Mutation at codon 198 of Tub2 gene for carbendazim resistance in colletotrichum gloeosporioides causing mango anthracnose in Thailand

Abstract

Screening of field isolates of Colletotrichum gloeosporioides from various mango cultivars from markets and orchards in Thailand identified 113 carbendazim-resistant isolates. Isolates with a highly-resistant phenotype (HR) grew well on Potato Dextrose Agar (PDA) amended with carbendazim even at ≥500 mg/l. Isolates with carbendazim-resistant phenotype had a conspicuous mutation at a particular site in the β-tubulin (TUB2) gene sequence. The sequence of TUB2 in HR isolates showed a single nucleotide transversion of adenine to cytosine, resulting in a substitution at codon 198 from glutamic acid (GAG) in wild type to alanine (GCG) in HR isolates. This is the first report of the molecular determination of field isolates for benzimidazole fungicide resistance in Southeast Asia in C. gloeosporioides causing mango anthracnose.