title: Shared characteristics underpinning C4 leaf maturation derived from analysis of multiple C3 and C4 species of Flaveria.
abstract: Most terrestrial plants use C3photosynthesis to fix carbon. In multiple plant lineages a modified system known as C4photosynthesis has evolved. To better understand the molecular patterns associated with induction of C4photosynthesis, the genus Flaveria that contains C3and C4species was used. A base to tip maturation gradient of leaf anatomy was defined, and RNA sequencing was undertaken along this gradient for two C3and two C4Flaveria species. Key C4traits including vein density, mesophyll and bundle sheath cross-sectional area, chloroplast ultrastructure, and abundance of transcripts encoding proteins of C4photosynthesis were quantified. Candidate genes underlying each of these C4characteristics were identified. Principal components analysis indicated that leaf maturation and the photosynthetic pathway were responsible for the greatest amount of variation in transcript abundance. Photosynthesis genes were over-represented for a prolonged period in the C4species. Through comparison with publicly available data sets, we identify a small number of transcriptional regulators that have been up-regulated in diverse C4species. The analysis identifies similar patterns of expression in independent C4lineages and so indicates that the complex C4pathway is associated with parallel as well as convergent evolution.
authors.affiliation: Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge CB2 3EA, UK.
authors.forename: Britta M C
authors.identifier: 0000-0001-9931-6985
authors.initials: BM
authors.lastname: Kümpers
authors.affiliation: Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge CB2 3EA, UK.
authors.forename: Steven J
authors.identifier: 0000-0003-2353-7794
authors.initials: SJ
authors.lastname: Burgess
authors.affiliation: Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge CB2 3EA, UK.
authors.forename: Ivan
authors.identifier: 0000-0001-7964-7306
authors.initials: I
authors.lastname: Reyna-Llorens
authors.affiliation: Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge CB2 3EA, UK.
authors.forename: Richard
authors.identifier: 0000-0001-8721-7197
authors.initials: R
authors.lastname: Smith-Unna
authors.affiliation: Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge CB2 3EA, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Boursnell
authors.affiliation: Department of Plant Sciences, Downing Street, University of Cambridge, Cambridge CB2 3EA, UK jmh65@cam.ac.uk.
authors.forename: Julian M
authors.identifier: 0000-0003-0662-7958
authors.initials: JM
authors.lastname: Hibberd
mesh_terms: D002736:Chloroplasts / Q000502:physiology / Q000648:ultrastructure; D037142:Flaveria / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D017343:Genes, Plant; D010788:Photosynthesis; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism*; D025341:Principal Component Analysis
keywords: 
  Flaveria
  ; C4 leaf anatomy; C4 photosynthesis; RNA-seq.; convergent evolution; gene expression; parallel evolution