Application of a PCR-Luminex System for Molecular Diagnosis of Magnaporthe grisea Isolates Resistant to Dehydratase Inhibitors in Melanin Biosynthesis (MBI-D)

摘要

In Japan, nursery box treatment with MBI-D (melanin biosynthesis inhibitors which target scytalone dehydratase) fungicides, e.g. carpropamid, is a common cultural practice in many rice growing areas as they exhibit long-lasting control efficacy against blast disease caused by Magnaporthe grisea. The treatment is labor-cost effective, and contributes to diminishing the number of fungicide applications in a paddy field. However, in the summer 2001, the efficacy of carpropamid against leaf blast was lost suddenly. Results from extensive studies indicated that resistant strains appeared and played a significant role in the decrease of the fungicide efficacy (Yamaguchi et al., 2002). Subsequently, it was shown that MBI-D resistance was caused by a pointmutation in the gene encoding the targeted protein, which resulted in a single amino acid substitution (V75M) of scytalone dehydratase (Kaku et al., 2003), and a molecular method developed for detecting resistance using primer-introduced restriction enzyme ' analysis PCR (PIRA-PCR).