Phylogenetic Relationships of Muehlenbeckia, Fallopia, and Reynoutria (Polygonaceae) Investigated with Chloroplast and Nuclear Sequence Data

The monophyly of Muehlenbeckia and evolutionary relationships with other genera in Polygonoideae have been unclear. The traditional placement of Muehlenbeckia in Coccolobeae (Eriogonoideae) along with Antigonon, Brunnichia, and Coccoloba has not been supported in previous studies, and it is more closely related to Fallopia in Polygonoideae. Molecular data from 22 species of Muehlenbeckia and from representatives of Atraphaxis, Fallopia (including Reynoutria), Polygonella, and Polygonum s.s. were generated from five chloroplast regions (matK, ndhF, 3′rps16-5′trnK, trnL-trnF 3′trnV-ndhC) and two nuclear gene regions (second intron of LEAFY, internal transcribed spacer). Analyses used maximum likelihood and maximum parsimony methods. Neither Fallopia or Muehlenbeckia is monophyletic, with most species of Muehlenbeckia related to Fallopia. Four clades are named as a result of this study: Duma, Fallopia, Muehlenbeckia, and Reynoutria. Duma contains three Australian species of Muehlenbeckia that form a clade sister to the clade containing Polygonum and Polygonella. Relationships within Muehlenbeckia correspond to geographic distribution patterns, and relationships in the Reynoutria and Fallopia clades correlate with base chromosome numbers.