On the value of nuclear and mitochondrial gene sequences for reconstructing the phylogeny of vanilloid orchids (Vanilloideae, Orchidaceae).
OBJECTIVE
Most molecular phylogenetic studies of Orchidaceae have relied heavily on DNA sequences from the plastid genome. Nuclear and mitochondrial loci have only been superficially examined for their systematic value. Since 40% of the genera within Vanilloideae are achlorophyllous mycoheterotrophs, this is an ideal group of orchids in which to evaluate non-plastid gene sequences.


METHODS
Phylogenetic reconstructions for Vanilloideae were produced using independent and combined data from the nuclear 18S, 5.8S and 26S rDNA genes and the mitochondrial atpA gene and nad1b-c intron.


RESULTS
These new data indicate placements for genera such as Lecanorchis and Galeola, for which plastid gene sequences have been mostly unavailable. Nuclear and mitochondrial parsimony jackknife trees are congruent with each other and previously published trees based solely on plastid data. Because of high rates of sequence divergence among vanilloid orchids, even the short 5.8S rDNA gene provides impressive levels of resolution and support.


CONCLUSIONS
Orchid systematists are encouraged to sequence nuclear and mitochondrial gene regions along with the growing number of plastid loci available.
Cameron
Kenneth M
KM
Department of Botany, University of Wisconsin, Madison, Madison, WI 53706-1381, USA. kmcameron@wisc.edu
D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics*; D050259:Genes, Mitochondrial / Q000235:genetics*; D017343:Genes, Plant; D007438:Introns / Q000235:genetics; D010802:Phylogeny; D012270:Ribosomes / Q000235:genetics; D031669:Vanilla / Q000145:classification* / Q000235:genetics*