Jasmonic Acid Signals Involved in Valsa Canker Resistance Caused by C2H2-Type Transcription Factor PbeSTOP2 in Pyrus betulifolia

<i>Valsa</i> canker, a destructive necrotrophic disease caused by <i>Valsa</i> species (<i>V. mali</i> and <i>V. pyri</i>), threatens global apple and pear production. Resistance breeding has gained much attention because of its environmental friendliness and effectiveness, making it extremely critical to obtain key disease resistance genes. In this study, we identified that the expression of <i>PbeSTOP2</i><i>,</i> a C2H2-type transcription factor in 'Duli-G03' (<i>Pyrus betulifolia</i>, rootstock of pear), was induced in response to signals from <i>Vp</i> and <i>Vp</i> metabolites (<i>Vp</i>M). Transient expression in fruits and stable overexpression in suspension cells demonstrated that <i>PbeSTOP2</i> enhances resistance to <i>Vp</i>. In overexpressing cells, genes associated with jasmonic acid (JA) and pattern-triggered immunity (PTI) signaling were upregulated, and endogenous JA and auxin (IAA) levels increased. These results revealed that JA signaling was involved in the enhanced <i>Valsa</i> canker resistance conferred by <i>PbeSTOP2</i> overexpression. This finding on host disease resistance should facilitate the breeding efforts for <i>Valsa</i> canker resistance.