The WRKY transcription factor PlWRKY65 enhances the resistance of Paeonia lactiflora (herbaceous peony) to Alternaria tenuissima

Abstract

In this study, the disease resistance gene <i>PlWRKY65</i> was isolated from the leaves of <i>Paeonia lactiflora</i> and analyzed by bioinformatics methods, and the localization of the encoded protein was explored. Quantitative real-time PCR (qRT-PCR) was also used to explore the response of this gene to <i>Alternaria tenuissima</i>. The results showed that the gene sequence contained multiple cis-acting elements involved in the response to hormone signaling molecules belonging to the IIe subgroup of the WRKY family, and the encoded proteins were located in the nucleus. The <i>PlWRKY65</i> gene has a positive regulatory effect on <i>A. tenuissima</i> infection. After silencing the <i>PlWRKY65</i> gene via virus-induced gene silencing (VIGS), it was found that the gene-silenced plants were more sensitive to <i>A. tenuissima</i> infection than the wild plants, exhibiting more severe infection symptoms and different degrees of changes in the expression of the pathogenesis-related (PR) genes. In addition, we showed that the endogenous jasmonic acid (JA) content of <i>P. lactiflora</i> was increased in response to <i>A. tenuissima</i> infection, whereas the salicylic acid (SA) content decreased. After <i>PlWRKY65</i> gene silencing, the levels of the two hormones changed accordingly, indicating that <i>PlWRKY65</i>, acting as a disease resistance-related transcriptional activator, exerts a regulatory effect on JA and SA signals. This study lays the foundation for functional research on WRKY genes in <i>P. lactiflora</i> and for the discovery of candidate disease resistance genes.