The Complete Plastid Genome of Neottia bifolia (Raf.) Baumbach (Orchidaceae): Insights Into Chlorophyllous and Achlorophyllous Plastid Genomes

Neottia bifolia is a small, terrestrial orchid distributed across the southeastern United States and northward up the Atlantic coast into Canada. The genus is well-studied as a model for the evolution of mycoheterotrophy, having both chlorophyllous and putatively achlorophyllous taxa. Despite this, the photosynthetic species, N. bifolia is relatively understudied. We provide results from the sequencing, assembly, and annotation of the complete plastid genome of N. bifolia and examine some evolutionary trends in the genus, using the 10 additional complete Neottia plastid genomes available on GenBank. We find that the plastid genome of N. bifolia is 156,533 base pairs in length with 130 protein-coding genes, including 38 tRNA genes and eight rRNA genes. We find a similar number of rRNAs and tRNAs across the genus, but significantly fewer protein coding genes and an overall smaller plastid genome size in the mycoheterotrophic species. We find support for the monophyly of the mycoheterotrophic species. The placement of N. bifolia varies slightly between inferences, but the species is most frequently placed in a clade with Neottia cordata, Neottia japonica, and Neottia suzuki.