The effects of benzyladenine (BAP), kinetin (KIN), zeatin (ZEA), isopentenyladenine (2iP), and thidiazuron (TDZ) were studied on in vitro growth of rudimentary embryos of Ilex paraguariensis St. Hil. Heart stage zygotic embryos were removed from seeds of immature, light green fruits and cultured aseptically on quarter-strength Murashige and Skoog medium containing 3% sucrose, 0.65% agar, and supplemented with or without three concentrations of BAP, KIN, ZEA, 2iP, or TDZ. Cultures were incubated in darkness at 27 ± 2°C. Media containing 4.4 × 10 −6 M BAP, 4.6 × 10 −6 M KIN, or 4.9 × 10 −6 M 2iP were totally ineffective in inducing embryo growth after culture for 28 days. However, lower concentrations of these compounds (4.4 × 10 −8 M BAP, 4.6 × 10 −8 M KIN, 4.5 × 10 −8 M ZEA, or 4.9 × 10 −8 M 2iP) promoted embryo growth. TDZ at 9.9 × 10 −9 M, 9.9 × 10 −8 M, or 9.9 × 10 −7 M induced embryo growth at similar rates. The maximum percentage of embryos converted to seedlings was achieved when the medium was supplemented with 4.5 × 10 −7 M ZEA.

Nodal segments as well as shoot tips and apical meristems of 2-yr-old "mat6'" plants (llex paraguariensis St. Hil.) were cultured in vitro to establish micropropagation systems. Maximum shoot regeneration was achieved when nodal segments were cultured with 1/4 Murashige and Skoog (MS) medium with 3% sucrose. We induced roots to differentiate by transferring the regenerated shoots onto the same medium, solidified with 2.5 g Phytagel per 1 and supplemented with indole-3-butyric acid (7.4 ~M) and finally transferring shoots to 1/4 MS medium with 3% sucrose and lacking growth regulators. Plants were successfully established in soil.

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Somatic embryos were obtained from immature zygotic embryos of Cedrela fissilis Well. (Meliaceae), after a culture period of 12 months, with regular subcultures every 6 -8 weeks. Callus was developed on explants in 2 months on Murashige and Skoog (MS) medium containing 2,4 dichlorophenoxyacetic acid (2,4-D) or picloram (PIC). When the calli were transferred to fresh medium, embryogenic tissue appeared on MS + 45 µM 2,4-D, or 22.5 µM 2,4-D + 0.4 µM 6-benzyladenine (BA), or 20.7 µM PIC after 6 months. Sub-culture of embryogenic tissue in MS medium supplemented with 4.5 µM 2,4-D resulted in the differentiation into somatic embryos after further 4 months. Repeated secondary somatic embryogenesis was achieved by regular subculture on this medium. Maturation and conversion of somatic embryos into plantlets was achieved on MS medium without plant growth regulators and the conversion frequency was approximately 12.5 %. The plantlets were successfully acclimatized in pots with soil. Histological studies showed that somatic embryos had no detectable connection with the mother explants and that somatic embryos in advanced stages were bipolar with shoot and root apical meristems, they contained vascular system and showed typical characteristics of a somatic dicotyledonous embryo.

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