油菜菌核病菌对多菌灵和乙霉威的抗药性机理

生物测定结果表明,油菜菌核病菌田间菌株对多菌灵(MBC)敏感性表型呈多样性,即存在MBCS、MBCLRLR、MBCHRHR和MBCVHR表型.而对乙霉威(DIE)则只检测到DIES和DIEHR表型.MBCS、MBCLR和MBCHR菌株中除JD2-3菌株为DIES外,其余菌株均为DIEHR,MBCVHR菌株对DIE表现为DIES.MBC和DIE之间存在典型的负相关交互抗性.序列分析结果表明,表型为MBCVHRDIES菌株的β-微管蛋白基因,第198位氨基酸由Glu(GAG)突变为Ala(GCG);表型为MBCHRDIEHR菌株的β-微管蛋白基因的突变位点在第200位,由Phe(TTC)突变为Tyr(TAC);而表型为MBCSDIES和MBCLRDIEHR的菌株在所扩增的β-微管蛋白基因片段中未发生突变.初步表明,β-微管蛋白基因198和200位氨基酸的突变是引起油菜菌核病菌对多菌灵抗药性呈多样性的分子机理.

Mechanism of resistance of Sclerotinia sclerotiorum to carbendazim and diethofencarb

4881 field isolates of Sclerotinia sclerotiorum from Jiangsu Province were detected with bioassay method.The results indicated that the phenotypes sensitive to carbendazim(MBC) were diversified:isolates which failed to grow on media treated with 0.5 mg/L MBC(MIC<0.5 mg/L) were considered sensitive(MBC).Resistant isolates were divided into three phenotypes; low resistance(MBCLR),growth of the isolates on media contaning 0.5 mg/ L MBC but not on that containing 5 mg/L MBC(5mg/L > MIC>0.5 mg/L) ; high resistance(MBCHR),good growth on media containing up to 50 mg/L MBC but not on that containing 500 mg/L MBC(500 mg/L >MIC>50 mg/L) ; and very high resistance(MBCVHR),good growth on media with 500 mg/L MBC(MIC >500 mg/L) but not on that with 0.5 mg/L DIE.No transitive phenotypes were detected between DIES,which failed to grow on media with 0.5 mg/L DIE(MIC <0.5 mg/L) and DIEHR,good grow on media with 50 mg/L DIE(MIC >50 mg/L).MBCS,MBC and MBCHR isolates were insensitive to DIE except one isolate,JD2-3.MBCVHR isolates were all sensitive to DIE.Negatively correlated cross resistance(NCCR) was manifested between carbendazim and diethofencarb.Nucleotide sequence analysis revealed point mutation in the beta-tubulin gene of carbendazim-resistant strains of Sclerotinia sclerotiorum.Codon 198 for Glutaminc acid(encode by GAG) was altered to Alanine(encode by GCG) in phenotypes sensitive strain of MBCVHRDIES;and codon 200 for Phenylalanine(encode by TTC) altered to Tyrosine(encode by TAC) in phenotypes sensitive strains of MBCHR DIE.No point mutation were taken place in phenotypes sensitive strains of MBC DIE and MBCLRDIEHR.Mutation in 198 and 200 codon of beta-tubulin was the molecular mechanism of diversity carbendazim-resistant of Sclerotinia sclerotiorum.