Micropropagation Shortens the Time to Blooming of Begonia montaniformis × Begonia ningmingensis var. bella F1 Progeny

Abstract

Begonia montaniformis × Begonia ningmingensis var. bella hybrids have high ornamental potential. Hence, the aim of this study was to determine the optimal conditions for the micropropagation of a Begonia montaniformis × Begonia ningmingensis var. bella F1 progeny by using various concentrations of plant growth regulators (PGRs) and varying light spectra in half-strength Murashige and Skoog (1/2 MS) medium. The results showed that the explant regeneration was optimal when the lamina was incubated in a medium supplemented with 2.0 μM N6-benzylaminopurine and 0.8 μM α-naphthaleneacetic acid (NAA). Under such conditions, 98% of the explants regenerated adventitious shoots after 8 weeks, and 41 buds were produced per explant on average. The mean shoot length was 9.6 mm, and on average, 4.5 shoots per explant were more than 2 mm long. Subsequently, the induced adventitious shoots were transferred into rooting medium consisting of 1/2 MS and various NAA concentrations. After 4 weeks, the shoots subcultured in this medium showed ≈93% root induction and an average of 3.5 adventitious roots per explant. Furthermore, the applied light spectrum significantly influenced shoot regeneration, and optimal results were achieved under an equal distribution of blue, red, and infrared light. The histological sections of shoots regenerated from direct organogenesis were observed through scanning electron microscopy (SEM). Afterward, the rooting adventitious shoots were subcultured in PGR-free medium for 8 weeks. The seedlings were successfully acclimated 4 weeks after being transferred to soil and bloomed after 11 months in a greenhouse. Thus, the PGR composition in micropropagation efficiently shortened the time to blooming from 25 to 16 months.