title: Extensive horizontal gene transfers between plant pathogenic fungi.
abstract: Horizontal gene transfer (HGT) plays an important role in the adaptation of lineages to changing environments. The extent of this process in eukaryotes, however, remains controversial. The most well-known and dramatic form of HGT represents intracellular gene transfer from endosymbionts to the host nuclear genome. Such episodes of transfer typically involve hundreds of genes and are thought to be possible only in the case of endosymbiosis.
  
  
  
  Using a conservative phylogenomic approach, we analyzed genomic data from the fungal pathogen Magnaporthiopsis incrustans in the order Magnaporthales and identified two instances of exclusive sharing of HGT-derived gene markers between Magnaporthales and another lineage of plant-pathogenic fungi in the genus Colletotrichum. Surprisingly, inspection of these data demonstrated that HGT is far more widespread than anticipated, with more than 90 genes (including 33 highly supported candidates) being putatively transferred between Magnaporthales and Colletotrichum. These gene transfers are often physically linked in the genome and show more than two-fold functional enrichment in carbohydrate activating enzymes associated with plant cell wall degradation.
  
  
  
  Our work provides a novel perspective on the scale of HGT between eukaryotes. These results challenge the notion that recognized HGT plays a minor role in the evolution of fungal lineages, and in the case we describe, is likely implicated in the evolution of plant pathogenesis. More generally, we suggest that the expanding database of closely related eukaryotic genomes and the application of novel analytic methods will further underline the significant impact of foreign gene acquisition across the tree of life. Major lifestyle transitions such as those accompanying the origin of extremophily or pathogenesis are expected to be ideal candidates for studying the mode and tempo of HGT.
authors.affiliation: Department of Ecology, Evolution, and Natural Resources, Rutgers University, Foran Hall, 59 Dudley Road, New Brunswick, New Jersey, 08901, USA. huan.qiu.bio@gmail.com.
authors.forename: Huan
authors.initials: H
authors.lastname: Qiu
authors.affiliation: National Animal Disease Center, USDA, 1920 Dayton Ave, PO Box 70, Ames, Iowa, 50010, USA.
authors.forename: Guohong
authors.initials: G
authors.lastname: Cai
authors.affiliation: Department of Plant Biology and Pathology, Rutgers University, Foran Hall 201, 59 Dudley Road, New Brunswick, New Jersey, 08901, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Luo
authors.affiliation: Department of Ecology, Evolution, and Natural Resources, Rutgers University, Foran Hall, 59 Dudley Road, New Brunswick, New Jersey, 08901, USA.
authors.forename: Debashish
authors.initials: D
authors.lastname: Bhattacharya
authors.affiliation: Department of Plant Biology and Pathology, Rutgers University, Foran Hall 201, 59 Dudley Road, New Brunswick, New Jersey, 08901, USA. zhang@aesop.rutgers.edu.|Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Drive, New Brunswick, New Jersey, 08901, USA. zhang@aesop.rutgers.edu.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
mesh_terms: D001203:Ascomycota / Q000235:genetics*; D020231:Colletotrichum / Q000235:genetics*; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D005819:Genetic Markers; D016681:Genome, Fungal; D054884:Host-Pathogen Interactions; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D010944:Plants / Q000382:microbiology*; D013559:Symbiosis
chemical_list: D005819:Genetic Markers
keywords: Carbohydrate activating enzymes; Colletotrichum; Horizontal gene transfer; Magnaporthales; Pathogenesis