Regioni di Provenienza per il frassino maggiore

Identification of Regions of Provenance in common ash The identification of Regions of Provenance is a basic aspect for a rational management of activities linked with forest trees propagation, including afforestation and in situ genetic preservation. The purpose of this study was the evaluation of neutral DNA markers (microsatellites) as a tool to study genetic variability distribution of common ash in northern Italy, and to group populations according to their genetic similarity. 31 natural ash populations were sampled and DNA was extracted. Six microsatellite primer pairs were used to detect genetic variability. Additionally, the ecological chracteristics of the collection sites were analysed and homogeneous regions were defined. Common ash populations from Northern Italy proved to have a large genetic variability and all the examined populations showed a consistent excess of homozygotes. Distribution of genetic variability is only partially related with geographical distances between populations; moreover genetic differentiation among populations is quite low, probably due to the lack of barrier to gene flow. The soil seems not to influence the distribution of genetic variability, while the climatic conditions appear to have a major effect. Despite the low genetic differentiation it has been possible to identify six Regions of Provenance (namely Alps with crystalline soil, Po Valley, Alps with calcareous soil, Hilly regions of Piedmont, Apennines and Ligurian mountains), sufficiently homogeneous both for ecological and genetic conditions.