Evolution of asexual and sexual reproduction in the aspergilli.

has long-been used as a model organism to gain insights into the genetic basis of asexual and sexual developmental processes both in other members of the genus , and filamentous fungi in general. Paradigms have been established concerning the regulatory mechanisms of conidial development. However, recent studies have shown considerable genome divergence in the fungal kingdom, questioning the general applicability of findings from , and certain longstanding evolutionary theories have been questioned. The phylogenetic distribution of key regulatory elements of asexual reproduction in was investigated in a broad taxonomic range of fungi. This revealed that some proteins were well conserved in the ( AbaA, FlbA, FluG, NsdD, MedA, and some velvet proteins), suggesting similar developmental roles. However, other elements ( BrlA) had a more restricted distribution solely in the , and it appears that the genetic control of sporulation seems to be more complex in the aspergilli than in some other taxonomic groups of the . The evolution of the velvet protein family is discussed based on the history of expansion and contraction events in the early divergent fungi. Heterologous expression of the gene in failed to induce development of complete conidiophores as seen in the aspergilli, but did result in increased conidial production. The absence of many components of the asexual developmental pathway from members of the supports the hypothesis that differences in the complexity of their spore formation is due in part to the increased diversity of the sporulation machinery evident in the Pezizomycotina. Investigations were also made into the evolution of sex and sexuality in the aspergilli. loci were identified from the heterothallic () and () and the homothallic (=). A consistent architecture of the locus was seen in these and other heterothallic aspergilli whereas much variation was seen in the arrangement of loci in homothallic aspergilli. This suggested that it is most likely that the common ancestor of the aspergilli exhibited a heterothallic breeding system. Finally, the supposed prevalence of asexuality in the aspergilli was examined. Investigations were made using as a representative 'asexual' species. It was possible to induce a sexual cycle in given the correct and partners and environmental conditions, with recombination confirmed utilising molecular markers. This indicated that sexual reproduction might be possible in many supposedly asexual aspergilli and beyond, providing general insights into the nature of asexuality in fungi.