title: Unique photosynthetic phenotypes in Portulaca (Portulacaceae): C3-C4 intermediates and NAD-ME C4 species with Pilosoid-type Kranz anatomy.
abstract: Portulacaceae is a family that has considerable diversity in photosynthetic phenotypes. It is one of 19 families of terrestrial plants where species having C4photosynthesis have been found. Most species in Portulaca are in the alternate-leaved (AL) lineage, which includes one clade (Cryptopetala) with taxa lacking C4photosynthesis and three clades having C4species (Oleracea, Umbraticola and Pilosa). All three species in the Cryptopetala clade lack Kranz anatomy, the leaves have C3-like carbon isotope composition and they have low levels of C4cycle enzymes. Anatomical, biochemical and physiological analyses show they are all C3-C4intermediates. They have intermediate CO2compensation points, enrichment of organelles in the centripetal position in bundle sheath (BS) cells, with selective localization of glycine decarboxylase in BS mitochondria. In the three C4clades there are differences in Kranz anatomy types and form of malic enzyme (ME) reported to function in C4(NAD-ME versus NADP-ME): Oleracea (Atriplicoid, NAD-ME), Umbraticola (Atriplicoid, NADP-ME) and Pilosa (Pilosoid, NADP-ME). Structural and biochemical analyses were performed on Pilosa clade representatives having Pilosoid-type leaf anatomy with Kranz tissue enclosing individual peripheral vascular bundles and water storage in the center of the leaf. In this clade, all species except P. elatior are NADP-ME-type C4species with grana-deficient BS chloroplasts and grana-enriched M chloroplasts. Surprisingly, P. elatior has BS chloroplasts enriched in grana and NAD-ME-type photosynthesis. The results suggest photosynthetic phenotypes were probably derived from an ancestor with NADP-ME-type C4, with two independent switches to NAD-ME type.
authors.affiliation: Laboratory of Anatomy and Morphology, VL Komarov Botanical Institute of Russian Academy of Sciences, Prof. Popov Street 2, 197376, St. Petersburg, Russia.
authors.forename: Elena V
authors.identifier: 0000-0002-5919-3340
authors.initials: EV
authors.lastname: Voznesenskaya
authors.affiliation: Laboratory of Anatomy and Morphology, VL Komarov Botanical Institute of Russian Academy of Sciences, Prof. Popov Street 2, 197376, St. Petersburg, Russia.
authors.forename: Nuria K
authors.initials: NK
authors.lastname: Koteyeva
authors.affiliation: School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA edwardsg@wsu.edu.
authors.forename: Gerald E
authors.initials: GE
authors.lastname: Edwards
authors.affiliation: Universidad Autónoma de Aguascalientes, Aguascalientes, Mexico.
authors.forename: Gilberto
authors.initials: G
authors.lastname: Ocampo
mesh_terms: D005075:Biological Evolution; D015153:Blotting, Western; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D018548:Cotyledon / Q000033:anatomy & histology; D050841:Glycine Dehydrogenase (Decarboxylating) / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D009243:NAD / Q000378:metabolism; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism* / Q000648:ultrastructure; D031822:Portulaca / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D002247:Carbon Isotopes; D009243:NAD; D002245:Carbon Dioxide; D008291:Malate Dehydrogenase; D050841:Glycine Dehydrogenase (Decarboxylating)
keywords: 
  Portulaca
  ; C3 plants; C3-C4 intermediate; C4 plants; NAD-ME type; NADP-ME type; Portulacaceae.; chloroplast ultrastructure; immunolocalization; photosynthetic enzymes