Horizontal Gene Transfer in Fungi and Its Ecological Importance

Fungi are one of the most diverse kingdoms in the tree of life, thrive in virtually every habitat on the planet, and are vital for a plethora of ecosystems and human-related activities. The advent of genomic technologies has revolutionized the study of fungal ecology and evolution. Surprisingly, evolutionary genomic investigations have revealed that horizontal gene transfer (HGT)—the movement of genetic material from one organism to another by means other than sexual reproduction—is an important factor influencing the ecology and evolution of fungal genomes. This chapter uses an evolutionary framework to discuss the extent and distribution of HGT across fungal ecologies and lifestyles, focusing on some of the best-supported cases to address fundamental questions such as frequencies, barriers, and mechanisms for eukaryotic HGT. One important conclusion that can be drawn from studies of fungal HGT is that HGT rate varies extensively across lineages and that this variation can generally be associated with distinctive ecologies, lifestyles, or genetic backgrounds. Similarly, not all functional categories of genes are equally likely to result in successful transfers. The factors underlying both frequency and functional variations of HGT across fungi are thoroughly discussed. Advances in genomic and synthetic biology technologies will continue to shed light on these questions and bring many other still unanswered questions into focus. Some of these questions and directions for future research are highlighted at the end of this chapter.