Root rot, mainly caused by , is the most destructive disease affecting lily ( spp.) production. The WRKY transcription factors (TFs) have important roles during plant immune responses. To clarify the effects of WRKY TFs on plant defense responses to pathogens, a WRKY gene () was isolated from Wilson, which is a wild lily species highly resistant to . The expression of , which encodes a nuclear protein, is induced by various hormones (methyl jasmonate, ethephon, salicylic acid, and hydrogen peroxide) and by infection. In this study, -overexpressing transgenic tobacco plants were more resistant to than the wild-type plants. Moreover, the expression levels of jasmonic acid biosynthetic pathway-related genes (, and ), pathogenesis-related genes (, and ), and antioxidant stress-related superoxide dismutase genes (, and ) were significantly up-regulated in transgenic tobacco lines. Additionally, the transient expression of a hairpin RNA targeting increased the susceptibility of scales to . Furthermore, an resistance gene () encoding a chitinase was isolated from . An electrophoretic mobility shift assay demonstrated that LrWRKY2 can bind to the promoter containing the W-box element. Yeast one-hybrid assay results suggested that LrWRKY2 can activate transcription. An examination of transgenic tobacco transformed with and the promoter revealed that LrWRKY2 activates the promoter. Therefore, in , LrWRKY2 is an important positive regulator that contributes to plant defense responses to by modulating expression.