Cross-kingdom gene transfer facilitates the evolution of virulence in fungal pathogens

The constant interaction between plants and their pathogens has resulted in the evolution of a diverse array of microbial infection strategies. It is increasingly evident that horizontal acquisition of new virulence functions in fungi is one of the evolutionary processes that maintain pathogens' competitive edge over host plants. Genome analyses of fungi are pointing towards this phenomenon being particularly prevalent in the subphylum Pezizomycota. While the extent of cross-kingdom gene transfer can be determined with existing genomic tools and databases, so far very few horizontally transmitted genes have been functionally characterised, and an understanding of their physiological roles in virulence has been determined for even fewer genes. Understanding the evolutionary selection pressures that drive the retention of acquired genes in particular fungal lineages is important, as it will undoubtedly reveal new insights into both fungal virulence mechanisms and corresponding plant defence processes in the future.