Widespread Occurrence of a CYP51APseudogene in Calonectria pseudonaviculata

AbstractCalonectria pseudonaviculataand C. henricotiaeare two closely related fungal species responsible for boxwood blight disease of ornamental shrubs (Buxusspp.) in the U.S. and Europe. A previous study has shown isolates of the latter species, which is restricted to Europe, to be less sensitive to tetraconazole, an azole fungicide. In this study, we have analyzed the CYP51paralogs for polymorphism in 26 genomes, representing geographically disparate populations of C. pseudonaviculata(n = 19) and C. henricotiae(n = 7), from the U.S., Europe, Asia, and New Zealand. The presence of a CYP51Apseudogene and lack of a functional CYP51Aparalog in all C. pseudonaviculatagenomes examined is a novel discovery for fungi and could have implications for the evolution of resistance to antifungal chemicals.