Deciphering the ecological and evolutionary rules of fungal horizontal gene transfer

Horizontal gene transfer (HGT) is the transfer of genetic material between organisms that are not parent and offspring, and may even be from different species. Unlike traits passed from parent to offspring, HGT lets organisms gain new traits through contact or proximity with another individual. Many examples exist in nature, but the role of HGT in eukaryotes is still debated. In many cases, there is clear evidence that HGT has occurred, but few known mechanisms to explain how or why it happens. This project builds on a recent discovery of a clear HGT mechanism in fungi, a major group of eukaryotes, to answer key questions about how this process works. The work will improve understanding of fungi that affect human, plant, and environmental health. It may also support new advances in evolution and biotechnology, since gene transfer between eukaryotic species could help solve problems in plant breeding, medicine, and drug discovery. In addition, this project will help build the workforce by training early-career researchers, supporting team-based student learning, and expanding mentoring programs. Understanding how species exchange genetic information through HGT is critical for understanding the genetic bases of adaptation. Yet despite its importance for generating adaptive variation, HGT in eukaryotes has been near-impossible to study because the field lacks a system for hypothesis-driven experimentation. This project addresses this knowledge gap by capitalizing on the PI’s ongoing work, which reveals that HGT within fungal eukaryotes is mediated by giant transposons called Starships capable of transferring between species under lab conditions and in nature. The overarching goal of this project is to develop Starships into a model system to experimentally determine the ecological and evolutionary factors affecting fungal HGT. In doing so, the PI will address outstanding questions about the mode and tempo of eukaryotic adaptation with a long-term goal to leverage knowledge of fungal HGT to develop custom transformation-based biotechnologies for eukaryotic systems. This project addresses three independent and complementary Aims using a novel HGT assay: 1) to determine how rates of HGT change in response to diverse environmental cues; 2) to investigate within-species variation in HGT transmitter and receiver abilities and determine the genetic bases of these traits; 3) to test if closer relatives within a model genus transfer genes more often and whether more phylogenetically variable communities facilitate more distant transfers. A reproducible model for studying HGT will benefit systems beyond fungi because it will establish a paradigm for investigating transposon-mediated HGT in other eukaryotes, including plants and animals, and will improve our ability to predict how fast organisms adapt in nature. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2610713 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Emile Gluck-Thaler | Institution: University of Wisconsin-Madison, MADISON, WI | Award Amount: $1,221,287 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2610713 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2610713.html