Penicillium chrysogenum is the most ubiquitous filamentous fungus worldwide; however, it is best-known as the major industrial producer of penicillin. It is classified as an asexual ascomycete because there has never been any direct observation of mating or meiosis in the fungus. Significantly, despite its apparent asexuality there is increasing evidence for a latent sexual cycle in P. chrysogenum, similar to what was previously observed for the cryptically-sexual human pathogen Aspergillus fumigatus. Isolates of opposite mating type are found in near-equal proportion in nature and transcriptionally express pheromone and pheromone receptor genes. Furthermore, analysis of the genome sequence has revealed the presence of other key genes required for completion of the sexual cycle. Experiments are in progress to both characterise the functions of the ’master regulator’ mating-type genes and induce a sexual cycle under laboratory conditions. As a first step, a MAT1-1 knockout strain was generated by gene replacement with a phleomycin resistance cassette in a 916;Pcku70 background. Asexual conidiophore development in the mutant strain was affected; it produces significantly higher quantities of conidia relative to the recipient strain P2niaD18, although the ratio of light-to-dark conidial production remains the same. The MAT1-1 gene was also found to play a role in hyphal morphogenesis, with implications for pellet formation in industrial fermentation systems. These results highlight the diverse regulatory roles of the MAT1-1 gene in developmental processes other than sexual reproduction.
Full conference title:
10th EUROPEAN CONFERENCE ON FUNGAL GENETICS
- ECFG 10th (2010)