Leaf carbon assimilation and molecular phylogeny in Cattleya species (Orchidaceae)

• Published in: Genetics and molecular research 2009-01, Vol.8 (3), p.976-989
• Main Authors: Andrade-Souza, V, Almeida, A.-A.F, Corrêa, R.X, Costa, M.A, Mielke, M.S, Gomes, F.P
• Format: Article
• Language: English
• Subjects: assimilation (physiology); Biomass; Carbon - metabolism; carbon dioxide; Carbon Dioxide - metabolism; Cattleya; Cattleya aclandiae; Cattleya elongata; Cattleya guttata; Cattleya kerrii; Cattleya schilleriana; Cattleya silvana; Cattleya tenuis; Cattleya tigrina; Cattleya warneri; Crassulacean acid metabolism; gas exchange; genetic variation; Hadrolaelia grandis; Hadrolaelia purpurata; leaf area; maximum parsimony method; maximum quantum yield; molecular systematics; neighbor joining analysis; Orchidaceae; Orchidaceae - genetics; Orchidaceae - metabolism; Photosynthesis; photosynthetic photon flux density; photosystem II; Phylogeny; Plant Leaves - genetics; Plant Leaves - metabolism; rain forests
• ISSN: 1676-5680; 1676-5680
• DOI: 10.4238/vol8-3gmr618

We examined leaf CO(2) assimilation and how it varied among species within the orchid genus Cattleya. Measurements of CO(2) assimilation and maximum quantum yield of PS II (Fv/Fm) were made for mature leaves of nine species using a portable system for photosynthesis measurement and a portable fluorometer. Leaf area was measured with an area meter, and the specific leaf mass was determined. DNA of nine Cattleya species and two species of Hadrolaelia was extracted using the CTAB protocol. Each sample was amplified and sequenced using primers for the trnL gene. The phylogenetic analyses, using neighbor-joining and maximum parsimony methods, retrieved a group that included Cattleya and Hadrolaelia species, in which the unifoliate species were separated from the bifoliates. The topologies of the two cladograms showed some similarities. However, C. guttata (bifoliate) was placed in the unifoliate clade in the neighbor-joining tree, while C. warneri (unifoliate) was not placed in this clade in the maximum parsimony tree. Most Cattleya species keep the leaf stomata closed from 6 am to 4 pm. We suggest that C. elongata, C. tigrina and C. tenuis have C(3)-crassulacean acid metabolism since they open their stomata around 12 am. The Fv/Fm values remained relatively constant during the measurements of CO(2) assimilation. The same was observed for the specific leaf mass values, although great variations were found in the leaf area values. When the species were grouped using molecular data in the neighbor-joining analysis, no relation was observed with CO(2) assimilation.