Complex multicellularity in fungi: the genetic underpinnings of convergent origins

Fungi represent one of the few lineages that evolved complex multicellularity. In contrast to animals, plants, red and brown algae, however, fungi evolved complex multicellular structures convergently, providing a phylogenetically tractable system for understanding the genetic bases of a major evolutionary transition. Fungal fruiting bodies are some of the most typical manifestations of complex multicellularity, with the highest levels of multicellular organization evolved in fungi, comparable to simple animals and plants in terms of complexity levels. To understand the genetic bases of fruiting body development and its evolutionary origins, we apply various computational and high throughput approaches and phylogenetic comparative strategies in the Basidiomycota. Through comparisons of the developmental transcriptomes of 5 Agaricomycete species with diverse morphologies, we could identify conserved and lineage specific genes that show developmentally relevant expression patterns and thus represent candidates for implementing key events of fruiting body development. Complex multicellularity in fungi comprise not only fruiting bodies, but also rhizomorphs, sclerotia and an array of other, mostly reproductive structures. Comparisons of the developmental program of such structures to that of fruiting bodies can highlight some of the general principles of the development of complex multicellular structures in fungi. Such data, combined with whole genome comparisons shed light on the evolution of developmentally relevant genes across fungi and reveal some of the general principles of the evolution of increasingly complex multicellular organisms.