Characterization of genetic diversity in poplar stands and evaluation of potential breeding between natural and cultivated populations in Mediterranean environment

The objectives of this work were the characterization of the spatial genetic diversity in poplar populations at the stand level, and the study of the potential breeding between natural and cultivated populations in Mediterranean environment. To this end, two test areas were selected in the Migliarino-San Rossore-Massaciuccoli Regional Park in Tuscany (Italy): A) a mixed forest stand; B) a scattered Populus population in the wetland area of "lake of Massaciuccoli". Test area A is a naturally-originated mixed forest stand near to poplar plantations. In the forest, the prevailing tree species are Populus alba and P. x canescens. In the test area B, single and clustered trees of Populus spp. are scattered along the lake, and close to poplar plantations. In the test area A an experimental plot 2500 m2 large has been designed inside the forest. All Populus trees within the two test area have been identified and their position have been collected by GPS. The analysis of spatial and genetic structure of the two poplar stands was performed using Geneland. Nuclear microsatellites were used to evaluate genetic diversity of poplar populations and level of breeding between natural and cultivated Populus. The results of Geneland clearly showed that four distinct clusters can be identified in the area A, indicating the presence of gene flow barriers. The same analysis indicates two clusters in area B with a gene flow between clusters higher than in area A. In test area A, we found hybridization between the poplar stand and the Populus plantation. Therefore, the possible cultivation of transgenic poplar close to naturally originated stands might influence their biodiversity. The study has been performed within the framework of the European project LIFE08 NAT/IT/342.