Rapid detection of benzimidazole resistance in Botrytis cinerea by loop-mediated isothermal amplification

Benzimidazole fungicides (MBCs) have been widely used in agriculture since 1970s, and resistance to this class of fungicides in Botrytis cinerea is reported worldwide. Resistance to MBCs in B. cinerea is related to mutations in the target beta -tubulin gene (TUB2). Compared with the mutation at codon 200, the substitutions from glutamic acid to alanine (E198A), valine (E198V), or lysine (E198K) at codon 198 are currently the predominant mutations in MBC resistant populations of B. cinerea. In this study, a loop-mediated isothermal amplification (LAMP) method was established for rapid detection of benzimidazole resistance in B. cinerea. On the basis of the three mutations at TUB2 codon 198, three sets of LAMP primers were designed, and each of these primer sets was able to specifically amplify the DNA containing its corresponding mutation, while no amplification was detected with other mutated or the wild type DNA. After optimization, the sensitivity and specificity tests illustrated that this LAMP assay had good sensitivity and specificity to detect specific resistant genotypes in B. cinerea. Result also showed that the LAMP assay had good reproducibility. Above all, boiled mycelia could be used as templates, which simplified the process and increased the efficiency of the assay. Considering its rapidity, simplicity, and high efficiency, the LAMP assay developed in this study is a promising tool for the diagnosis of benzimidazole resistance in B. cinerea, and will contribute to the monitoring of resistance development to MBCs in the future.