The bacterial wilt, caused by Ralstonia solanacearum, is an important disease for eggplants, which control is difficult. Induction of resistance in plants is a promising method for disease control. Fruiting bodies of Agaricus blazei and Lentinula edodes have substances that exhibit antibiotic activity or are able of acting as elicitors of resistance in plants. The objectives of the present work were to verify the effect of aqueous extracts from the mushrooms and the plant activator acibenzolar-S-methyl (aSm) on in vitro bacterial growth and to control bacterial wilt as well as to investigate the activity of certain enzymes. The inhibitory effect on the pathogen was evaluated by using different concentrations of aqueous extracts. The induced resistance was studied in plants treated with the biological or chemical inducers, by measuring the intensity of wilt and alterations in some defense-related enzymes. The results showed that the isolates of A. blazei and L. edodes, used in several dilutions, did not inhibit in vitro bacterial growth. The extracts of the isolates Abl-11 and Abl-28 from A. blazei (15%, v/v) and aSm (0,05 g/L) caused significant reduction in the occurrence of wilted leaves, when applied two days before inoculation. Plants treated with aSm or aqueous extracts of Abl-11 and Abl-28 exhibited increased peroxidase activity. The chitinase, phenylalanine ammonia-lyase and polyphenoloxidase activities did not change in plants treated with Abl-28 and aSm. However, plants treated with Abl-11 exhibited increased phenylalanine ammonia-lyase and polyphenoloxidase activities, while the chitinase activity was not affected. Based upon the results, it was shown that the aSm and the isolates Abl-11 and Abl-28 of A. blazei exhibited a potential to induce resistance in eggplants against R. solanacearum.
bacterial wilt; PR-protein; biotic inducers
