title: Transcriptomes of the parasitic plant family Orobanchaceae reveal surprising conservation of chlorophyll synthesis.
abstract: Parasitism in flowering plants has evolved at least 11 times [1]. Only one family, Orobanchaceae, comprises all major nutritional types of parasites: facultative, hemiparasitic (partially photosynthetic), and holoparasitic (nonphotosynthetic) [2]. Additionally, the family includes Lindenbergia, a nonparasitic genus sister to all parasitic Orobanchaceae [3-6]. Parasitic Orobanchaceae include species with severe economic impacts: Striga (witchweed), for example, affects over 50 million hectares of crops in sub-Saharan Africa, causing more than $3 billion in damage annually [7]. Although gene losses and increased substitution rates have been characterized for parasitic plant plastid genomes [5, 8-11], the nuclear genome and transcriptome remain largely unexplored. The Parasitic Plant Genome Project (PPGP; http://ppgp.huck.psu.edu/) [2] is leveraging the natural variation in Orobanchaceae to explore the evolution and genomic consequences of parasitism in plants through a massive transcriptome and gene discovery project involving Triphysaria versicolor (facultative hemiparasite), Striga hermonthica (obligate hemiparasite), and Phelipanche aegyptiaca (Orobanche [12]; holoparasite). Here we present the first set of large-scale genomic resources for parasitic plant comparative biology. Transcriptomes of above-ground tissues reveal that, in addition to the predictable loss of photosynthesis-related gene expression in P. aegyptiaca, the nonphotosynthetic parasite retains an intact, expressed, and selectively constrained chlorophyll synthesis pathway.
authors.affiliation: Department of Biology, Institute of Molecular Evolutionary Genetics, and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA. nwickett@chicagobotanic.org
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Wickett
authors.forename: Loren A
authors.initials: LA
authors.lastname: Honaas
authors.forename: Eric K
authors.initials: EK
authors.lastname: Wafula
authors.forename: Malay
authors.initials: M
authors.lastname: Das
authors.forename: Kan
authors.initials: K
authors.lastname: Huang
authors.forename: Biao
authors.initials: B
authors.lastname: Wu
authors.forename: Lena
authors.initials: L
authors.lastname: Landherr
authors.forename: Michael P
authors.initials: MP
authors.lastname: Timko
authors.forename: John
authors.initials: J
authors.lastname: Yoder
authors.forename: James H
authors.initials: JH
authors.lastname: Westwood
authors.forename: Claude W
authors.initials: CW
authors.lastname: dePamphilis
mesh_terms: D005075:Biological Evolution; D002734:Chlorophyll / Q000235:genetics*; D020224:Expressed Sequence Tags; D017343:Genes, Plant; D008969:Molecular Sequence Data; D031670:Orobanchaceae / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D010788:Photosynthesis; D010802:Phylogeny; D018520:Plant Shoots / Q000235:genetics / Q000502:physiology; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013559:Symbiosis; D059467:Transcriptome
chemical_list: D002734:Chlorophyll