Morpho-Physiological Evaluation of Solanum betaceum Cav. In Vitro Cloned Plants: A Comparison of Different Micropropagation Methods

Tamarillo (Solanum betaceum Cav.) is a subtropical solanaceous tree with increasing agronomic interest due to its nutritious edible fruits. Growing demand for tamarillo plants and fruits requires optimization of existing propagation methods and scaled-up systems for large-scale cloning of selected germplasm. Three in vitro protocols have been used to micropropagate tamarillo: (1) axillary shoot proliferation in a semisolid medium, (2) organogenesis, and (3) somatic embryogenesis procedures. Variables such as the age of the established shoot cultures and rooting treatments were also analyzed. The morphological and physiological quality of acclimatized plants derived from all the methodologies were compared, with seed-derived plants used as a control group. Overall, the results show that in vitro-derived plants have a similar development to seed-derived plants. Micropropagation by axillary shoot proliferation was highly efficient, with rooting rates above 80% in most treatments. Organogenesis induction was more effective from lamina explants using MS media with 2.0 mg·L(−1) 6-benzylaminopurine. Both organogenesis and somatic embryogenesis-derived plants were also morphologically and physiologically equivalent to seed and axillary shoot-derived plants. The specificities of each micropropagation method are discussed.