Shoot organogenesis and plant regeneration in Begonia coptidifolia

An efficient regeneration protocol was established for a rare plant species, Begonia coptidifolia. Using leaf explants, adventitious shoots were induced on Murashige and Skoog (MS) basal medium using various concentrations (1.0-10.0 mM) of three cytokinins, 6-benzyladenine (BA), thidiazuron (TDZ) and kinetin (KIN). However, adventitious shoots could not be induced on MS medium supplemented with auxins [α-naphthaleneacetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-D)] tested in the 1.0-10.0 mM range. The highest number of shoots per explant (31.2) was induced on MS medium with 5.0 mM BA and 1.0 mM NAA. Although roots were induced in ½MS medium free of plant growth regulators, the time to form roots was shorter in the 0.5 mM IBA, 0.5 mM IAA and 0.5 mM NAA treatments. Following acclimatization, over 95% of plantlets survived in a substrate of sand and humus (1:1, v/v). Over 200 plantlets were reintroduced to their natural habit, and over 50% of plants survived after one year.