ALLOZYME, CHLOROPLAST DNA AND RAPD MARKERS FOR DETERMINING GENETIC-RELATIONSHIPS BETWEEN ABIES-ALBA AND THE RELIC POPULATION OF ABIES NEBRODENSIS

Allozyme, chloroplast (cpDNA) and random amplified polymorphic DNA (RA PD) markers have been used to estimate genetic and taxonomic relations hips among different populations of Abies alba and the relic populatio n of A. nebrodensis. Twelve isozyme gene loci, as well as restriction fragment length polymorphism (RFLP) at cpDNA spacer regions between t- RNA genes were analysed. Moreover, a set of 60 random sequence 10-mer primers were tested. Over all isozyme loci, evident differences in all ele frequencies among A. nebrodensis and A. alba populations were foun d, particularly at 2 loci, phosphoglucose isomerase (Pgi-a) and shikim ate dehydrogenase) (Skd-a). More than 10% of the total genetic diversi ty was due to differences among populations. High values of genetic di stances among populations were also found. Out of the 60 primers teste d, 12 resulted in a polymorphic banding pattern both within and among populations. A total of 84 RAPD fragments were produced by the 12 sele cted primers. A phenogram of relationships among populations was const ructed based on RAPD band sharing: the differentiation of the A. nebro densis population was evident. The analysis of molecular variance (AMO VA) was used to apportion the variation among individuals within popul ations and among populations. There was considerable variation within each population: even so, genetic divergence was found among populatio ns. This pattern of genetic variation was very different from that rep orted for inbred species. Identical cpDNA amplification and restrictio n patterns were observed among all the individuals sampled from the po pulations. Taken together, the results of allozyme and RAPDs show a cl ear differentiation among A. nebrodensis and A. alba populations and p rovide support for their classification into two different taxonomic g roups.