Acts Positively in Pepper ( L.) Immunity against .

Bacterial wilt caused by is one of the most important diseases in solanaceous plants, including peppers. It generally tends to be more serious under warm-temperature and moist (WM) conditions than at moist room-temperature (RM) conditions. Although immunity mechanisms at room temperature have been intensively studied, the mechanisms underlying WM conditions remain poorly understood. Herein, the pepper cysteine protease CaZingipain2 was expressed and functionally characterized in pepper immunity against at WM conditions and at room temperature. The results showed that CaZingipain2 localized to the nucleus and was upregulated at the transcript level in pepper plants upon infection under WM conditions (RSWM). Virus-induced gene silencing of significantly increased the susceptibility of pepper plants to RSWM, and was coupled with the downregulation of and , which are specifically related to pepper immunity against RSWM, according to our previous studies, while its overexpression significantly reduced the susceptibility of plants to RSWM compared to that of wild-type plants. In addition, our data showed that CaZingipain2 also acts positively in pepper immunity against infection at room temperature by upregulating the SA- and JA-responsive PR genes, including and . All these results indicate that improves pepper immunity against under WM conditions and at room temperature by regulating different PR genes.