Melatonin Mitigates the Infection of via Modulation of the Chitinase Gene and Antioxidant Activity in L.

Anthracnose, caused by , is one of the most damaging pepper ( L.) disease. Melatonin induces transcription of defense-related genes that enhance resistance to pathogens and mediate physiological activities in plants. To study whether the melatonin-mediated pathogen resistance is associated with chitinase gene (), pepper plants and Arabidopsis seeds were treated with melatonin, then activation, hydrogen peroxide (HO) levels, and antioxidant enzymes activity during plant-pathogen interactions were investigated. Melatonin pretreatment uncoupled the knockdown of and transiently activated its expression level in both control and -silenced pepper plants and enhanced plant resistance. Suppression of in pepper plants showed a significant decreased in the induction of defense-related genes and resistance to pathogens compared with control plants. Moreover, melatonin efficiently enabled plants to maintain intracellular HO concentrations at steady-state levels and enhanced the activities of antioxidant enzymes, which possibly improved disease resistance. The activation of the chitinase gene in transgenic Arabidopsis lines was elevated under infection and exhibited resistance through decreasing HO biosynthesis and maintaining HO at a steady-state level. Whereas melatonin primed -overexpressed (OE) and wild-type (WT) Arabidopsis seedlings displayed a remarkable increase in root-length compared to the unprimed WT plants. Using an array of knockdown and OE, we found that melatonin efficiently induced and other pathogenesis-related genes expressions, responsible for the innate immunity response of pepper against anthracnose disease.