Assessment of intraspecific variation in half-sibs of Quercus petraea (Matt.) Liebl. ‘plus’ trees

Quercus petraea (Matt.) Liebl. (sessile oak) is a long-lived, widespread species with forest rotation cycles that are considerably longer than many other species in European forestry. Together with other oak species they are of high economic and ecological importance. In Flanders (Belgium), apart from the creation of suitable situations for natural regeneration, native species (including sessile oak) are being actively introduced to enhance the authenticity of particular sites. To take into account the existing genetic diversity in such practices, there was a need to determine the available genetic variation in the selected ‘plus’ trees from which the progeny will be used in the (re)introduction programmes. We analysed the half-sibs of nine different ‘plus’ trees from officially approved stands, that were selected because of their extraordinary phenotype. RAPD and AFLP techniques were used to assess the level of genetic variation. AFLP was only used for the analysis of the progeny from two different ‘plus’ trees. A screening with eight selected decanucleotide primers (for RAPD) and six primer combinations (for AFLP) allowed a presence/absence matrix to be constructed for the estimation of similarity for each pair of individuals. This similarity matrix was the basis for cluster and principal co-ordinate analysis and the calculation of population genetic parameters (for the RAPD data). These analyses showed that the pool of investigated progenies comprised a considerable amount of genetic variation, which makes them suitable for the above-mentioned introduction initiatives.