The Sardinian Germplasm Bank (BG-SAR): an important tool for the preservation of Mediterranean plant diversity. Conservation studies on Mediterranean threatened flora and vegetation

The Sardinian Germplasm Bank (BG-SAR) is part of the Hortus Botanicus Karalitanus (HBK), which belongs to the University of Cagliari (Italy). The main objective of BG-SAR is the conservation, study and management of germplasm of Sardinian endemic, threatened and policy species (taxa inserted in the Habitat Directive 92/43/EEC, CITES and Bern Convention; Fenu et al., 2015), as well as Crop Wild Relatives (CWR), landraces and useful plants. Before of long-term conservation at -25°C, the image digitalization of each seed lot is acquired, in order to allow subsequent studies through the innovative morphocolorimetric techniques. Studies on the germination ecophysiology are carried out to increase the ecological knowledge and define the optimum germination protocol for all the preserved taxa. In the last years, particular attention was given to studies on thermal time, niche modeling and the effect of global warming on the seed germination of mountain Mediterranean species (e.g. Porceddu et al., 2013), and to understand how the thermal thresholds for dormancy loss and germination may vary along an altitudinal gradient. Moreover, comparative studies on the effects of abiotic stresses, such as salinity (e.g. NaCl), or the nutrient availability (e.g. KNO3) were carried out among several Mediterranean species, especially for endangered coastal taxa (e.g. Santo et al., 2014). In the case of invasive alien species (IAS), the identification of their tolerance to salt, has helped us to predict their potential invasive power also in salt habitats. In addition, archaeological materials such as seeds and fruits were studied and stored at BG-SAR, with the aim of investigating the evolution of crops and wild plants. All these approaches allow to BG-SAR, not only to attain an effective ex-situ conservation, but also to face actual and important problems, such as global warming and invasiveness of alien species and, deepen the knowledge of the endangered Mediterranean species.