Characterisation of heteroplasmic status at codon 143 of the Botrytis cinerea cytochrome b gene in a semi-quantitative AS-PCR assay.

ABSTRACT

BACKGROUND: An in-depth understanding of quinone outside inhibitor (QoI)-fungicide-resistant Botrytis cinerea isolates in a vineyard is expected to contribute to the development of an optimum disease management programme for the control of grape grey mould. RESULTS: The resistance and structure of the cytochrome b gene in B. cinerea collected from a Japanese vineyard were characterised. The semi-quantitative allele-specific primer-polymerase chain reaction (AS-PCR) assay developed in the present study was able to distinguish heteroplasmic status from homoplasmic status at codon 143 of the cytochrome b gene in QoI-fungicide-resistant B. cinerea from vineyards in Japan. With this assay it was demonstrated that the repeated introduction of QoI fungicide selection pressure increased the ratio of G143A-mutated cytochrome b genes in B. cinerea isolates. CONCLUSION: It is proposed that the semi-quantitative AS-PCR assay is a reliable tool for the detection of QoI fungicide resistance and the evaluation of homoplasmic/heteroplasmic status at codon 143 of the cytochrome b gene in B. cinerea isolates.