Taxonomic reaffirmation of some members of family cannabaceae, moraceae, rhamnaceae, rosaceae and urticaceae of order rosales using DNA barcoding markers

DNA Barcode Analysis was carried out as new taxonomic approach to re-affirm the identity and the phylogenetic relationship of five families of order Rosales by using three molecular markers such as rbcL, matK and trnH-psbA. This study will serve as contribution to the previous taxonomic position of the order Rosales on the basis of morphological characters as well as DNA sequence data. According to the DNA Barcode data cladogram of order Rosales indicated that family Moraceae formed an individual clade in all Neighbour Joining trees formed on the basis of rbcL, matK, trnH-psbA, rbcL+matK and rbcL+matK+trnH-psbA while in previous studies it was sister to Urticaceae and Cannabaceae. Another change was also observed in the placement of Family Rosaceae that did not form a separate clade as it did in previous studies but it was sister to Cannabaceae, Rhamnaceae and Urticaceae and embedded among these families. Our study does not support the previous taxonomic position of order Rosales based on morphological characters and some DNA sequences which are not standard barcodes now. The PCR amplification success rate was found highest 96% for rbcL followed by matK 64% while lowest for trnH-psbA 58%. The gene sequencing tree was successfully constructed when markers were used both singly and in combinations. The phylogenetic tree analysis demonstrated that, separate clusters forming species with more than 50% bootstrap value were the discriminate species, indicating high reliability of evolutionary relationship among the taxa. In the present study it was found that all three DNA Barcode markers when employed in combination exhibited maximum discriminatory power amongst all the studied species in the families of order Rosales. (author)