Present address: Discovery Biology, Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN 46268, USA.
Identification of the mutation responsible for resistance to QoI fungicides and its detection in Ascochyta rabiei (teleomorph Didymella rabiei)
Article first published online: 2 AUG 2012
© 2012 The Authors. Plant Pathology © 2012 BSPP
Volume 62, Issue 3, pages 688–697, June 2013
How to Cite
Delgado, J. A., Lynnes, T. C., Meinhardt, S. W., Wise, K. A., Gudmestad, N. C., Bradley, C. A., Markell, S. G. and Goswami, R. S. (2013), Identification of the mutation responsible for resistance to QoI fungicides and its detection in Ascochyta rabiei (teleomorph Didymella rabiei). Plant Pathology, 62: 688–697. doi: 10.1111/j.1365-3059.2012.02661.x
- Issue published online: 22 APR 2013
- Article first published online: 2 AUG 2012
- fungicide resistance;
- G143A mutation;
- mismatch amplification mutation assay;
- molecular diagnosis
This study characterized a fragment of the cytochrome b gene from Ascochyta rabiei isolates collected in North Dakota, USA, that varied in sensitivity to quinone-outside inhibitor (QoI) fungicides. The sequenced genomic DNA fragment contained a group I intron immediately after codon 131. The size of the cytochrome b gene was estimated to be over 4·6 kb. Multiple alignment analysis of cDNA and protein sequences revealed a mutation that changed the codon for amino acid 143 from GGT to GCT, introducing an amino acid substitution from glycine to alanine (G143A), which is frequently associated with QoI resistance. Based on this mutation, a diagnostic PCR assay was developed using an approach called mismatch amplification mutation assay. This method was successfully validated by testing a total of 70 A. rabiei isolates, of which 38 isolates were found to be QoI-resistant. This fast and accurate PCR assay provides a very useful and simple screening method for QoI resistance in A. rabiei isolates.