INSTYTUT DENDROLOGII

Genetic variability of Scots pine (Pinus sylvestris L.) and its progenies

Protection and preservation of genetic resources are among strategic aims of silviculture and selection of forests. The programme which is currently carried out by the General Directorate of the State Forests focuses on the preservation of genetic diversity of local and indigenous populations of trees. ln order to meet this aim, excluded seed stands are selected accordingly with their phenotypical features, and registered progeny plantations by artificial regeneration are established, which protects genetic resources. So far no adequate genetic research has been done to verify the aforementioned method. In recent years the first attempt to genetically verify the assumptions of phenotypical selection of Scots pine (Pinus sylvestris L.) has been made in the lnstitute of Dendrology of the Polish Academy of Sciences. The aim of the research was to study the genetic variation of maternal populations (selected seed stands) and progeny populations (artificial and natural regeneration). The research was conducted on two groups of populations by use of allozymes as genetic markers. The first group enabled to compare genetic variation of the maternal stand and its progeny in the form of artificial regeneration. The other group consisted of a group of populations which included maternal stands and their progeny populations in the form of natural regeneration and two artificial regenerations established in different years. A multi-directional comparative analysis of genetic variation was carried out in this group.

Thirteen enzyme systems controlled by 25 allozyme loci were analyzed using starch gel electrophoresis. On the basis of the estimated allele frequencies, the following parameters of genetic variability were computed: average N_A and effective N_E number of alleles per locus, percentage of polymorphic loci P (99% criterion), expected H_E and observed H_O heterozygosity, fixation index F. Genetic differences between populations were measured by F_ST and the genetic distance index D_N. To better visualize genetic relationships between populations, matrices of D_N values were clustered using the unweighted pair group method (UPGMA).

The research has demonstrated that all the analysed populations of Scots pine, including maternal stands and their progeny populations, show high level of genetic variation, which does not differ from the results quoted for this species in the literature.

The maintenance of a similar level of genetic variation for all the progeny populations of seed stands, of both natural and artificial regenerations, (progeny plantations of various seed years) has been observed. Moreover, all the progeny populations maintain the level of genetic variation similar to their maternal populations (excluded seed stands). lt should, however, be considered that the preservation of gene pools of progeny populations are not completely identical with gene pools of relevant maternal populations.

The results obtained from the study may be practically applied by the General Directorate of the State Forests to verify the assumptions of phenotypical selection.