Evaluation Of Six Candidate DNA Barcoding Loci In Ficus (Moraceae) Of China

Genus Ficus (Moraceae), with about750species, diverse habits and complicated co-evolutionary history with fig-wasps, is a notoriously difficult group in taxonomy. DNA barcoding is expected to bring light to the identification of Ficus but need evaluation of candidate loci. Based on five plastid loci (rbcL, matK, trnH-psbA, psbK-psbI, atpF-atpH) and a nuclear locus (ITS), we calculated their genetic distances and DNA barcoding gaps individually and in combination, and constructed phylogenetic trees to test their ability to distinguish the species of the genus.228samples representing63putative species in Ficus of China were included in this study. The results demonstrated that ITS has the most variable sites, greater intra-and inter-specific divergences, the highest species discrimination rate (72%) and higher primer universality among the single loci. It is followed by psbK-psbI and trnH-psbA with moderate variation and considerably lower species discrimination rates (about19%), whereas matK, rbcL and atpF-atpH couldn't effectively separate the species. Among the possible combinations of loci, ITS+trnH-psbA performed best but only marginally improved species resolution over ITS alone (75%vs72%). Therefore, we recommend using ITS as a single DNA barcoding locus in Ficus.