title: Comparison of five major trichome regulatory genes in Brassica villosa with orthologues within the Brassicaceae.
abstract: Coding sequences for major trichome regulatory genes, including the positive regulators GLABRA 1(GL1), GLABRA 2 (GL2), ENHANCER OF GLABRA 3 (EGL3), and TRANSPARENT TESTA GLABRA 1 (TTG1) and the negative regulator TRIPTYCHON (TRY), were cloned from wild Brassica villosa, which is characterized by dense trichome coverage over most of the plant. Transcript (FPKM) levels from RNA sequencing indicated much higher expression of the GL2 and TTG1 regulatory genes in B. villosa leaves compared with expression levels of GL1 and EGL3 genes in either B. villosa or the reference genome species, glabrous B. oleracea; however, cotyledon TTG1 expression was high in both species. RNA sequencing and Q-PCR also revealed an unusual expression pattern for the negative regulators TRY and CPC, which were much more highly expressed in trichome-rich B. villosa leaves than in glabrous B. oleracea leaves and in glabrous cotyledons from both species. The B. villosa TRY expression pattern also contrasted with TRY expression patterns in two diploid Brassica species, and with the Arabidopsis model for expression of negative regulators of trichome development. Further unique sequence polymorphisms, protein characteristics, and gene evolution studies highlighted specific amino acids in GL1 and GL2 coding sequences that distinguished glabrous species from hairy species and several variants that were specific for each B. villosa gene. Positive selection was observed for GL1 between hairy and non-hairy plants, and as expected the origin of the four expressed positive trichome regulatory genes in B. villosa was predicted to be from B. oleracea. In particular the unpredicted expression patterns for TRY and CPC in B. villosa suggest additional characterization is needed to determine the function of the expanded families of trichome regulatory genes in more complex polyploid species within the Brassicaceae.
authors.affiliation: Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada; Department of Biology, University of Saskatchewan, Saskatoon SK, Canada.
authors.forename: Naghabushana K
authors.initials: NK
authors.lastname: Nayidu
authors.affiliation: Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada; National Research Council (NRC), Saskatoon SK, Canada.
authors.forename: Sateesh
authors.initials: S
authors.lastname: Kagale
authors.affiliation: Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada.
authors.forename: Ali
authors.initials: A
authors.lastname: Taheri
authors.affiliation: POS Bio-Sciences, Saskatoon, SK, Canada.
authors.forename: Thushan S
authors.initials: TS
authors.lastname: Withana-Gamage
authors.affiliation: Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada.
authors.forename: Isobel A P
authors.initials: IA
authors.lastname: Parkin
authors.affiliation: National Research Council (NRC), Saskatoon SK, Canada.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Sharpe
authors.affiliation: Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada.
authors.forename: Margaret Y
authors.initials: MY
authors.lastname: Gruber
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D001937:Brassica / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D010802:Phylogeny; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology; D064201:Trichomes / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors
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