Occurrence of boscalid-resistant Mycovellosiella nattrassii isolates from eggplant and detection using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

Abstract

In 2011, 25 isolates of Mycovellosiella nattrassii causing leaf mold on eggplant were collected from eggplant fields in Kochi Prefecture and tested for sensitivity to the succinate dehydrogenase inhibitor (SDHI) boscalid. In a test to determine the effective fungicide concentration that inhibits mycelia growth 50% relative to the control (EC₅₀), 6 of 25 isolates were less sensitive to boscalid (EC₅₀ > 16 ppm). They were resistant to boscalid but not to pentiopyrad in an inoculation test. A common nucleotide change was found in their SdhB gene encoding a target protein of boscalid, and the mutation was detected by PCR-RFLP.