樱桃采后灰霉病菌对甲基硫菌灵、乙霉威和腐霉利的抗性

Resistance of Botrytis cinerea to thiophanate-methyl,diethofencarb,and procymidone in postharvest cherry

本文采用单孢分离法对四川汉源和山东烟台等地采集的樱桃果实进行了采后灰霉病的病原菌分离和鉴定;采用区分剂量法分别测定了菌株对苯并咪唑类杀菌剂甲基硫菌灵、乙霉威和二甲酰亚胺类杀菌剂腐霉利的敏感性,并进一步分析了抗药性菌株的分子机制。结果表明,分离得到的54株樱桃采后灰霉病菌均为灰葡萄孢Botrytis cinerea,对甲基硫菌灵的总抗性频率高达79.6%,其中甲基硫菌灵抗性-乙霉威敏感(BEN R1)菌株频率为25.9%;甲基硫菌灵-乙霉威双重抗性菌株(BEN R2)频率为53.7%;检测到腐霉利抗性菌株(DCF R)9株,频率为16.7%。甲基硫菌灵抗性菌株在β-tubulin基因上的突变共有2种类型:BEN R1抗性菌株中,第198位密码子发生点突变(GAG→GCG),编码氨基酸由Glu(E)突变成缬氨酸Ala(A);在BEN R2抗性菌株中,第198位密码子发生点突变(GAG→GTG),编码氨基酸由Glu(E)突变成缬氨酸Val(V)。DCF R菌株在BcOS1的第365位密码子由ATC突变成AAC或AGC,导致编码的氨基酸由异亮氨酸Ile(I)突变成天冬酰胺Asn(N)或丝氨酸Ser(S)。本研究表明樱桃采后灰霉病菌对甲基硫菌灵和腐霉利存在不同程度抗性,应在加强抗药性监测的同时与其他类型杀菌剂交替使用,延缓抗药性发展。

The pathogenic fungi of postharvest grey mold on cherry fruits from Hanyuan,Sichuan Province,and Yantai,Shandong Province were collected and identified by single-spored method.The sensitivity of the tested strains to thiophanate-methyl,diethofencarb,and procymidone was determined by differential dose method.The alignments of the DNA sequences ofβ-tubulin gene and BcOS1 gene were carried out to analyze the molecular mechanism of resistant strains.The results showed that the 54 isolates collected from postharvest cherry were Botrytis cinerea,and the total resistance frequency to thiophanate-methyl was 79.6%.Among them,the resistance frequency of thiophanate-methyl-resistant and diethofencarb-sensitive strains(BEN R1)was 25.9%.The resistance frequency of strains resistant to both thiophanate-methyl and diethofencarb(BEN R2)was 53.7%.Nine procymidone-resistant strains(DCF R)were detected,and the resistance frequency was 16.7%.There were two types of mutation inβ-tubulin gene of benzimidazole-resistant strains.In BEN R1,the codon at position 198 was mutated from GAG to GCG,resulting in the amino acid encoded by Glutamate-Glu(E)being changed to Alanine-Ala(A).In BEN R2,the codon at position 198 was mutated from GAG to GTG,resulting in the change of the encoded amino acid from Glu(E)to valine-Val(V).The codon at position 365 in BcOS1 gene of DCF R was mutated from ATC to AAC or AGC,resulting in the change of the encoded amino acid from isoleucine-Ile(I)to asparagine-Asn(N)or serine-Ser(S).The results indicated that B.cinerea on cherry had different degrees of resistance to thiophanate-methyl and procymidone.It is necessary to alternate with other types of fungicides while strengthening resistance monitoring to delay the development of resistance.