Further insights into the phylogeny of Arabidopsis (Brassicaceae) from nuclear Atmyb2 flanking sequence.

Arabidopsis thaliana is the preeminent plant model organism. However, significant advances in evolution and ecology are being made by expanding the scope of research beyond this single species into the broader genus Arabidopsis. Surprisingly, few studies have rigorously investigated phylogenetic relationships between the nine Arabidopsis species, and this study evaluates both these and hypotheses related to two instances of intra-generic hybridization. DNA sequences from the 5' flanking region of the nuclear Atmyb2 gene from 12 of the 14 Arabidopsis taxa were used to reconstruct the generic phylogeny. The strict consensus tree was highly concordant with previous studies, identifying lineages corresponding to widespread species but exhibiting a large basal polytomy. Our data indicates that the paternal parent of the allopolyploid A. suecica is A. neglecta rather than A. arenosa s.l., although the need for a detailed phylogeographical study of these three species is noted. Finally, our data provided additional phylogenetic evidence of hybridization between Arabidopsis lyrata s.l. and A. halleri s.l. Taken together, the well-defined lineages within the genus and the potential for hybridization between them highlight Arabidopsis as a promising group for comparative and experimental studies of hybridization.