Micropropagation of Corema album from adult plants in semisolid medium and temporary immersion bioreactor

Corema album is one of the two species of flowering plants in the Corema genus, from family Ericaceae, and is also known for its common name Camarinha or Portuguese crowberry. It has a restricted distribution, being confined to the western Atlantic coast of the Iberian Peninsula and Aquitaine in France, in dune systems or in low pine forests. The shrub is exploited because of its food, ornamental and medicinal value and the regeneration rate in the natural habitat is very low. For the first time, an in vitro propagation protocol has been developed from nodal segments obtained from adult plants in the field. Several nutrient formulations were tested for the establishment and the best results, in terms of highest bud break frequency (6.7%), were achieved with the woody plant medium (WPM) basal salts, supplemented with 2.0 mg l −1 2iP at pH 5.6. WPM was then used for sub-culturing of shoots every 8 weeks and to perform an assay to test the effect of different cytokinins (BA, Kin 2iP and m T) combinations in the multiplication phase. Of all the combinations tested, 2.0 mg l −1 2iP with 1.0 mg l −1 Kin is the most beneficial with 100% bud break, 6.8 new shoots, with 14.2 mm average length and the shoots regenerated were healthy. A study with a temporary immersion bioreactor (SETIS™) was performed, with promises results, where more than double the multiplication rate was achieved compared with the previous semisolid medium. However, in this system, vitrification processes have occurred which may compromise the viability of the shoots. Rooting, which proved to be a difficult process, was best induced ex vitro by dipping of the microshoots in a 2.0 g l −1 IBA solution for 10 s, followed by placement in jiffy-7C pellets, with 20% of rooting and an average of 5.3 roots and 43.8 mm long. The microplants were potted and acclimatized, showed 100% survival. Key message Corema album , exploited because of its food, ornamental and medicinal value, has a restricted distribution and a very low regeneration rate in the natural habitat. For the first time, an in vitro regeneration protocol has been developed from nodal segments obtained from adult plants in the field which is promising for a future programme of breeding and valorisation of this species.