Multiple shoot induction and plant regeneration of the endangered species Crepis novoana

In vitro culture is a useful tool in the ex situ conservation of rare, endemic, and threatened plant species. Crepis novoana (Compositae) is an endangered endemic in northwestern Spain. Use of in vitro culture tools is necessary due to the poor conservation status of populations of the species. The systems of in vitro propagation developed for this species in the present study were caulogenesis from leaf explants and growth of axillary buds from shoots. Explants were produced by placing fragments of leaves on Murashige and Skoog medium (MS) supplemented with 2.22 mu M 6-benzyladenine (BA) and 2.69 mu M naphthaleneacetic acid (NAA); caulogenesis was induced in 80% of explants, with development of a mean number of 2.48 shoots per explant. Axillary bud development from shoots was highest with MS supplemented with 4.44 mu M BA and 0.54 mu M NAA, resulting in production of a mean number of 49.77 shoots per explant. Immersion of the basal side of shoots in a solution of 5.37 mM NAA for 30 s yielded 90% success in the production of rooted shoots. Plantlets were well acclimatized, and almost 100% of plants transferred to soil recovered successfully.