新型杀菌剂氟醚菌酰胺对辣椒疫霉的作用机制初探

Preliminary studies on the action mechanism of the novel fungicide LH-2010A against Phytophthora capsici

为研究氟醚菌酰胺(N-(3-氯-5-(三氟甲基)吡啶-2-甲基)-2,3,5,6-四氟-4-甲氧基苯甲酰胺)对辣椒疫霉的作用机制,采用生物测定法系统测定了氟醚菌酰胺对辣椒疫霉菌丝生长、游动孢子释放和菌丝生长量的影响,并进一步对药剂处理后的辣椒疫霉菌丝的超微结构进行了观察;同时测定了氟醚菌酰胺对病原菌糖酵解、三羧酸循环和磷酸戊糖3种呼吸代谢途径的影响,以及其对辣椒疫霉菌丝体细胞膜通透性、可溶性蛋白和DNA含量的影响。结果表明:氟醚菌酰胺对辣椒疫霉菌丝生长、游动孢子释放和菌丝生长量的EC50值分别为7.14、16.34和5.12μg/m L;其可使辣椒疫霉菌丝分支增多变短,且出现细胞壁增厚和细胞变形现象;ATP的存在能降低氟醚菌酰胺对辣椒疫霉菌丝的抑制作用,说明氟醚菌酰胺对辣椒疫霉能量产生过程有一定的抑制作用;其对三羧酸循环途径的抑制作用最为明显。电导率法测定结果表明,氟醚菌酰胺处理均能提高辣椒疫霉的细胞膜通透性,用100μg/m L的氟醚菌酰胺处理400 min后,菌株的相对渗率达78.23%。但氟醚菌酰胺对辣椒疫霉生物大分子的影响较小。研究结果初步表明,氟醚菌酰胺有多个作用位点,但主要是通过抑制辣椒疫霉能量产生和细胞膜通透性而起到抑菌作用。

The action mechanism of N-（3-chloro-5-（trifluoromethyl） pyridine-2-methyl-2, 3, 5, 6-four fluorine-4-methoxy benzamide（LH-2010A） against Phytophthora capsici was investigated. Bioassay method was adopted to determine the toxicity of LH-2010 A against mycelial growth, zoospores release and mycelial yield of P. capsici. Morphology and ultrastructure of mycelial treated with LH-2010 A were studied. Mycelial respiration rate test was also conducted to evaluate the inhibition effect to metabolic approaches, including embden-meyerhof-parnas（EMP）, tricarboxylic acid cycle（TCA） and hexose monophophate（HMP）. The effect of LH-2010 A on the permeability of the cell membrane,protein biosynthesis and DNA biosynthesis were determined. The results demonstrated that inhibition effect to P. capsici by LH-2010 A was observed at different stages in the life cycle of P. capsici,including the mycelial growth, the zoospores release and the mycelial yield, with EC50 values of 7.14,16.34 and 5.12 μg/m L, respectively. Morphological and ultrastructural studies showed that LH-2010 A caused the excessive branching and swelling of hyphae as well as the development of a thicker and multilayer cell wall. The inhibition of LH-2010 A on mycelial growth was reduced by the addition of ATP, which suggested that the action mechanism of LH-2010 A was connected with impairment of the energy generation system. Specifically, the approach of TCA was inhibited by LH-2010 A significantly.The conductivity of mycelia cell suspension increased in the presence of LH-2010 A, which indicated that LH-2010 A affected the cell membrane permeability. The relative leakage of mycelia cell suspension treated with 100 μg/m L LH-2010 A for 400 minutes was 78.23%. However, LH-2010 A had little effect on the biosynthesis of protein and DNA. These results suggested that LH-2010 A exhibited multiple modes of actions including the impairment of the energy generation system and the influence on the cell membrane permeability directly or indirectly.