Propagation of Calendula maritima Guss. (Asteraceae) through Biotechnological Techniques for Possible Usage in Phytotherapy

The genus Calendula (Asteraceae) includes several species that are renowned for their therapeutic properties and/or use as ingredients in the preparation of cosmetics. The rare and critically endangered sea marigold, Calendula maritima Guss., an endemic species from Western Sicily, has also been recognized as a potential "farm plant species" for several important compounds used in cosmetics. However, the few remnant populations of this species are currently threatened with extinction because of several factors, such as hybridization with the congeneric species Calendula suffruticosa subsp. fulgida (Raf.) Guadagno and anthropogenic disturbance of its habitat. Therefore, in order to preserve the genetic integrity from pure genetic lineages, seed-based propagation and seed storage are not recommended for either conservation or massive production purposes. In this paper, we describe a protocol adopted for mass propagation of C. maritima from selected genotypes. Nodal segments collected from selected plants growing in the field were used as starting explants and were cultured for micropropagation on MS medium with and without phloroglucinol. New shoots produced were cultured for rooting under several conditions with the aim of finding the best procedure favoring root induction. The best rooting performance was obtained with zeolite and rooted plants were successfully acclimatized outdoors. The technique described allowed the multiplication of genotypes of interest as well as to overcome the problems of hybridization of this species, hence contributing concretely to the conservation of the sea marigold.