Lipoxygenase and glutathione peroxidase activity in tobacco leaves inoculated with tobacco mosaic virus

Künstler, A. and Király, L. and Pogány, M. and Tóbiás, I. and Gullner, G. (2007) Lipoxygenase and glutathione peroxidase activity in tobacco leaves inoculated with tobacco mosaic virus. Acta Phytopathologica et Entomologica Hungarica, 42 (2). pp. 197-207. ISSN 0238-1249

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Abstract

Fatty acid hydroperoxide-producing lipoxygenase (LOX) and hydroperoxide-degrading glutathione peroxidase (GPOX) enzyme activities were studied in leaves of virus resistant Xanthi-nc and susceptible Samsun-nn tobacco cultivars after inoculation with Tobacco mosaic virus (TMV). Total LOX activity showed a maximum at pH 5.5 in cell-free extracts of uninfected leaves. LOX activity markedly increased at this pH after TMV inoculation, but a substantial induction was detected also in the basic pH range with an emerging peak around pH = 8.5. TMV-elicited LOX induction was weaker and appeared later in Samsun-nn than in Xanthi-nc leaves. GPOX activity was also substantially induced by TMV infection. However, this induction appeared only 4 days post-inoculation in resistant Xanthi-nc plants in tissues surrounding the localized necrotic lesions. In contrast, GPOX activity did not change in TMV-inoculated, susceptible Samsun-nn leaves. Several glutathione S-transferase (GST) isoenzymes also display GPOX activity. The expression of a tau class GST gene was markedly induced by TMV inoculation in Xanthi-nc leaves. This tobacco GST gene was partially cloned and sequenced.

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