PIRA‐PCR for detection of Fusarium graminearum genotypes with moderate resistance to carbendazim

Abstract

PIRA‐PCR (primer‐introduced restriction analysis PCR) was developed to detect isolates of Fusarium graminearum with moderate resistance to carbendazim, a methyl benzimidazole carbamate (MBC)‐group fungicide. Two primer pairs were designed and synthesized according to the nucleotide sequence of the β2‐tubulin gene from F. graminearum. Fragments of 164 bp were amplified by nested PCR from isolates differing in carbendazim sensitivity. A HindIII restriction enzyme recognition site was introduced artificially by inner primers to detect a mutation at codon 167, and TaaI (Tsp4CI) restriction enzyme was used to detect a mutation at codon 200. The sensitivity of isolates to carbendazim was determined by analyzing electrophoresis patterns of the resulting PCR products after simultaneous digestion with both HindIII and TaaI. Results from PIRA‐PCR and a conventional method (mycelial growth on agar) were identical but PIRA‐PCR required only 7–8 h while the conventional method required 5–7 days. This study demonstrates that PIRA‐PCR not only monitors the appearance of moderately resistant isolates, but can be useful for detecting genotypes of F. graminearum with moderate resistance to carbendazim.