A Novel Regeneration System for Tamarillo (Cyphomandra betacea) via Organogenesis from Hypocotyl, Leaf, and Root Explants

Abstract

Cyphomandra betacea (Cav.) is commonly known as Tamarillo or tree tomato. This species is mainly used for its edible fruits which have a high nutritional value and contain relatively high amounts of proteins, vitamins B6, C, E, and provitamin A. The cultivation of Tamarillo in Rwanda is facing major challenges caused mainly by viral diseases such as Tamarillo mosaic virus (TaMV). These diseases are difficult to control and are transferred through vegetative propagation, often resulting in heavy productivity losses and poor-quality fruits. Thus, this study was conducted to evaluate the possibility of using tissue culture as an alternative propagation method. Tamarillo seeds were sterilized using a commercial bleach and germinated in vitro to get clean starting explants. Explants (hypocotyls, leaves, and roots) were cultured on semisolid Murashige and Skoog (MS) media supplemented with 6-benzylaminopurine (BA), N6-2-isopentyl adenine (2iP), 6-furfurylaminopurine (kinetin) evaluated at 5, 10, 20, 40 µM, and thidiazuron (TDZ), evaluated at 0.1, 0.5. 1.0 1.5 µM in separate experiments. Data were collected on the number of microshoots and roots 2 months after culture and analyzed using the Statistical Software for Social Sciences (SPSS) Software version 8. The results showed that the growth regulators evaluated had a significant (P ≤ 0.05) effect on plantlet regeneration from leaf and hypocotyl explants. The media supplemented with BA 40 μM was the most effective in inducing multiple shoots from leaf explants producing 4.67 ± 0.15 shoots per explant. Root explants showed the least morphogenic responses for all the parameters evaluated. The regenerated plantlets were transplanted to the greenhouse and a survival rate of 90% was recorded. During this study, a simple, reproducible, single-step protocol was developed. These results would be useful for mass propagation of Tamarillo.