Propagation of Tropical Plants by Tissue Culture

Experiments were conducted to establish more efficient propagation systems for aroids and other monocot families by tissue culture. Scindapsis aureus (Lind, and Andre.) Engl was chosen as a model plant. Top 1st and 2nd nodes produced multiple shoots in Murashige-Skoog medium supplemented with 10 ppm BA which elongated when transferred to 1 ppm BA, and formed roots in 1 ppm NAA medium; the resulting plantlets were successfully cultured in pots. Internodal and leaf tissues also produced adventitious buds in medium supplemented with BA + NAA. From the results of antiauxin treatment, involvement of endogenous auxin in bud formation was suggested. Intercalary meristem in node tissue and marginal meristem in leaf tissue were suggested as sites of auxin production. A hypothesis of basipetal movement and accumulation of endogenous auxin was proposed to explain the location of bud formation in leaf segment culture in BA medium. Polyploidy was not found in the plantlets obtained by node culture. Propagation by node culture was successful in Philodendron oxycardium Schott, Philodendron lacerum (Jacq.) Schott, Spathiphyllum 'Clevelandii', and Alocasia cucullata (Lour.) Schott. From these results, a general procedure for propagation of aroids was proposed. Similar procedure can be applied to other plants in different families (Liliaceae, Asparagus myriocladus Hort, Zingiberaceae, Zingiber officinale Roscoe, and Orchidaceae, Doritaenopsis Dorette. However, Asparagus myriocladus failed to form roots. Neomarica caerulea (Ker-Gaw) Sprague in Iridales, which is phylogenetically located between Orchidales and Liliales, formed multiple shoots by node culture. Woody monocots and dicots were not successfully propagated by this method. Anatomical study on node culture suggests that several epidermal cells and cells of some subepidermal layers are involved in forming a bud. Histochemical and microautoradiographic studies showed increases in DNA, RNA, proteins, reducing sugars, activities of respiration enzymes, and activity of peroxidase prior to bud formation. Anatomical study of leaf culture suggested that several cell layers were involved in forming a tumor-like tissue. Adventitious buds formed on the peripheral zone in the tumor