DETECTION OF GENETIC DIVERSITY USING RAPD MARKERS IN THE GENUS MELALEUCA

Abstract

The genus Melaleuca belongs to the large Australian plant family Myrtaceae. In Australia there are about 200 Melaleuca species which are predominantly temperate to subtropical, although a small number of tropical species do occur. Several species of Melaleuca are harvested commercially for their essential oils, including M alternifolia for terpinen-4-ol in New South Wales, and M quinquenervia and M cajuputi in New Caledonia and Indonesia for nerolidol and 1,8-cineole respectively. Leaf material was collected from over 250 trees representing 12 Melaleuca species, from temperate, subtropical and tropical regions. Twenty sites were sampled for M alternifolia, nine sites for M. linariifolia and one to three sites for all other species. Leaf tissue was collected from two to ten trees per site and sites ranged from the Northern Territory to New South Wales. DNA was extracted from the leaf samples using a modified CTAB method and 26 RAPD primers were used to evaluate genetic variability within and between species. Both species specific and non-specific markers were identified in the 216 reproducible DNA bands scored. Genetic distances between and within species were calculated using simple matching coefficients. Cluster analysis was carried out using the UPGMA algorithm. The analysis with RAPD markers revealed a low level of diversity within the M alternifolia species compared to a number of other Melaleuca species. M. alternifolia has a limited geographic range when compared to the other species studied and this was reflected in the low level of diversity within this species.