Plant regeneration of Ilex paraguariensis (Aquifoliaceae) by in vitro culture of nodal segments.

In vitro regeneration of complete plants from nodal single bud segments of "yerba mate" (Ilex paraguariensis St. Hil.) was studied under defined nutritional and environmental conditions. Nodal segments harvested from actively growing shoots of conventionally raised plants were cultured on nutrient medium with the mineral salts and vitamins of Murashige and Skoog medium at 1/4 strength, supplemented with various concentrations of sucrose and 6-benzyladenine (BAP). Shoot regeneration from explants of both young (2 years old) and adult (20 years old) mother plants were readily achieved in the medium supplemented with 0.04-0.09 M sucrose with or without BAP. As many as 60-65% of the nodal segments cultured formed shoots. Rooting of regenerated shoots was observed in 50% of the explants harvested from young plants, whereas 25% of the explants rooted when the nodal explants were harvested from adult plants. The best rooting induction was achieved on 1/4 strength MS medium with vermiculite as the substrate and supplemented with 1-1.5% IBA (indolebutyric acid) and 1-2% PPZ (3-methyl-1-phenyl-2 pyrazolin-5-one). Plantlets were successfully transferred to soil.