Propagation and reintroduction to its habitat of Metabriggsia ovalifolia W. T. Wang

An efficient protocol providing a dual regeneration pathway via shoot organogenesis and somatic embryogenesis for an endangered species, Metabriggsia ovalifolia W. T. Wang, was established from leaf explants. When applied at 2.5 M, the cytokinins 6-benzyladenine or thidiazuron and the auxins indole-3-butyric acid, α-naphthaleneacetic acid and indole-3-acetic acid could induce shoots when on basal Murashige and Skoog medium. BA and TDZ at 5-10 M could induce both shoots and somatic embryos. A higher concentration (25 M) of TDZ induced only somatic embryos. The same concentration of BA induced both adventitious shoots and somatic embryos. Somatic embryos germinated easily when left on the same media, but formed adventitious roots in two weeks on MS supplemented with 0.5 M NAA, 0.5 M IBA and 0.1% activated charcoal. Over 90% of plantlets survived following acclimatization and transfer to a mixture of sand and vermiculite (1: 1, v/v) in trays. In the following another test, Leaf and petiole segments derived from 1-year-old transplanted potted plants originally derived from in vitro culture were used to study the effects of plant growth regulators and orientation on the induction of adventitious shoots and roots. Leaf cuttings and petiole segments dipped in 20.0 µM 6-benzyladenine for 30 min induced the highest number of shoots per explant among the PGRs tested and 1 - 20 µM indole-3-butyric acid induced more roots than indole-3-acetic acid or α-naphthaleneacetic acid. Leaf cuttings placed abaxial side down induced significantly more adventitious shoots than leaf cuttings placed abaxial side up. More than 95% of plantlets survived when transferred to square plastic trays