Character transformation and relationships in Corallorhiza (Orchidaceae: Epidendroideae). I. Plastid DNA

Freudenstein, J.V.; Doyle, J.J.

Character transformation and relationships in Corallorhiza (Orchidaceae: Epidendroideae). I. Plastid DNA

1994

Freudenstein, J.V. | Doyle, J.J.

As part of a phylogenetic study of Corallorhiza, a genus of ten species of leafless mycoparasitic orchids, the large single copy region (LSC) and inverted repeat of plastid DNA were examined with restriction fragment analysis to obtain information on relationships among the species, as well as to determine whether structural changes had occurred in the plastome. Deletion areas of between 1.3 and 6.0 kb were detected in the LSC of the C. maculata complex and C. striata, but most of the genome was not significantly affected. Cladistic analysis of restriction site characters produced one most parsimonious tree; additional accessions screened were shown to be most closely related to the primary accession for each species. No synapomorphy was found to unite Corallorhiza. The same topology resulted when deletion characters were added and indicates that deletions in the region of rpo and psa genes have occurred independently in the C. maculata and C. striata groups. Because of the coarse level of resolution in the probing, it is not clear to what extent the genes themselves have been affected. Only one species, the undeleted C. trifida, has been examined physiologically, and it was found to be photosynthetic. This fact, and the deletion pattern, suggest that species of Corallorhiza may show a range of levels of autotrophy.

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