RESUMO
Sclerotinia homoeocarpa causes dollar spot disease on turfgrass and is a serious problem on many species worldwide. Fludioxonil, a phenylpyrrole fungicide, is not currently registered for dollar spot control in China. In this study, the baseline sensitivity to fludioxonil was established using an in vitro assay for 105 isolates of S. homoeocarpa collected from 10 locations in different regions of China. Results indicate that the frequency distribution of effective concentration for 50% inhibition of mycelial growth (EC50) values of the S. homoeocarpa isolates was unimodal (Wâ¯=â¯0.9847, Pâ¯=â¯.2730). The mean EC50 value was 0.0020⯱â¯0.0006⯵g/ml with a range from 0.0003 to 0.0035⯵g/ml. A total of 7 fludioxonil-resistant mutants were obtained in laboratory, the mutants were stable in fludioxonil sensitivity after the 10th transfer, with resistance factor (RF) ranging from 4.320 to >13,901.4. The mutants showed a positive cross-resistance between fludioxonil and the dicarboximide fungicide iprodione, but not propiconazole, fluazinam, and thiophanate-methyl. When mycelial growth rate, pathogenicity and osmotic sensitivity were assessed, the mutants decreased in the fitness compared with their parental isolates. Sequence alignment of the histidine kinase gene Shos1 revealed a 13-bp fragment deletion only in one mutant, no mutations were observed on Shos1 in the rest resistant mutants.
Assuntos
Ascomicetos/efeitos dos fármacos , Ascomicetos/metabolismo , Dioxóis/farmacologia , Fungicidas Industriais/farmacologia , Pirróis/farmacologia , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Aminopiridinas/farmacologia , Ascomicetos/genética , China , Farmacorresistência Fúngica/genética , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Regulação Fúngica da Expressão Gênica/genética , Hidantoínas/farmacologia , Mutação/genética , Tiofanato/farmacologia , Triazóis/farmacologiaRESUMO
Downy mildew disease, caused by the obligate oomycete pathogen Peronospora effusa, is the most important economic constraint for spinach production. Three races (races 12, 13, and 14) of P. effusa have been sequenced and assembled. The draft genomes of these three races have been deposited to GenBank and provide useful resources for dissecting the interaction between the host and the pathogen and may provide a framework for determining the mechanism by which new races of the pathogen are rapidly emerging.