Overexpression of a New Chitinase Gene EuCHIT2 Enhances Resistance to Erysiphe cichoracearum DC in Tobacco Plants.

In this study, we cloned a new chitinase gene, , from Oliver () using rapid amplification of cDNA ends (RACE) technology and constructed an overexpression vector, pSH-35S-2, to introduce it into tobacco ( cv. Xanthi) Resistance to de Candolle (E.cichoracearum DC) and molecular mechanisms in the transgenic tobacco were determined by drop inoculation, spore counting, determination of physicochemical indicators, and analysis of gene expression. The chitinase activity and resistance to DC were significantly higher in the transgenic tobacco than in wild-type tobacco (p < 0.05). The activities of peroxidase (POD) and catalase (CAT), after inoculation with DC, were higher in the transgenic tobacco than in the wild-type. Conversely, the malondialdehyde (MDA) content was significantly lower in the transgenic tobacco than the wild-type before and after inoculation. In addition, our study also indicated that the resistance to DC might involve the salicylic acid (SA) and jasmonic acid (JA) pathways, because the expression levels of pathogenesis-related gene 1 () and () were significantly increased and decreased, respectively, after inoculation with DC. The present study supports the notion that and POD participate in resistance to DC in the transgenic tobacco plants.