title: Horizontal gene transfer is more frequent with increased heterotrophy and contributes to parasite adaptation.
abstract: Horizontal gene transfer (HGT) is the transfer of genetic material across species boundaries and has been a driving force in prokaryotic evolution. HGT involving eukaryotes appears to be much less frequent, and the functional implications of HGT in eukaryotes are poorly understood. We test the hypothesis that parasitic plants, because of their intimate feeding contacts with host plant tissues, are especially prone to horizontal gene acquisition. We sought evidence of HGTs in transcriptomes of three parasitic members of Orobanchaceae, a plant family containing species spanning the full spectrum of parasitic capabilities, plus the free-livingLindenbergiaFollowing initial phylogenetic detection and an extensive validation procedure, 52 high-confidence horizontal transfer events were detected, often from lineages of known host plants and with an increasing number of HGT events in species with the greatest parasitic dependence. Analyses of intron sequences in putative donor and recipient lineages provide evidence for integration of genomic fragments far more often than retro-processed RNA sequences. Purifying selection predominates in functionally transferred sequences, with a small fraction of adaptively evolving sites. HGT-acquired genes are preferentially expressed in the haustorium-the organ of parasitic plants-and are strongly biased in predicted gene functions, suggesting that expression products of horizontally acquired genes are contributing to the unique adaptive feeding structure of parasitic plants.
authors: Intercollege Graduate Program in Plant Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Department of Biology, The Pennsylvania State University, University Park, PA 16802.|Institute of Molecular Evolutionary Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.
authors: Zhenzhen
authors: Z
authors: Yang
authors: Department of Biology, The Pennsylvania State University, University Park, PA 16802.|Institute of Molecular Evolutionary Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Intercollege Graduate Program in Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.
authors: Yeting
authors: Y
authors: Zhang
authors: Department of Biology, The Pennsylvania State University, University Park, PA 16802.|Institute of Molecular Evolutionary Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.
authors: Eric K
authors: EK
authors: Wafula
authors: Intercollege Graduate Program in Plant Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Department of Biology, The Pennsylvania State University, University Park, PA 16802.|Institute of Molecular Evolutionary Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.
authors: Loren A
authors: LA
authors: Honaas
authors: Department of Biology, The Pennsylvania State University, University Park, PA 16802.
authors: Paula E
authors: PE
authors: Ralph
authors: Intercollege Graduate Program in Plant Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Department of Biology, The Pennsylvania State University, University Park, PA 16802.
authors: Sam
authors: S
authors: Jones
authors: Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.
authors: Christopher R
authors: CR
authors: Clarke
authors: Department of Plant Sciences, University of California, Davis, CA 95616.
authors: Siming
authors: S
authors: Liu
authors: Department of Biology, University of Virginia, Charlottesville, VA 22904.
authors: Chun
authors: C
authors: Su
authors: Intercollege Graduate Program in Plant Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Department of Biology, The Pennsylvania State University, University Park, PA 16802.
authors: Huiting
authors: H
authors: Zhang
authors: Department of Statistics, The Pennsylvania State University, University Park, PA 16802.|Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.
authors: Naomi S
authors: NS
authors: Altman
authors: Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802.
authors: Stephan C
authors: SC
authors: Schuster
authors: Department of Biology, University of Virginia, Charlottesville, VA 22904.
authors: Michael P
authors: MP
authors: Timko
authors: Department of Plant Sciences, University of California, Davis, CA 95616.
authors: John I
authors: JI
authors: Yoder
authors: Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.
authors: James H
authors: http://orcid.org/0000-0001-5127-7294
authors: JH
authors: Westwood
authors: Intercollege Graduate Program in Plant Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802; cwd3@psu.edu.|Department of Biology, The Pennsylvania State University, University Park, PA 16802.|Institute of Molecular Evolutionary Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Intercollege Graduate Program in Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.|Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802.
authors: Claude W
authors: CW
authors: dePamphilis
keywords: HGT; genomic transfer; parasitism; phylogenomics; validation pipeline