病原菌对Strobilurin类杀菌剂抗药性机理的研究进展

结合strobilurin类杀菌剂作用机制的特点,通过室内和田间研究的结果总结了病原菌对该类杀菌剂产生抗药性的主导机制。Strobilurin类杀菌剂主要结合于病原菌细胞色素bc1复合物中细胞色素b部分的Qo位点,而细胞色素b由突变率很高的线粒体基因组编码,所以病原菌很容易因该基因的突变而导致抗药性发生。至今已至少有14种寄主植物上的25种病原菌在田间表现出了对strobilurin类杀菌剂的抗药性。抗药性产生的主要机理是病原菌细胞色素b的氨基酸残基发生了单点取代。田间抗性菌株的主要取代位点是G143A、F129L和G143R。一些非靶标生物细胞色素b的143位为丙氨酸,这可能是strobilurin类杀菌剂对其表现安全性的原因之一。由于锈病病菌Puccinia spp.中内含子剪切位点恰好出现在编码G143的GGT之后,G143A的突变会导致突变菌株的死亡,因而它们在田间不会表现出抗药性。此外,Qo抑制剂阻断电子传递后会导致胞内活性氧(ROS)的增加,而ROS可以诱导细胞交替氧化酶(AOX)的表达,进而启动线粒体的旁路氧化途径,使病原菌表现出抗药性。因此,病原菌氨基酸残基的单点取代和交替氧化途径是导致病原菌对strobilurin杀菌剂产生抗药性的主导机制。

Progress on Study of Resistance Mechanism of Strobilurin Fungicides

The main resistance mechanism of strobilurin fungicides was reviewed according to the documents of laboratory studies and field experiments and their characteristics of mode of action.Strobilurin fungicides mainly bind to Qo site of cytochrome b of the cytochrome bc₁ complex in fungi .Since cytochrome b is coded by mitochondrial DNA with high mutant frequency,fungi are easily to express resistance to Qo inhibitors as a result of the DNA mutation.After 10 years of field application,at least 25 pathogens on 14 hosts have already developed resistance to strobilurin fungicides.The resistance mechanism of strobilurin fungicides is mainly amino acid residue single point substitution of the cytochrome b in fungi,and the substitution in the field resistance was G143A,F129L or G137R,respectively.However,in some non-target organism the amino acid residue 143 of the cytochrome b is alanine,and this is the reason of why they show resistance to strobilurin fungicides in all probability.Since the intron scissor position of rust pathogens (Puccinia spp.) tagged behind GGT encoding G143 in cytochrome b,and the substitution of G143A would cause the death of the pathogen,therefore,rust seldom develops resistance to strobilurin fungicides that caused by substitution of G143A in the field.Furthermore,if Qo inhibitors inhibit the electron transport in mitochondrial,the reactive oxygen species (ROS) will burst,which will induce cells to express alternative oxidase (AOX) and subsequently startup alternative pathway to cause resistance towards strobilurin fungicides.Therefore,amino acid residue single point substitution and expression of AOX are the main mechanisms of fungi resistance to strobilurins.