Evaluation of Factors Affecting Direct Organogenesis in a Somatic Tissue Culture of Sinningia speciosa (Lodd.) Hiern

In this study, the influence of genotype, concentration of thidiazuron (TDZ), and explant position on the culture medium in organogenesis in a somatic tissue culture of two gloxinia cultivars was investigated. Isolated explants cultured on the medium containing TDZ formed adventitious shoots directly without an intervening callus phase. Explant regeneration frequency varied depending on the genotype, TDZ concentration, and explant position on the medium. The analysis of variance revealed that cultivar (C), TDZ concentration (T), position of explant on culture medium (P), and the interaction of C × T, C × P, T × P, and C × T × P significantly influenced the frequency of shoot formation. However, the effect of interface C × P and C × T × P on the number of shoots per explant was not significant. “Snowy” leaf explants manifested a significantly higher mean shoot formation frequency (p ˂ 0.01) in comparison with the cultivar “Midnight Purple”. The medium enriched with 3.5 μM TDZ resulted in the highest organogenesis frequency, while the highest shoot number per explant was acquired on medium supplemented with 4.0 μM TDZ. The explants of the tested cultivars cultured on the medium with the adaxial side down showed a significantly higher (p ˂ 0.01) shoot formation frequency in comparison with explants cultured on the medium with the abaxial side, and they showed a higher mean number of shoots per explant. An effective method for in vitro organogenesis of Sinningia speciosa (Lodd.) Hiern without an intervening callus phase was established.