The low copy nuclear region, RPB2 as a novel DNA barcode region for species identification in the rattan genus (Arecaceae).

Taxonomic complexities, like environmental plasticity and homoplasy, make precise identification challenging in , the genus of spiny climbing palms of the subfamily Calamoideae (Arecaceae). In the present study, the species discriminatory power of twelve potential DNA barcode regions (L, K, A-H, CBK-IF-H, Z-M, ITS1, ITS2, PRK, and RPB2) were evaluated in 21 species of from the Western Ghats region of India, using distance, tree, and similarity based statistical methods. Except for the low copy nuclear region, RPB2, none of the tested plastid loci or nuclear loci ITS, either singly or in combinations, could discriminate all the species of due to low substitution rate of plastid regions and multiple copies of ITS respectively. The RPB2 locus showed highest species resolution with 96% accuracy in similarity based analysis, indicating its potential and efficiency as a barcode locus for the genus. The putative " complex" based on overlapping morphology was successfully resolved as six distinct, though closely related, species. The analysis also indicates that is a morphological variant of In spite of being a low copy nuclear gene region, RPB2 provided an efficient barcode to delineate species and has the potential to further extend its use as a prospective barcode to other Palm genera.