In vitro propagation and ex situ conservation of Limonium etruscum, a coastal endemic species from Tuscany

Limonium etruscum (Arrigoni and Rizzotto, fam. Plumbaginaceae) is a coastal point-like endemism, localized in the Parco Regionale della Maremma (Grosseto, Italy) and in a relictual area near Livorno (Italy). It mainly lives in retrodunal depressions, on salty sandy soil. This species is a perennial herb with a basal rosette, flowering from June to August. The species is arranged in five populations constituted by several individuals and all populations are subject to fluctuation in the numbers of individuals. According to these data, L. etruscum is classified as endangered (EN) following the IUCN criteria, threatened mainly by habitat loss, for which the conservation projects are important. With the aim of ex-situ conservation of this species, it was developed a preliminary protocol for in-vitro propagation, starting from immature flower stalks and growing on agarized MS substrate with the addition of different growth-regulators in different doses. The best performing protocol included BAP (0.5 g L^-1) for the proliferation phase and IBA (1 mg L^-1) for the rooting phase. Since the plant lives in saline soils, the rooting phase was optimized trying to reduce the available water content, testing a higher dose of agar (10 g L^-1), mannitol (20 g L^-1) and NaCl (1 g L^-1). The latter was the most successful, producing more robust plantlets. A hundred of these specimens were acclimatized and they all bloomed in the subsequent summer. This work opens interesting perspectives in order to obtain a wider in-vitro and in-vivo collection, useful for ex-situ conservation of this species and future reintroduction programs if necessary.