title: Evolution of C4 photosynthesis in the genus flaveria: establishment of a photorespiratory CO2 pump.
abstract: C4 photosynthesis is nature's most efficient answer to the dual activity of ribulose-1,5-bisphosphate carboxylase/oxygenase and the resulting loss of CO(2) by photorespiration. Gly decarboxylase (GDC) is the key component of photorespiratory CO(2) release in plants and is active in all photosynthetic tissues of C(3) plants, but only in the bundle sheath cells of C(4) plants. The restriction of GDC to the bundle sheath is assumed to be an essential and early step in the evolution of C(4) photosynthesis, leading to a photorespiratory CO(2) concentrating mechanism. In this study, we analyzed how the P-protein of GDC (GLDP) became restricted to the bundle sheath during the transition from C(3) to C(4) photosynthesis in the genus Flaveria. We found that C(3) Flaveria species already contain a bundle sheath-expressed GLDP gene in addition to a ubiquitously expressed second gene, which became a pseudogene in C(4) Flaveria species. Analyses of C(3)-C(4) intermediate Flaveria species revealed that the photorespiratory CO(2) pump was not established in one single step, but gradually. The knowledge gained by this study sheds light on the early steps in C(4) evolution.
authors.affiliation: Heinrich-Heine-Universität, Department Biologie, 40225 Duesseldorf, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Schulze
authors.forename: Julia
authors.initials: J
authors.lastname: Mallmann
authors.forename: Janet
authors.initials: J
authors.lastname: Burscheidt
authors.forename: Maria
authors.initials: M
authors.lastname: Koczor
authors.forename: Monika
authors.initials: M
authors.lastname: Streubel
authors.forename: Hermann
authors.initials: H
authors.lastname: Bauwe
authors.forename: Udo
authors.initials: U
authors.lastname: Gowik
authors.forename: Peter
authors.initials: P
authors.lastname: Westhoff
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D019143:Evolution, Molecular; D037142:Flaveria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D050841:Glycine Dehydrogenase (Decarboxylating) / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010101:Oxygen Consumption / Q000528:radiation effects; D010788:Photosynthesis; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D002245:Carbon Dioxide; D050841:Glycine Dehydrogenase (Decarboxylating); D012273:Ribulose-Bisphosphate Carboxylase