Study On Resistance And Molecular Mechanism Of Imazalil In PenicUlium Digitatum

A large number of isolates of P.digitatum was collected from the fruit wholesale market of Hangzhou and citrus sales , the susceptibilities of some isolates among them to imazalil had been tested The result showed , there were differences in the imazalil susceptibilities among eight isolates, and the imgzall resistant isolates of P.digitatum were found. The study of mutal resistance to different SBIs show:These isolates which were resistant to imazatil will have positive cross resistance to prochloraz^usilazole,triadimefon. Results of study on fitness of the different resistant isolates found,that pathogenicity of the resistant isolates dropped obviously compared with sensitive ones, the mycelium growth ability and the ascospores germinabUity of the resistant isolates were slightly lower than those of the sensitive ones.The 14-a-demethylation genes (CPY51) of Penecillium degitatwn were amplified by polymerase chain reaction (PCR) from one imazalil-senstive (Pd23) and two imazalil-resistant (PdOl and PdOT) isolates, and cloned to T-Easy Vector. Sequence analysis indicated that Pd23CYP51 (imazalil-senstive) is 2082bp long with one ORF, which is interrupted by three introns, and ecoded 516aa. The gene organization of bom PMJCYP51 and PdOTCKPJ/, two imazalil-resistance isolates are 2586bp, and with the same structural genes ofPd23CYP5L However, in the upstream ofPdOlCYPSl and Pd07CKP57, a unique 126bp sequence was tandemly repeated five times and was presented only once in Pd23CYP51. Additionally, the animo acid on 208,308 and 437 ofPd23CYP51, which were Gly, Tyr and His, respectively, was replaced by Ala, His and Tyr in PdOlCYPSl and P607CYP5. However, as for the relation with imazalil resistance, a unique 126bp sequencetandemly repeated and several pieces of amino acid replacing , which will be got further verification by the CYP51 gene sequence comparations of strains with the different imazalil sensitivities ,and the expressing difference of the CYP5I gene ,and the heredity and transformation of fungi.