Mutations of the β‐tubulin gene fragments from carbendazim‐resistant isolates of Pestalotiopsis sp. causing strawberry leaf blight in Chiang Mai, Thailand

Screening of field isolates of Pestalotiopsis sp. from strawberry leaf blight in Thailand identified 56 carbendazim‐resistant isolates. Of 56 isolates, 39 highly resistant ( HR ) phenotypes grew well on PDA amended with carbendazim even at ≥500 mg/L. Isolates with carbendazim‐resistant phenotype had a conspicuous mutation at particular sites in the beta‐tubulin (β‐tubulin) gene sequence. A β‐tubulin encoding gene from this pathogen was cloned and sequenced. Analysis of the β‐tubulin gene in highly resistant ( HR ) isolates showed a substitution at codon 79 and 102 from serine ( AGT ) to lysine ( AAA ) and valine ( GTA ) to alanine ( GCA ), respectively. The detection of such point mutations in the β‐tubulin gene allows the rapid screening to detect carbendazim‐resistant isolates in the field.