Evidence for sexuality in the opportunistic fungal pathogen Aspergillus fumigatus.
Aspergillus fumigatus is a medically important opportunistic pathogen and a major cause of respiratory allergy. The species has long been considered an asexual organism. However, genome analysis has revealed the presence of genes associated with sexual reproduction, including a MAT-2 high-mobility group mating-type gene and genes for pheromone production and detection (Galagan et al., personal communication; Nierman et al., personal communication). We now demonstrate that A. fumigatus has other key characteristics of a sexual species. We reveal the existence of isolates containing a complementary MAT-1 alpha box mating-type gene and show that the MAT locus has an idiomorph structure characteristic of heterothallic (obligate sexual outbreeding) fungi. Analysis of 290 worldwide clinical and environmental isolates with a multiplex-PCR assay revealed the presence of MAT1-1 and MAT1-2 genotypes in similar proportions (43% and 57%, respectively). Further population genetic analyses provided evidence of recombination across a global sampling and within North American and European subpopulations. We also show that mating-type, pheromone-precursor, and pheromone-receptor genes are expressed during mycelial growth. These results indicate that A. fumigatus has a recent evolutionary history of sexual recombination and might have the potential for sexual reproduction. The possible presence of a sexual cycle is highly significant for the population biology and disease management of the species.
Paoletti
Mathieu
M
School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
Rydholm
Carla
C
Schwier
Elke U
EU
Anderson
Michael J
MJ
Szakacs
George
G
Lutzoni
François
F
Debeaupuis
Jean-Paul
JP
Latgé
Jean-Paul
JP
Denning
David W
DW
Dyer
Paul S
PS
D000595:Amino Acid Sequence; D001232:Aspergillus fumigatus / Q000235:genetics* / Q000502:physiology*; D001483:Base Sequence; D017931:DNA Primers; D040461:Gene Components; D005800:Genes, Fungal / Q000235:genetics*; D049770:Genes, Mating Type, Fungal; D005828:Genetics, Population; D016681:Genome, Fungal; D023281:Genomics / Q000379:methods; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D012098:Reproduction / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012723:Sex
D017931:DNA Primers