacco with tobacco mosaic virus (TMV) induces systemic acquired resistance (SAR) in remote leaves of the plant to a second (challenge) infection, and therefore produces only a limited necrotization in the resistant leaves. Here we show that the levels of superoxide and hydrogen peroxide are lower in the remote infected leaves exhibiting the SAR. Treatment of leaves of Xanthi-nc tobacco with benzothiadiazole (BTH) also suppresses tissue necrotization and accumulation of superoxide and hydrogen peroxide upon TMV inoculation. However, both of these reactive oxygen species are up-regulated and tissue necrotization is increased in a transgenic NahG tobacco, which is unable to produce a SAR response. Treatment of TMV-infected NahG leaves with BTH also resulted in a reduced level of necrotization and an attenuated accumulation of superoxide and hydrogen peroxide after inoculation with TMV. Thus, the level of reactive oxygen species seems to be correlated with the size and number of necrotic lesions caused by TMV. It would seem that reactive oxygen species play a pivotal role in TMV-induced cell death response.