马铃薯晚疫病菌对甲霜灵抗性机制的初步研究

 选取对甲霜灵敏感、中抗和高抗的马铃薯晚疫病菌(Phytophthora infestans)菌株各2株,采用电导率法和同位素掺入法,研究了甲霜灵对马铃薯晚疫病菌不同抗药性水平菌株细胞膜通透性和RNA聚合酶活性的影响,借助液相色谱分析方法检测了不同抗药性水平菌株对甲霜灵的降解作用。结果表明:甲霜灵对马铃薯晚疫病菌不同抗药性水平菌株的细胞膜通透性没有明显影响;随着甲霜灵浓度提高,敏感菌株的RNA聚合酶活性受到显著抑制,10μg/mL甲霜灵对敏感菌株RNA聚合酶活性的抑制率达到40%以上,而10和100μg/mL甲霜灵对高抗菌株的RNA聚合酶活性只表现轻微的抑制作用,抑制作用分别小于8%和21%,甲霜灵对中抗菌株RNA聚合酶活性的抑制作用介于对敏感菌株和高抗菌株的抑制作用之间。抗性菌株对甲霜灵有一定的降解作用,培养30d后高抗菌株HL105和SC1的降解率分别达到13.46%和16.14%。

Preliminary study on the mechanism of resistance to metalaxyl in Phytophthora infestans

Isolates of Phytophthora infestans, two sensitive, two intermediate, and two highly resistant ones to metalaxyl,were selected. The membrane permeability and endogenous RNA polymerase activities were examined by means of the con-ductivity and radioactive isotopic incorporation technique, metalaxyl decomposition was also tested by HPLC. The resultsshowed that metalaxyl displayed no significant effects on the membrane permeability of the three kinds of isolates with dif-ferent sensitivities to metalaxyl. RNA polymerase activities of the sensitive isolates were strongly inhibited as metalaxyl con-centration increased. The inhibition rate was more than 40% when the concentration of metalaxyl was kept at 10 μg/mL.Metalaxyl slightly inhibited RNA polymerase activities of the highly resistant isolates, the inhibition percentage was lowerthan 8% and 21%, respectively, when the concentrations of metalaxyl were at 10 μ/mL and 100 μ/mL. The inhibitionof RNA polymerase activities of intermediate isolates was between the sensitive isolates and highly resistant isolates. The re-sistant isolates HL105 and SC1 presented some effects on decomposition of metalaxyl, and the decomposition rate was13.46% and 16.14%, 30 days after incubation of the isolates.