title: Molecular phylogeny and forms of photosynthesis in tribe Salsoleae (Chenopodiaceae).
abstract: While many C4lineages have Kranz anatomy around individual veins, Salsoleae have evolved the Salsoloid Kranz anatomy where a continuous dual layer of chlorenchyma cells encloses the vascular and water-storage tissue. With the aim of elucidating the evolution of C4photosynthesis in Salsoleae, a broadly sampled molecular phylogeny and anatomical survey was conducted, together with biochemical, microscopic, and physiological analyses of selected photosynthetic types. From analyses of photosynthetic phenotypes, a model for evolution of this form of C4was compared with models for evolution of Kranz anatomy around individual veins. A functionally C3proto-Kranz phenotype (Proto-Kranz Sympegmoid) and intermediates with a photorespiratory pump (Kranz-like Sympegmoid and Kranz-like Salsoloid types) are considered crucial transitional steps towards C4development. The molecular phylogeny provides evidence for C3being the ancestral photosynthetic pathway but there is no phylogenetic evidence for the ancestry of C3-C4intermediacy with respect to C4in Salsoleae. Traits considered advantageous in arid conditions, such as annual life form, central sclerenchyma in leaves, and reduction of surface area, evolved repeatedly in Salsoleae. The recurrent evolution of a green stem cortex taking over photosynthesis in C4clades of Salsoleae concurrent with leaf reduction was probably favoured by the higher productivity of the C4cycle.
authors.affiliation: Botany Department, State Museum of Natural History Stuttgart, Rosenstein 1, D-70191 Stuttgart, Germany.|Centre for Organismal Studies Heidelberg, Biodiversity and Plant Systematics, Heidelberg University, D-69120 Heidelberg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Schüssler
authors.affiliation: Institut für Biologie, Universität Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Freitag
authors.affiliation: Laboratory of Anatomy and Morphology, V. L. Komarov Botanical Institute of Russian Academy of Sciences, Prof. Popov Street 2, 197376, St. Petersburg, Russia.
authors.forename: Nuria
authors.initials: N
authors.lastname: Koteyeva
authors.affiliation: Institute für Allgemeine und Spezielle Botanik und Botanischer Garten der Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany.
authors.forename: Denise
authors.initials: D
authors.lastname: Schmidt
authors.affiliation: School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: Edwards
authors.affiliation: Laboratory of Anatomy and Morphology, V. L. Komarov Botanical Institute of Russian Academy of Sciences, Prof. Popov Street 2, 197376, St. Petersburg, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Voznesenskaya
authors.affiliation: Institute für Allgemeine und Spezielle Botanik und Botanischer Garten der Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany clausing@uni-mainz.de.
authors.forename: Gudrun
authors.identifier: 0000-0003-0094-8769
authors.initials: G
authors.lastname: Kadereit
mesh_terms: D015153:Blotting, Western; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D019663:Chenopodiaceae / Q000201:enzymology / Q000235:genetics* / Q000648:ultrastructure; D050841:Glycine Dehydrogenase (Decarboxylating) / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D010788:Photosynthesis; D010802:Phylogeny; D018515:Plant Leaves / Q000201:enzymology / Q000648:ultrastructure*
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide; D050841:Glycine Dehydrogenase (Decarboxylating)
keywords: Ancestral character state reconstruction; C2 pathway; C3–C4 intermediates; CO2 compensation point; TEM; leaf anatomy; western blots.