The complete annotated plastome sequences of six genera in the tropical woody Polygonaceae.

BACKGROUND: The Polygonaceae is a family well-known for its weeds, and edible plants, Fagopyrum (buckwheat) and Rheum (rhubarb), which are primarily herbaceous and temperate in distribution. Yet, the family also contains a number of lineages that are principally distributed in the tropics and subtropics. Notably, these lineages are woody, unlike their temperate relatives. To date, full-genome sequencing has focused on the temperate and herbaceous taxa. In an effort to increase breadth of genetic knowledge of the Polygonaceae, we here present six fully assembled and annotated chloroplast genomes from six of the tropical, woody genera: Coccoloba rugosa (a narrow and endangered Puerto Rican endemic), Gymnopodium floribundum, Neomillspaughia emarginata, Podopterus mexicanus, Ruprechtia coriacea, and Triplaris cumingiana. RESULTS: These assemblies represent the first publicly-available assembled and annotated plastomes for the genera Podopterus, Gymnopodium, and Neomillspaughia, and the first assembled and annotated plastomes for the species Coccoloba rugosa, Ruprechtia coriacea, and Triplaris cumingiana. We found the assembled chloroplast genomes to be above the median size of Polygonaceae plastomes, but otherwise exhibit features typical of the family. The features of greatest sequence variation are found among the ndh genes and in the small single copy (SSC) region of the plastome. The inverted repeats show high GC content and little sequence variation across genera. When placed in a phylogenetic context, our sequences were resolved within the Eriogonoideae. CONCLUSIONS: These six plastomes from among the tropical woody Polygonaceae appear typical within the family. The plastome assembly of Ruprechtia coriacea presented here calls into question the sequence identity of a previously published plastome assembly of R. albida.

A plastome phylogeny of Rumex (Polygonaceae) illuminates the divergent evolutionary histories of docks and sorrels.

The genus Rumex L. (Polygonaceae) provides a unique system for investigating the evolutionary development of sex determination and molecular rate evolution. Historically, Rumex has been divided, both taxonomically and colloquially into two groups: 'docks' and 'sorrels'. A well-resolved phylogeny can help evaluate a genetic basis for this division. Here we present a plastome phylogeny for 34 species of Rumex, inferred using maximum likelihood criteria. The historical 'docks' (Rumex subgenus Rumex) were resolved as monophyletic. The historical 'sorrels' (Rumex subgenera Acetosa and Acetosella) were resolved together, though not monophyletic due to the inclusion of R. bucephalophorus (Rumex subgenus Platypodium). Emex is supported as its own subgenus within Rumex, instead of resolved as sister taxa. We found remarkably low nucleotide diversity among the docks, consistent with recent diversification in that group, especially as compared to the sorrels. Fossil calibration of the phylogeny suggested that the common ancestor for Rumex (including Emex) has origins in the lower Miocene (22.13 MYA). The sorrels appear to have subsequently diversified at a relatively constant rate. The origin of the docks, however, was placed in the upper Miocene, but with most speciation occurring in the Plio-Pleistocene.