title: Evolutionary dynamics of mating-type loci of Mycosphaerella spp. occurring on banana.
abstract: The devastating Sigatoka disease complex of banana is primarily caused by three closely related heterothallic fungi belonging to the genus Mycosphaerella: M. fijiensis, M. musicola, and M. eumusae. Previous phylogenetic work showing common ancestry led us to analyze the mating-type loci of these Mycosphaerella species occurring on banana. We reasoned that this might provide better insight into the evolutionary history of these species. PCR and chromosome-walking approaches were used to clone the mating-type loci of M. musicola and M. eumusae. Sequences were compared to the published mating-type loci of M. fijiensis and other Mycosphaerella spp., and a novel organization of the MAT loci was found. The mating-type loci of the examined Mycosphaerella species are expanded, containing two additional Mycosphaerella-specific genes in a unique genomic organization. The proteins encoded by these novel genes show a higher interspecies than intraspecies homology. Moreover, M. fijiensis, M. musicola, and M. eumusae contain two additional mating-type-like loci, containing parts of both MAT1-1-1 and MAT1-2-1. The data indicate that M. fijiensis, M. musicola, and M. eumusae share an ancestor in which a fusion event occurred between MAT1-1-1 and MAT1-2-1 sequences and in which additional genes became incorporated into the idiomorph. The new genes incorporated have since then evolved independently in the MAT1-1 and MAT1-2 loci. Thus, these data are an example of the evolutionary dynamics of fungal MAT loci in general and show the great flexibility of the MAT loci of Mycosphaerella species in particular.
authors.affiliation: Evolutionary Phytopathology, CBS-KNAW Fungal Biodiversity Center, Utrecht 3508 AD, The Netherlands.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Arzanlou
authors.forename: Pedro W
authors.initials: PW
authors.lastname: Crous
authors.forename: Lute-Harm
authors.initials: LH
authors.lastname: Zwiers
mesh_terms: D001203:Ascomycota / Q000145:classification / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D005075:Biological Evolution; D049770:Genes, Mating Type, Fungal; D008969:Molecular Sequence Data; D028521:Musa / Q000382:microbiology*; D016366:Open Reading Frames; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid