Mechanism Research on Cinnamaldehyde Enhances Pepper Resistance to Phytophthora Blight Disease

In order to understand the mechanism that cinnamaldehyde(CA)can enhance pepper resistance to phytophthora blight disease,we investigated the antifungal effect of CA on Phytophthora capsici in vitro and the controlling effect on disease development as well as the regulation of defensive response in pepper seedlings by CA.Basically,we obtained the following results:(1)the EC50 for CA against isolate NJ01 used in this study was 0.81 mmol/L;CA treatment resulted in the abnormally broken mycelia of NJ01 and cell death indicated by PI staining.(2)Pepper seedlings inoculated with NJ01 alone showed obvious disease symptoms,such as black brown atrophic sub-stem,plant lodging,leaf abscission,and decreased biomass.However,pepper seedlings inoculated with CA-treated NJ01 with increased fresh weight and chlorophyll content grew well without any obvious disease symptoms.(3)Compared to the NJ01 inoculation alone,inoculation with CA-treated NJ01 resulted in the significant increases in the activities of anti-oxidative enzymes(e.g.CAT,POD,and SOD)and the contents of antioxidants(e.g.GSH and ASA).In conclusion,it can be speculated that pepper enhanced resistance to pepper phytophthora blight disease by CA may attribute to the antifungal effect of CA and CA-modulated plant defense in pepper seedlings.