Mentors: Franz Hoffmann, Shyun-Shyun Hoffmann-Tsay
The purpose of this study was to define the optimum conditions for the micropropagation of Strelitzia reginae through the culture of dissected embryosand multiple shoot formation (organogenesis). Strelitzia reginae is an important monocotyledonous ornamental plant native to South Africa. However, its success is limited by slow growth, the absence of pure-bred varieties and poor seed-production outside of South Africa. Micropropagation as an alternative propagation and cloning method would greatly contribute to overcoming the limitations this species poses to the horticultural industry and landscaping in warmer regions worldwide. Despite the commercial importance, a method for micropropagation has not been established yet due to the recalcitrance of the species. Strelitzia reginae seeds, harvested at different maturity, were cultured on ½ MS agar-solidified medium with different supplements. The addition of 0.2 mg/L of the growth regulator thidiazuron (TDZ) and 30 g/L sucrose turned out to be most successful. The study showed that the optimum embryo stage for culture is when the seeds have a dark yellow to orange aril with a golden to brown colored seed coat and a friable to solid endosperm texture. The ideal size of the embryo was found to be from 6.9–7.4 mm. Cultured embryos excreted a bluish-black pigment that has not been described in the literature. The pigment diffused into the medium and formed a skin-like layer that covered the explant. Despite the excretion, the embryos started to germinate, produced callus and, within three months, multiple shoots formed. The shoots are now being transferred to rooting medium before they can be explanted into soil.