Phenotypic and genetic characterization of Chilean isolates of Botrytis cinerea with different levels of sensitivity to fenhexamid
Résumé
Forty three Chilean Botrytis einerea isolates of different fenhexamid sensitivities, obtained from table grapes, were phenotypically analyzed and sequenced for the erg27 gene that encodes the 3-ketoreductase enzyme. Fifteen isolates were highly resistant to fenhexamid (HydR3(+)) with conidial germination EC50 values >5 mu g.mL(-1) and colony growth EC50 values >2 mu g.mL(-1). Five isolates had slight to moderate resistance levels (HydR3(-)) with conidial germination EC50 values between 0.7 and 2.6 mu g.mL(-1) and colony growth EC50 values between 0.4 and 3 mu g.mL(-1). Twenty-three isolates were fenhexamid sensitive (HydS) (conidial germination and colony growth EC50 values < 0.1 mu gmL(-1)). Resistance to anilinopyrimidine (phenotype AniR1), benzimid azole (phenotype BenR1) and dicarboximide fungicides (phenotype ImiR1) was common among isolates tested. When HydR3(-) and HydR3(+) sequences were compared with fenhexamid-resistant French isolates, it was verified that all the HydR3(+) had a modification in the C-terminal at position 412 of the protein, close to the putative transmembrane domain responsible for fenhexamid resistance. The HydR3- isolates showed six specific amino acid changes in the sequenced region of the erg27 gene, between positions 199 and 408 of the protein, with three of these described for the first time.