Quorum Sensing in Fungi

The most well studied of the more recently identified quorum-sensing molecules in fungi are small primary alcohols, thus chemically different from the acyl-homoserine lactones and modified peptides preferred by bacteria. These primary alcohols include farnesol and tyrosol in Candida albicans, and phenylethanol and tryptophol in Saccharomyces cerevisiae. This chapter talks about molecules after a review of the mating pheromones and a more detailed discussion of the primary alcohol quorum-sensing molecules. In S. cerevisiae, members of the same mitogen-activated protein kinase (MAPK) signaling cascade are involved in both pheromone response and agar invasion in haploid cells, and in Ustilago maydis, the loci expressed in response to mating pheromone contain genes involved in filamentous growth and pathogenicity. This coordination between mating and morphogenesis in fungi is analogous to the connection between competence and virulence in Streptococcus pneumoniae and other gram-positive bacteria, which is also regulated by quorum-sensing peptides. In addition to the mating pheromones and four primary alcohols discussed, there are various examples of quorum-sensing-like phenomena and molecules in the literature, indicating that quorum sensing may indeed be as ubiquitous among fungi as it is among bacteria.