肉桂醛对增强辣椒疫霉病抗性的作用机制研究

该实验以辣椒疫霉菌(Phytophthora capsici)致病性菌株NJ01和‘苏椒5号’辣椒幼苗为研究对象,通过肉桂醛对辣椒疫霉菌的体外抑菌作用、室内侵染效果以及对辣椒幼苗防卫反应的调控作用,揭示肉桂醛对增强辣椒疫霉病抗性的作用机制。结果表明:(1)肉桂醛对实验所用致病性菌株NJ01的抑制中浓度(EC50)值为0.81mmol/L;肉桂醛处理可导致NJ01菌丝严重皱缩、畸形、断裂;PI染色显示NJ01菌丝出现明显的细胞死亡现象。(2)单独NJ01菌株接种的辣椒植株表现出明显病症(茎基部变黑褐色、干枯萎缩,植株倒伏,叶片脱落,生物量下降);而肉桂醛处理2h后接种NJ01菌株的辣椒植株长势良好,无明显病症,鲜重和叶绿素含量显著上升至对照水平。(3)与单独接种NJ01菌株处理相比,肉桂醛处理2h后接种NJ01菌株的辣椒植株体内抗氧化酶(CAT、SOD、POD)活性显著上升,抗氧化物质(GSH和ASA)含量显著增加。研究认为,肉桂醛可能通过抑制辣椒疫霉菌的生长及其对辣椒植株的侵染能力,同时调控辣椒植株防卫反应,进而提高辣椒对疫病抗性。

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.