Background: Recently, a novel clade Botrytis cinerea group S was found to be common in B. cinerea populations from Germany and New Zealand. Fenhexamid, an effective antibotrytis fungicide, has not been registered in China, but our preliminary study detected fenhexamid-resistant (HydR) isolates from strawberry in Zhejiang Province.
Results: Genetic identification of 639 B. cinerea isolates from strawberry found that 331 (62.9%) belonged to B. cinerea group S. The frequency of HydR isolates ranged from 0 to 37.5% among the nine locations. Of the 74 HydR isolates, 71 were B. cinerea group S and moderately resistant to fenhexamid (HydR). Seven new mutations S9G, P57A, P269L, V365A, E368D, E375K and A378T in the target gene erg27 were reported for the first time. Sixty-two (83.8%) HydR isolates simultaneously carried P57A and A378T mutations, and further transformation assays showed that integration of one copy of erg27(P57A) (,) (A378T) into a wild-type strain led to partial resistance. Detached fruit studies showed that fenhexamid at the recommended field rate could control the disease incited by moderately resistant isolates but not by highly resistant isolates.
Conclusion: B. cinerea group S isolates are widespread in all strawberry-growing locations in Zhejiang Province. The natural HydR populations from strawberry are dominated by B. cinerea group S. © 2015 Society of Chemical Industry.
Keywords: 3-keto reductase (erg27); B. cinerea group S; fenhexamid; grey mould; point mutations.
© 2015 Society of Chemical Industry.