Relationships of North American members of Rhodiola (Crassulaceae)

Abstract

Taxa of Rhodiola L. (Crassulaceae) generally grow in arctic or alpine habitats. Some Rhodiola species are used medicinally, one taxon, Rhodiola integrifolia Raf. subsp. leedyi (Rosend. & J.W.Moore) Moran, (Leedy's roseroot), is rare and endangered, and the group's biogeography in North America is intriguing because of distributional disjunctions and the possibility that Rhodiola rhodantha (A.Gray) H.Jacobsen (2n = 7 II ) and Rhodiola rosea L. (2n = 11 II ) hybridized to form Rhodiola integrifolia Raf. (2n = 18 II ). Recent studies of the North American Rhodiola suggest that the group's current taxonomy is misleading. We analyzed nuclear and chloroplast DNA sequences (internal transcribed spacer (ITS), trnL intron, trnL-trnF spacer, trnS-trnG spacer) from the North American Rhodiola taxa. We combined our data with GenBank sequences from Asian Rhodiola species, performed parsimony, maximum likelihood (ML), and Bayesian phylogenetic analyses, and applied a Bayesian clock model to the ITS data. Our analyses reveal two major Rhodiola clades, suggest that hybridization between R. rhodantha and R. rosea lineages was possible, show two distinct clades within R. integrifolia, and demonstrate that a Black Hills, South Dakota, Rhodiola population should be reclassified as Leedy's roseroot. We recommend that R. integrifolia be revised, and that the Black Hills Leedy's roseroot population be managed as part of that rare and endangered taxon. Résumé : Le taxon des Rhodiola L. (Crassulaceae) croît normalement dans des habitats arctiques ou alpins. Certaines espèces de Rhodiola sont utilisées comme plantes médicinales et un taxon, Rhodiola integrifolia Raf. subsp. leedyi (Rosend. & J.W.Moore) Moran, (orpin de Leedy), est rare et menacé. La biogéographie de ce groupe en Amérique du Nord est intrigante à cause des disjonctions dans sa distribution et la possibilité que Rhodiola rhodantha (A.Gray) H.Jacobsen (2n = 7 II ) et Rhodiola rosea L. (2n = 11 II ) se soient hybridées pour former Rhodiola integrifolia Raf. (2n = 18 II ). Des études récentes réalisées sur Rhodiola d'Amérique du Nord suggèrent que la taxonomie actuelle de ce groupe est erronée. Les auteurs ont analysé les séquences d'ADN nucléaire et chloroplastique (espaceur transcrit interne (ETI), intron trnL, espaceur trnL-trnF, et espaceur trnS-trnG) du taxon des Rhodiola d'Amérique du Nord. Ils ont combiné leur données avec les séquences des espèces de Rhodiola d'Asie tirées de GenBank, réalisé des analyses phylogé-nétiques de parcimonie, par maximum de vraisemblance et bayésienne, et appliqué un modèle d'horloge moléculaire bayési-enne aux données de l'ETI. Leurs analyses révèlent l'existence de deux clades principaux de Rhodiola, suggèrent que l'hybridation entre les lignages R. rhodantha et R. rosea était possible, montrent l'existence de deux clades distincts à l'intérieur de R. integrifolia et démontrent qu'une population de Rhodiola de Black Hills, Dakota du Nord, devrait être re-classifiée en tant qu'orpin de Leedy. Ils recommandent que R. integrifolia soit révisé...

Invasive Species Removal Promotes Habitat Restoration but Does Not Immediately Improve the Condition of a Threatened Plant Subspecies

“…Some evidence also suggests that our finding from SEMs of etiolated Leedy's roseroot stems in lower light and temperature could indicate stress. Olfelt and Freyman (2014) proposed that Leedy's roseroot may have occurred along glacial margins during the Pleistocene. Glacial margins would represent open, high-light, lowcompetition environments (Horsák et al 2015), suggesting that Leedy's roseroot would be intolerant of low light.…”

“…Several characteristics of Leedy's roseroot suggested that it might respond positively to removal of Japanese knotweed shade. Olfelt and Freyman (2014) proposed that Leedy's roseroot occurred adjacent to glacial margins during the Pleistocene. Such periglacial relicts may be characterized by open, high-light habitats and low-competition conditions (Horsák et al 2015).…”

Genetic Diversity in Natural Populations of Rhodiola Species of Different Adaptation Strategies

“…There is great interest worldwide in the pharmacological compounds of the various Rhodiola species [ 1 , 2 ], the extracts of which have been used for centuries in traditional European and Chinese medicine to increase stamina, reduce the effects of ageing, and treat a variety of diseases [ 3 , 4 , 5 , 6 ]. With the implementation of the Nagoya Protocol in 2021, the search for new domestically viable medicinal plant resources has become particularly important for each country [ 7 ].…”

Intercontinental migration pattern and genetic differentiation of arctic‐alpine Rhodiola rosea L.: A chloroplast DNA survey

“…It is a dioecious, cold‐adapted perennial, occupying a narrow range of the arctic‐alpine habitats (Figure ). In eastern North America, it is restricted to the eastern coastal areas (Cuerrier, Archambault, Rapinski, & Bruneau, ; Ohba, ; Olfelt & Freyman, ).…”