Adathoda vasica leaf extract induces resistance in rice against bacterial leaf blight disease (Xanthomonas oryzae pv. oryzae).

Abstract

Three plants extracts were used for the management of Xanthomonas oryzae pv. oryzae in vitro. The efficacy of the plant extracts was tested by antibacterial activity and was used as seed treatment to know the enhancement of seed germination and seedling vigour. Beside promising results given, plant extracts were tried under greenhouse studies to test the efficacy in controlling bacterial blight disease incidence. To get the molecular level of evidence and the estimated defense enzymes in plant extracts, plants were treated, after challenge inoculation, with a target pathogen at different intervals. Adathoda vasica leaf extract significantly reduced the bacterial leaf blight pathogen, X. oryzae pv. oryzae (Xoo) in vitro. Seed treatment was found to be effective in reducing the incidence of the disease under greenhouse condition. Physiological observation of A. vasica treated plants indicated that restriction of pathogen colonization or disease development in plant tissue was correlated with the pronounced increase of peroxidase, PAL, b-1, 3-glucanase, polyphenol oxidase and phenol activity after challenge inoculation with the target pathogen. This investigation clearly demonstrated that the A. vasica leaf extract has the ability to induce the activation of defense enzymes accumulation which can be associated with induction of resistance against rice bacterial leaf blight. Key words: Adathoda vasica, bacterial leaf blight, defense enzymes, induced systemic resistance, rice, Xanthomonas oryzae pv. oryzae.