Antioxydant response to biotic and abiotic inducers for the resistance against Fusarium wilt disease in eggplant (Solanum melongena L.)

Abstract

Acibenzolar-S-methyl as an abiotic plant activator and a non-host isolate of Fusarium oxysporum on eggplant (F. oxysporum f. sp. melonis) as a biotic inducer were applied to eggplant seedlings in order to confer increased resistance to F. oxysporum f. sp. melongenae, the causal agent of Fusarium wilt of eggplant. Acibenzolar-S-methyl and F. oxysporum f. sp. melonis were applied 72 h before pathogen inoculation and the development of disease symptoms was assessed with a Fusarium yellow rating at 7th, 11th, 14th, 17th and 21th day after inoculation. Pretreatment of eggplants with Acibenzolar-S-methyl and F. oxysporum f. sp. melonis significantly reduced the severity of Fusarium wilt disease. The severity of the disease in positive control plants reached to 92.50% whereas that of acibenzolar-S-methyl and F. oxysporum f. sp. melonis-pretreated seedlings of eggplants was only 32.21% and 21.13%, respectively, 21 days after inoculation. Acibenzolar-S-methyl and F. oxysporum f. sp. melonis pretreatments resulted in a hypersensitive reaction and triggered the elaboration of histological barriers such as callose and H2O2 synthesis. In situ studies demonstrated that the hydrogen peroxide (H2O2) accumulation and the callose deposition as responses to the pathogen attack started 24 h after inoculation. Acibenzolar- S-methyl and F. oxysporum f. sp. melonis-pretreated plants also showed significant increases in the activity of catalase and polyphenol oxidase enzymes along with the increase of proline and H2O2 content when compared to F. oxysporum f. sp. melongenae-infected plants.