Risk Assessment Of Botrytis Cinerea Resistance To Fludioxonil In Beijing

Gray mold caused by Botrytis cinerea is one of the most important plant disease around the world.Large spotulation quantity,wide ranges of hosts and Rapid genetic variation are the main factors that make it difficult to sustainably control this disease.At present the control of B.cinema mainly dependes on fungicides.It had been repoted that fungicide-resistant genotypes frequently developed around the world.In recent years,the research on multidrug resistance of B.Cinerea has become a research hotspot.Fludioxonil is the novel phenylpyrrole fungicide with the new modes of action to B.cinerea.And it has long efficacy period,broad-spectrum of biological activity,So far it have not been used widely in China.To clarify the status of fludioxonil resistance profile of B.cinerea in Beijing,In this research,the biological activity of fludioxonil against B.cinerea,the sensitivity of B.cinerea to fludioxonil,and its cross-resistance to different fungicides,the biological characteristics of strains which have acquired resistance,and primary drug resistance mechanisms are studied.The main results are listed as follows:(1)A baseline for sensitivity of tomato gray mold to fludioxonil(Botrytis cinerea)was established.The average EC50 value of 90 strains to fludioxonil was(0.1662±0.0096)?g/mL,and the EC50 ranged from 0.0161 to 0.5762 ?g/mL;90%of the strains were selected to establish a sensitive baseline.(2)Successfully obtained 18 domesticated mutants with high resistance to flupronil(all resistance ratio 1000),with a mutation frequency of 20%;The mutants reduced on the mycelial colony rate,sporulation and pathogenicity significantly when compared with that of the parent isolates.After treatment with 1 ?g/mL fludioxonil,the intracellular glycerol content of sensitive strains increased obviously.The linear regression analysis of EC50 value among the different fungicides showed that among fludioxonil,fluazinam,,procymidone,boscalid,pyrimethani,there was no positivelycorrelated cross-resistance.(3)The molecular mechanism of Botrytis cinerea resistant to fludioxonil was preliminary discussed.Sequencing of fludioxonil target gene discovery,all resistant strains had point mutations,and one of the highly resistant strains had a mutation in the HisKA region.,may be a new mutation site(4)Based on the study results mentioned above,we conclude that the resistant level of B.cinerea to fludioxonil was low to medium.