Resistance risk for tebuconazole against Sclerotinia sclerotiorum
In order to identify the risk of tebuconazole resistance of Sclerotinia sclerotiorum,susceptibility base-line of 119 strains of S.sclerotiorum to tebuconazole was established by growth rate method,and two resistant strains were obtained by UV induction combined with drug screening.Genetic stability of resistance,mycelial growth rate,sclerotinia production ability,pathogenicity,sequence analysis and expression measurement of target gene of resis-tant strains were studied.Results showed that EC50 values of all strains ranged from 0.0121 to 0.8907 µg/mL,with an average of 0.2403±0.1365 µg/mL,showing a unimodal curve distribution.No field resistant strains were detect-ed.Two resistant strains 19AH-5A and 19AH-5C were obtained by indoor induction,and their EC50 values of tebu-conazole were increased by 5.857 and 12.903 times,respectively.In addition,the biological characteristics of 19AH-5C strain were not significantly different from those of susceptive strain,while the pathogenicity of 19AH-5A was seriously degraded.The sequence of CYP51 gene encoding the target protein of tebuconazole in the two re-sistant strains were completely consistent with that in susceptive strain,and no base mutation resulting in amino ac-id change was found.However,the relative expression of CYP51 gene in the resistant strain 19AH-5C was signifi-cantly up-regulated by 3.72 times in condition treated with tebuconazole.Under the selective pressure of tebucon-azole,it was suggested that S.sclerotiorum had a moderate resistance risk to tebuconazole.Therefore,when using te-buconazole to control S.sclerotiorum,resistance level of the pathogen is recommended to be monitored continuously,and fungicides of different action mode could be used alternately in rapeseed production to delay the occurrence of fungicide resistance in fields.
万方数据
维普
