Poster Session: Biology of Pathogens - Mycology

29-P

Comparative Genomics in the Boxwood Blight System: Insights into the Global Diversity of the Mating-Type Locus.
M. MALAPI-WIGHT (1), J. Hébert (2), Y. Rivera (3), E. Ismaiel (1), N. Saied (4), B. Gehesquière (5), K. Heungens (5), J. A. Crouch (4)
(1) USDA ARS, Beltsville, MD, U.S.A.; (2) USDA ARS / Rutgers University, Beltsville, MD, U.S.A.; (3) USDA ARS / Rutgers University, BELTSVILLE, MD, U.S.A.; (4) USDA ARS, BELTSVILLE, MD, U.S.A.; (5) Institute for Agricultural and Fisheries Research, Merelbeke, Belgium

The ascomycete Calonectria pseudonaviculata, a destructive fungal pathogen responsible for boxwood blight disease, was first reported in the U.S. in 2011. In a matter of months, North American boxwood blight outbreaks occurred across the eastern seaboard and Pacific Northwest. In order to understand the sexual reproductive potential of C. pseudonaviculata, we have applied next generation sequencing to assess the primary determinant of mating (MAT1) locus. The genome of fifteen C. pseudonaviculata isolates were sequenced, used to create a local BLAST databases in CLC Genomics, and then searched for homologues of the idiomorphic genes MAT1-1 and MAT1-2. Only a single MAT1 idiomorph was identified in each of the fifteen genome assemblies, indicating that C. pseudonaviculata is a heterothallic fungus. Subsequently, we designed specific primers to amplify differently sized regions for each MAT1 locus. Over 200 isolates originating from four continents were analyzed by a duplexed PCR reaction. PCR analyses revealed that the mating types correspond with the genetic lineages G1 and G2. MAT1-2 genotype is globally distributed, but exclusively in the G1 lineage. The MAT1-1 genotype is solely present in five European countries from isolates of the G2 lineage. These results indicate that the fungus is currently unable to sexually reproduce in North America, since all the U.S. isolates belonged to the MAT1-2 genotype.