Widespread distribution of resistance to triazole fungicides in Brazilian populations of the wheat blast pathogen

• DOI: 10.1111/ppa.13288
• Publication Date: 2020-09-30T08:29:59Z
• Authors: Nadia Maria Poloni; Giselle Carvalho; Samara Nunes Camp...; Adriano Francis D...; João Leodato Nune...; Bruce A. McDonald; Silvino Intra Mor...; Nichola Hawkins; Bart A. Fraaije; Diane E. Kelly; Steven L. Kelly; Paulo C. Ceresini
• Keywords: Tebuconazole; Pyricularia; Strobilurin; Azole

Abstract Fungicides have not been effective in controlling the wheat blast disease Brazil. An earlier analysis of 179 isolates Pyricularia oryzae Triticum lineage (PoTl) sampled from fields across six populations central‐southern Brazil during 2012 discovered a high level resistance to strobilurin fungicides. Here we analysed azole same strains based on EC 50 measurements for tebuconazole and epoxiconazole. All Brazilian PoTl exhibited both azoles, with vitro values that were at least 35 times higher than recommended field doses. We sequenced CYP51A CYP51B genes determine if they likely play role observed resistance. Although found five distinct haplotypes carrying four nonsynonymous substitutions , none these correlated elevated . was nine isolates, three each representing low, medium, Both could complement yeast CYP51 function. ‐expressing transformants less sensitive triazoles ones. Transformants expressing haplotype H1 R158K substitution more resistant those H5, which is synonymous H6, triazole‐sensitive P Oryza rice blast. Therefore, reduced triazole sensitivity compared appears be associated non‐target‐site related mechanism acquired after exposure triazoles.