Mechanisms of Resistance to an Azole Fungicide in the Grapevine Powdery Mildew Fungus, Erysiphe necator

• DOI: 10.1094/phyto-07-14-0202-r
• Publication Date: 2014-10-01T16:54:20Z
• Authors: Omer Frenkel; Lance Cadle-Davidson; Wayne F. Wilcox; Michael G. Milgroom
• Keywords: Efflux; Azole; Blumeria graminis; Demethylase

We studied the mechanisms of azole resistance in Erysiphe necator by quantifying sensitivity to myclobutanil (EC50) 65 isolates from eastern United States and 12 Chile. From each isolate, we sequenced gene for sterol 14α-demethylase (CYP51), measured expression CYP51 homologs four putative efflux transporter genes, which identified E. transcriptome. Sequence variation was relatively low, with sequences 40 U.S. identical reference sequence. Nine five Chile carried a previously A T nucleotide substitution position 495 (A495T), results an amino acid codon 136 (Y136F) correlates high levels resistance. also found 1119 (A1119C) 15 isolates, whose mean EC50 value equivalent that Y136F isolates. Isolates carrying mutation A1119C had significantly greater expression, even though does not affect Regression analysis showed no significant effects genes on EC50. Both increased appear responsible populations necator.