Oxathiapiprolin was developed as a specific plant pathogenic oomycete inhibitor, previously shown to have highly curative and protective activities against the pepper Phytophthora blight disease under field and greenhouse tests. Therefore, it was hypothesized that
oxathiapiprolin might potentially activate the plant disease resistance against pathogen
infections. This study investigated the potential and related mechanism of
oxathiapiprolin to activate the plant disease resistance using the bacterium Pseudomonas syringae pv tomato (Pst) and plant Arabidopsis interaction as the targeted system. Our results showed that
oxathiapiprolin could activate the plant disease resistance against Pst DC3000, a non-target pathogen of
oxathiapiprolin, in Arabidopsis, tobacco, and tomato plants. Our results also showed the enhanced
callose deposition and H2O2 accumulation in the
oxathiapiprolin-treated Arabidopsis under the induction of flg22 as the
pathogen-associated molecular pattern (
PAMP) treatment. Furthermore, increased levels of free
salicylic acid (SA) and
jasmonic acid (JA) were detected in the
oxathiapiprolin-treated Arabidopsis plants compared to the mock-treated ones under the challenge of Pst DC3000. Besides, the gene expression results confirmed that at 24 h after the infiltration with Pst DC3000, the
oxathiapiprolin-treated Arabidopsis plants had upregulated expression levels of the
respiratory burst oxidase homolog D (RBOHD), JA-responsive gene (PDF1.2), and SA-responsive genes (PR1, PR2, and PR5) compared to the control. Taken together,
oxathiapiprolin is identified as a novel chemical inducer which activates the plant disease resistance against Pst DC3000 by enhancing the
callose deposition, H2O2 accumulation, and
hormone SA and JA production.