Genomic rearrangements generate hypervariable mini-chromosomes in host-specific isolates of the blast fungus

Supernumerary mini-chromosomes–a unique type of genomic structural variation–have been implicated in the emergence virulence traits plant pathogenic fungi. However, mechanisms that facilitate and maintenance mini-chromosomes across fungi remain poorly understood. In blast fungus Magnaporthe oryzae (Syn. Pyricularia ), have first described early 1990s but, until very recently, overlooked studies. Here we investigated variation four isolates M . from different grass hosts analyzed sequences rice, foxtail millet goosegrass isolates. The these turned out to be highly diverse with distinct sequence composition. They are enriched repetitive elements lower gene density than core-chromosomes. We identified several virulence-related genes mini-chromosome rice isolate, including polyketide synthase Ace1 two variants effector AVR-Pik Macrosynteny analyses around loci revealed rearrangements, inter-chromosomal translocations between core- mini-chromosomes. Our findings provide evidence emerge rearrangements segmental duplication core-chromosomes might contribute adaptive evolution fungus.