Generic delimitation of the genera Fragaria and Duchesnea inferred from chloroplast DNA sequence data

Background and Aim: Fragaria and Duchesnea are two representative the tribe Potentilleae subfamily Rosoidea and family Rosaceae. The first genus comprises three species (including Fragaria viridis, F. vesca, and F. × ananassa), while Duchesnea indica is the only representative of the second genus in the Flora of Iran. They resembling to each other in terms of their creeping stoloniferous stem, trifoliate leaves. However, Duchesnea indica is identified by its inedible dry fruits, called as Indian strawberry or false strawberry. Fragaria and Duchesnea share a common classification history and their taxonomic delimitation is influenced by several controversies. Newer molecular approaches are essential for resolving these problems.Methods: In the current study generic delimitation of Fragaria and Duchesnea were investigated using psbA-trnH region of chloroplast DNA. A total of ۶ species from the two genera, plus ۱۰ previously sequenced data from GenBank, were analyzed for psbA-trnH intergenic spacer region. Filipendulla vulgaris and Rosa rugosa selected as outgroups species. Total DNA was extracted from freshly collected specimen using modified CTAB procedure. The sequencing results were used to construct a phylogenetic tree using the maximum parsimony (MP) criterion as implemented in PAUP. The heuristic searches, ۱۰۰ replications of random addition sequence, Tree-bisection-reconnection (TBR) branch swapping, with MulTrees on and steepest descent off was carried out. The bootstrap values were calculated from ۲۰,۰۰۰ replicates, simple sequence addition, and TBR branch swapping with ‘Maxtrees’ limit of ۱۰۰ trees per bootstrap replicate.Results: Strict consensus tree of most parsimonious tree resulting from phylogenetic analysis showed monophyly of Fragaria and Duchesnea. The representative of Duchesnea nested within the clade containing Potentilla species and confirmed Potentilla reptans as a closest relative of D. indica. Nevertheless, interspecific relationships within Fragaria remained unresolved. Conclusion: Furthermore, the current findings support previous molecular analyzes and indicate the presence of the two genera in the common tribe Potentilleae, but in two distinct subfamilies Fragariinae and Potentillinae.

Keywords:

Fragaria , Duchesnea , phylogeny , cpDNA , psbA-trnH