title: Origin of a novel regulatory module by duplication and degeneration of an ancient plant transcription factor.
abstract: It is commonly believed that gene duplications provide the raw material for morphological evolution. Both the number of genes and size of gene families have increased during the diversification of land plants. Several small proteins that regulate transcription factors have recently been identified in plants, including the LITTLE ZIPPER (ZPR) proteins. ZPRs are post-translational negative regulators, via heterodimerization, of class III Homeodomain Leucine Zipper (C3HDZ) proteins that play a key role in directing plant form and growth. We show that ZPR genes originated as a duplication of a C3HDZ transcription factor paralog in the common ancestor of euphyllophytes (ferns and seed plants). The ZPRs evolved by degenerative mutations resulting in loss all of the C3HDZ functional domains, except the leucine zipper that modulates dimerization. ZPRs represent a novel regulatory module of the C3HDZ network unique to the euphyllophyte lineage, and their origin correlates to a period of rapid morphological changes and increased complexity in land plants. The origin of the ZPRs illustrates the significance of gene duplications in creating developmental complexity during land plant evolution that likely led to morphological evolution.
authors.affiliation: School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Floyd
authors.affiliation: School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Ryan
authors.affiliation: School of Botany, University of Melbourne, Melbourne, Victoria 3010, Australia.
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Conway
authors.affiliation: Department of Biology, New York University, 1009 Silver Center, 100 Washington Square East, New York, NY 10003-6688, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Brenner
authors.affiliation: Department of Plant Science, University of Tennessee, Knoxville, TN 37919, USA.
authors.forename: Kellie P
authors.initials: KP
authors.lastname: Burris
authors.affiliation: Department of Plant Science, University of Tennessee, Knoxville, TN 37919, USA.
authors.forename: Jason N
authors.initials: JN
authors.lastname: Burris
authors.affiliation: Fairy Lake Botanical Garden, Shenzhen & CAS, Guangdong 518004, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Patrick P
authors.initials: PP
authors.lastname: Edger
authors.affiliation: Department of Botany, University of British Columbia, UBC Bot Garden, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Sean W
authors.initials: SW
authors.lastname: Graham
authors.affiliation: Univ Georgia, Dept Plant Biol, Miller Plant Sci, Athens, GA 30602, USA.
authors.forename: James H
authors.initials: JH
authors.lastname: Leebens-Mack
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA.
authors.forename: J Chris
authors.initials: JC
authors.lastname: Pires
authors.affiliation: Department of Zoology, University of British Columbia, #4200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Rothfels
authors.affiliation: Department of Biology, Duke University, Box 90338, Durham, NC 27707, USA.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Sigel
authors.affiliation: New York Bot Garden, Bronx, NY 10458, USA.
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Stevenson
authors.affiliation: Department of Plant Science, University of Tennessee, Knoxville, TN 37919, USA.
authors.forename: C
authors.initials: C
authors.lastname: Neal Stewart
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada; Department of Medicine, University of Alberta, Edmonton, AB T6G 2E1, Canada; BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen 518083, China.
authors.forename: Gane Ka-Shu
authors.initials: GK
authors.lastname: Wong
authors.affiliation: School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia; University of California, Davis, Section of Plant Biology, One Shields Ave., Davis, CA 95616, USA. Electronic address: john.bowman@monash.edu.
authors.forename: John L
authors.initials: JL
authors.lastname: Bowman
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D005075:Biological Evolution; D044002:Bryophyta / Q000235:genetics; D032462:Cycadopsida / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D029624:Ferns / Q000235:genetics; D020440:Gene Duplication; D032501:Huperzia / Q000235:genetics; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D010944:Plants / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D014157:Transcription Factors
keywords: Evolution of development; Gene duplication; Gene family evolution; Homeodomain Leucine Zipper; LITTLE ZIPPER