Abstract
Coptosperma graveolens subsp. arabicum (Rubiaceae) is a shrub or small tree and currently endangered in Saudi Arabia. In this study, ribulose-1, 5-biphosphate carboxylase (rbcL) gene sequence and random amplification of polymorphic DNA (RAPD) profile of C. graveolens were determined. Our study showed that this species is phylogenetically related with Tarenna supra axilaris, Coptosperma sp. and Paracephaelis sp. group on the basis of rbcL gene sequences. The studied specimen and related taxa inferred from partial rbcL gene sequence demonstrated a distinct lineage; therefore, could distinguish the species as C. graveolens unequivocally. The specimen (6R1) demonstrated the highest level of sequence similarities (99.5%) with three close species in the group. RAPD profile of C. graveolens generated amplified products ranging from 218 to 1338 bp. A total of 18 bands were observed for plant species using 5 commercially available RAPD primers (P). The number of major bands for the plant species for a single primer ranged from 3 to 5. The maximum number of major bands was observed for the P1 (5 bands), 4 bands for P4 and the equal number of bands (3) for P2, P3 and P5. The determined rbcL gene sequence and RAPD profile of the endangered plant species C. graveolens will improve the identification process with morphology based taxonomic methods.