Species richness and functional groups of angiosperms from the Paraná River Delta region (Argentina)

We provide a checklist of angiosperms collected in the Paraná River Delta Region during the 1990s and early 2000s. Plants were taxonomically identified and classified according to their origin (native/endemic and exotic) and functional group based on their distribution, biological type, morpho-ecology, photosynthetic type and life cycle. A total of 79 families and 375 species were recorded, of which 87.5% were native (46.93% of subtropical-temperate distribution) and 12.5% were exotic (62.72% of temperate distribution). The herbaceous broadleaf and graminoid vegetation predominated in native (76.65%) and exotic (82.35%) species groups. There were only equisetoid herbaceous plants in native species group. Rooted emergent plants and the C3 functional group predominated among native (88.69% and 80.62%, respectively) and exotic (100% in both cases) species groups. Most of the native plants (85.23%) were perennials, while annuals and perennials were equally represented among the exotic species.

Sphingomonas kaistensis sp. nov., a novel alphaproteobacterium containing pufLM genes

Three Gram-negative, non-motile, non-spore-forming short rods (strains PB56T, PB180, PB229) were isolated from soil in South Korea. Cells were orange–red in colour. Strains PB180 and PB229 contained small amounts of bacteriochlorophyll a, which was not detected in strain PB56T. However, all three isolates contained the genes for the photosynthetic type II reaction centre, pufLM. They contained Q-10 as the dominant quinone and C18 : 1 as the dominant fatty acid. The highest 16S rRNA gene sequence similarities were found to Sphingomonas oligophenolica JCM 12082T (95.8 %), Sphingomonas koreensis KCTC 2882T (95.1 %), Sphingomonas mali IFO 15500T (95.1 %), Sphingomonas faeni DSM 14747T (94.8 %), Sphingomonas pruni IFO 15498T (94.7 %) and Sphingomonas aquatilis KCTC 2881T (94.6 %), as well as to Sphingosinicella microcystinivorans Y2T and Sphingosinicella xenopeptidilytica 3-2W4T (95.0–95.2 %). Phylogenetic analyses supported the assignment of strains PB56T, PB180, PB229 to the genus Sphingomonas. The novel isolates differ from all established species of the genus Sphingomonas by their higher G+C content and the absence of straight-chain 2-hydroxy fatty acids. Based on the phylogenetic distances from species with validly published names and their phenotypic properties, the strains constitute a separate species, for which the name Sphingomonas kaistensis sp. nov. is proposed. The type strain is PB56T (=KCTC 12334T=DSM 16846T).

Differential 18O enrichment of leaf cellulose in C3 versus C4 grasses

We show that differences in the oxygen isotope ratio of leaf water between C3 and C4 grasses (five species of each photosynthetic type) become less distinct as relative humidity increases, and that 18O leaf water differences translate directly to the oxygen isotope ratio of leaf cellulose. A conceptual model is presented that is based on grass blade growth characteristics and observed patterns of progressive enrichment in grasses. The Barbour and Farquhar (2000) model was capable of explaining the oxygen isotope ratio of bulk leaf cellulose of C3 and C4 grasses grown under a variety of growth conditions.

LEAF MORPHOLOGY AND CARBON ISOTOPE DISCRIMINATION VALUES IN PURPLE SPURGE (EUPHORBIA PEPLIS L.)

Among the numerous species of the family Euphorbiaceae the photosynthetic carbon fixation follows three pathways: C3, C4, CAM. The object of the present research was Euphorbia peplis L., grown and collected on a Mediterranean coast. Leaf anatomy and ultrastructure together with carbon isotope discrimination measurements indicated that E. peplis is ascribable to the NADP-malic enzyme C4 photosynthetic type.