Research Article

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

Published: August 11, 2009
Genet. Mol. Res. 8 (3) : 976-989 DOI: https://doi.org/10.4238/vol8-3gmr618
Cite this Article:
(2009). Leaf carbon assimilation and molecular phylogeny in Cattleya species (Orchidaceae). Genet. Mol. Res. 8(3): gmr618. https://doi.org/10.4238/vol8-3gmr618
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Abstract

We examined leaf CO2 assimilation and how it varied among species within the orchid genus Cattleya. Measurements of CO2 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 C3-crassu­lacean acid metabolism since they open their stomata around 12 am. The Fv/Fm values remained relatively constant during the measurements of CO2 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 CO2 assimilation.

We examined leaf CO2 assimilation and how it varied among species within the orchid genus Cattleya. Measurements of CO2 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 C3-crassu­lacean acid metabolism since they open their stomata around 12 am. The Fv/Fm values remained relatively constant during the measurements of CO2 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 CO2 assimilation.