Fungal sex for strain improvement and disease control

Fungi are highly beneficial to human society, particularly as a source of a tremendous diversity of metabolites encountered in our every-day lives. However, fungi can also be highly detrimental, with long-established and also emerging pathogens posing medical and agricultural problems. From processes as ancient as brewing and cheese-making, to the modern production of pharmacological chemicals such as antibiotics and statins, the production of enzymes for use as lab reagents, and proposed utilisation for biodegradation of plastics, we have long exploited the diverse properties of fungi. Regarding the exploitation of fungi in the biotechnology sectors, there is a long-standing demand for strain improvement for increased economic performance. Strain improvement strategies have classically utilised UV mutagenesis to alter the genetics of strains with the hope of increasing titres of desired products or reducing toxic by-products. However, recent advances in molecular genetics, genome sequencing and bioinformatics have provided opportunities for novel methods of strain improvement. For example, numerous 'silent' gene clusters that are not expressed under standard laboratory conditions have been discovered, whose activation (via techniques of gene manipulation) it is hoped will lead the way to a new wave of metabolite discovery In parallel, sets of genes responsible for sexual reproduction have been discovered in the genomes of a series of fungal species of economic and medical importance, which have traditionally been considered as obligate asexual species. The activation of a sexual cycle in such production organisms would provide a very valuable tool for strain improvement, with considerable benefits over UV mutagenesis and recombinant technologies. For example, this would provide the ability to cross strains with desirable traits and/or the use of the sexual cycle to generate considerable genetic variation as a result of meiosis, thereby allowing for a great diversity of progeny to be screened for increased production of metabolites, or even novel metabolites. Finally, molecular genetic approaches combined with biochemical studies are also revealing aspects of the mechanisms of signalling that trigger and control fungal sexual development.

The initial aims of the current PhD thesis studies are two-fold. Firstly, to build on recent genomic and bioinformatic studies to see if sexual cycles can be established and exploited in previously considered 'asexual' species of economic importance. Secondly, to determine whether hormonal factors and other metabolites involved in fungal morphogenesis might have potential applications in agriculture for novel methods of fungal disease control and pest management.