Euphytica 111: 121–125, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands. 121 Assessment of genetic relationships in Mentha species S.P.S. Khanuja, A.K. Shasany, Alka Srivastava & Sushil Kumar Genetic resources and Biotechnology Division, Central Institute of Medicinal and Aromatic Plants (CIMAP), Lucknow-226015, India Received 8 September 1998; accepted 18 June 1999 Key words: DNA fingerprinting, Mentha, phylogenetic tree, RAPD Summary 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 × 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 × 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. Introduction The industrial mint crops are cultivated in several countries for their essential oils. The oil, menthol, carvone, lemoline, dementholated oil and terpene frac- tions from the latter are variously used in the cosmet- ics, pharmaceuticals, food, confectionery and liquor industries. Genetic improvement(s) in Mentha species leading to wider adaptation, higher herbage and/or es- sential oil yield(s) and better quality of oil will permit economical production of mint related commodities. Currently, much emphasis is being laid on conser- vation of plant germplasm (varied genetic resources) as valuable bio-resource. These collections are expec- ted to serve as repositories of biodiversity for numer- ous species available as utilisable sources of desired genes in plant improvement programmes. The import- ance of molecular markers exists for not only authen- tication of the genotypes of released cultivars of medi- cinal and aromatic plants, but also in assessing and exploiting the genetic variability through molecular approaches. Developing DNA markers/fingerprints of all the genetic resources of the medicinally and indus- trially important plants, is a necessity for generating a molecular database to catalogue as well as to utilise the information in a systematic way. Mentha spe- cies, which represent a substantial variability in origin as well as chemotype properties for the oil and its components, do need to be documented well for estab- lishing phylogenetic relationships and unique marker profiles at DNA level. These molecular relationship and markers can be useful for designing strategies for gene introgression and breeding programmes to pro- duce desired recombinant hybrid genotypes with both oil quality and yield. Such unique DNA fingerprints will also be useful in protecting the rights of contrib- uting research institutes and laboratories with present day status of IPR. The DNA fingerprinting technique of Randomly Amplified Polymorphic DNA (RAPD) provides an un-