Genetic heritage of sweet chestnut genotypes in Montseny Natural Park, Catalonia

The fruits of sweet chestnut (Castanea sativa Mill.) have traditionally been an important economical income for local people who live in the Montseny area (mountain located in the northeast of Catalonia-Spain). At the beginning of the last century, the chestnuts of Montseny were highly appreciated for their high quality and mainly exported to France. However, after several decades of unmanaged chestnut groves, combined with the virulent emergency of new diseases such as canker (Cryphonectria parasitica), many of these chestnut trees have disappeared or are at risk of extinction. Therefore, the social interest to re-valuate the local and native products is currently growing, and in this area, demand is increasing to replant native cultivars of C. sativa to produce fruit. Within this context, 120 genotypes distributed around Montseny were selected for the study. Then, morphology, phenology and fruit characterization parameters were studied in all genotypes, and 11 molecular markers (SSRs) analysed. All studied parameters showed low genetic diversity of Montseny chestnut trees, indicating that inbreeding is occurring. In addition, the presence of two clonal groups widely distributed throughout the mountain were identified, suggesting that chestnut trees were probably grafted in the past mainly with one or two ancient ‘cultivars’. The present study shows the current genetic variability of the Montseny chestnut trees indicating that conservation of genetic heritage must be a priority. In addition, four chestnut genotypes have been selected for its registration as cultivars. The selected plant material will ensure to producers to plant chestnut trees with high quality sweet chestnuts well adapted to this area.