Resistance to the fungicide boscalid in laboratory mutants of Botryotinia fuckeliana (Botrytis cinerea) was investigated. The baseline sensitivity to boscalid was evaluated in terms of colony growth (EC50 = 0.3-3 μg ml-1; MIC = 10-30 μg ml-1) and conidial germination (EC50 = 0.03-0.1 μg ml-1; MIC = 1-3 μg ml-1) tests. Mutants were selected in vitro from wild-type strains of the fungus on a fungicide-amended medium containing acetate as a carbon source. Mutants showed two different levels of resistance to boscalid, distinguishable through the conidial germination tests: low (EC50 ~ 0.3 μg ml-1, ranging from 0.03 to 1 μg ml-1; MIC > 100 μg ml-1) and high (EC50 > 100 μg ml-1) resistance. Analysis of meiotic progeny from crosses between resistant mutants and sensitive reference strains showed that resistant phenotypes were due to mutations in single major gene(s) inherited in a Mendelian fashion, and linked with both the Daf1 and Mbc1 genes, responsible for resistance to dicarboximide and benzimidazole fungicides, respectively. Gene sequence analysis of the four sub-units of the boscalid-target protein, the succinate dehydrogenase enzyme, revealed that single or double point mutations in the highly conserved regions of the iron-sulphur protein (Ip) gene were associated with resistance. Mutations resulted in proline to leucine or phenylalanine replacements at position 225 (P225L or P225F) in high resistant mutants, and in a histidine to tyrosine replacement at position 272 (H272Y) in low resistant mutants. Sequences of the flavoprotein and the two transmembrane sub-units of succinate dehydrogenase were never affected.

Selection, characterization and genetic analysis of laboratory mutants of Botryotinia fuckeliana (Botrytis cinerea) resistant to the fungicide boscalid

DE MICCOLIS ANGELINI, RITA MILVIA;Rotolo C;POLLASTRO, Stefania;FARETRA, Francesco
2010-01-01

Abstract

Resistance to the fungicide boscalid in laboratory mutants of Botryotinia fuckeliana (Botrytis cinerea) was investigated. The baseline sensitivity to boscalid was evaluated in terms of colony growth (EC50 = 0.3-3 μg ml-1; MIC = 10-30 μg ml-1) and conidial germination (EC50 = 0.03-0.1 μg ml-1; MIC = 1-3 μg ml-1) tests. Mutants were selected in vitro from wild-type strains of the fungus on a fungicide-amended medium containing acetate as a carbon source. Mutants showed two different levels of resistance to boscalid, distinguishable through the conidial germination tests: low (EC50 ~ 0.3 μg ml-1, ranging from 0.03 to 1 μg ml-1; MIC > 100 μg ml-1) and high (EC50 > 100 μg ml-1) resistance. Analysis of meiotic progeny from crosses between resistant mutants and sensitive reference strains showed that resistant phenotypes were due to mutations in single major gene(s) inherited in a Mendelian fashion, and linked with both the Daf1 and Mbc1 genes, responsible for resistance to dicarboximide and benzimidazole fungicides, respectively. Gene sequence analysis of the four sub-units of the boscalid-target protein, the succinate dehydrogenase enzyme, revealed that single or double point mutations in the highly conserved regions of the iron-sulphur protein (Ip) gene were associated with resistance. Mutations resulted in proline to leucine or phenylalanine replacements at position 225 (P225L or P225F) in high resistant mutants, and in a histidine to tyrosine replacement at position 272 (H272Y) in low resistant mutants. Sequences of the flavoprotein and the two transmembrane sub-units of succinate dehydrogenase were never affected.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11586/127403
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