Study on isozyme variation in Pinus pinea L.: Evidence for low polymorphism

The genetic diversity of Pinus pinea was studied by using isozymes. Seed tissues (megagametophytes and embryos) were analyzed by means of horizontal starch gel electrophoresis. A total of 37 enzyme systems were assayed from 10 populations of Pinus pinea from the northern Mediterranean. 27 enzyme systems were sufficiently revealed. They were coded by a minimum of 29 putative monomorphic loci and only 2 variable loci: menadione reductase (MNR-2) and malic enzyme (ME). Differentiation among 17 populations distributed around the Mediterranean basin was analyzed using only the ME allele frequencies due to the complex genetic control and poor quality zymograms found for MNR. Allele frequencies and genetic diversity parameters were highly variable between populations. Within population variation was less significant than between population variation. No relationship was found between the classification of the different populations according to allele frequencies of ME and the current geographic range of Pinus pinea.