Assessment of genetic relationships in Mentha species

A set of 60 random primers was used to analyse 11 accessions from six taxa of Mentha developed by CIMAP. These accessions were maintained in the national gene bank for medicinal and aromatic plants at CIMAP. A total of 630 bands could be detected as amplified products upon PCR amplification, out of which 589 were polymorphic (93.5%). Further analysis of these RAPD profiles for band similarity indices clearly differentiated five of the Mentha arvensis L. accessions from the rest. Among two accessions of Mentha spicata L. CIMAP/C33 could be distinguished from CIMAP/C32. Mentha x gracilis Sole cv. cardiaca showed a much higher similarity with Mentha spicata L. as well as Mentha arvensis L. which amongst themselves showed rather a greater distance indicating that Mentha x gracilis Sole cv. cardiaca might have evolved as a natural hybrid between M arvensis L. and M. spicata L.. In terms of uniqueness of amplified bands for developing RAPD markers, it was observed that at taxa level 298 bands were unique to one of the six taxa, singly amounting to 47.3% of total amplified fragments. Primers MAP 10 and 17 produced polymorphism only in case of M. spicata L. and Mentha spicata L. cv. viridis while MAP 08 produced polymorphic bands in all 4 other species than these two. Similarly unique patterns were observed differentiating all six species and could be used as RAPD markers for differentiating Mentha species.