Response of oxidative metabolism to the application of carbendazim plus boron in tobacco

Abstract

In view of the essential role of oxidative process in the development of pathogen resistance in plants, the aim of the present study was to determine the individual effect of a fungicide, as well as to determine the combined effect of the fungicide and boron (B) on superoxide dismutase (SOD), guaiacol peroxidase (GPX), catalase (CAT), and ascorbate peroxidase (APX) activities and H ₂ O ₂ levels in tobacco plants (Nicotiana tabacum L. cv. Tennessee 86). The fungicide applied was carbendazim (carb) at a concentration of 2.6 mM . Boron was applied as H ₃ BO ₃ at: 1.6 mM (B₁), 4 mM (B₂), 8 mM (B₃), 16 mM (B₄), 32 mM (B₅), and 64 mM (B₆). The results indicated that foliar application of carbendazim by itself does not increase SOD, GPX, CAT or APX activities or H₂ O₂ foliar accumulation. The combined application of carbendazim and B increased SOD, GPX, CAT, and APX activities, especially in carb-B₃ and carb-B₄ . This effect may signify an additional tolerance mechanism to pathogenic infection, given the participation of these enzymes in the early phases of the plant–pathogen interactions.