Inflorescence proliferation for somatic embryogenesis induction and suspension-derived plant regeneration from banana (Musa AAA, cv. 'Dwarf Cavendish') male flowers

Effects of light intensity and plant growth regulators on callus proliferation and shoot regeneration in the ornamental succulent Haworthia

BACKGROUND

Haworthia are desert succulents belonging to the Asphodelaceae family. Haworthia species are cultivated commercially as ornamentals and some rare species are quite valuable at retail market but growth slowly and difficult to propagation. However, an efficient micropropagation protocol was remained insufficient.

RESULTS

The organogenic cultures obtained from inflorescence explants were cultured on Murashige and Skoog (MS) medium supplemented with various combinations of 6-benzylaminopurine (BA) and α-naphthalene acetic acid (NAA) under a light intensity of 10 μmol m^-2 s^-1 or 45 μmol m^-2 s^-1. The highest callus proliferation index (93.15%) with 1.0 mg L^-1 BA + 0.1 mg L^-1 NAA under a light intensity of 10 μmol m^-2 s^-1. The best shoot proliferation rates were on media with either 1 mg L^-1 BA + 0-0.4 mg L^-1 NAA (65.57-81.01%) under a light intensity of 45 μmol m^-2 s^-1. The highest root length (15.57 mm) and the highest rooting frequency (17 roots per shoot) were obtained when adventitious shoots were inoculated on MS medium with 0.4 mg L^-1 NAA + 0.4 mg L^-1 IBA. The survival rate of the transplanted plantlets was about 100%. The efficient micropropagation protocol proliferated Haworthia regenerate plants from inflorescence within 11 weeks.

CONCLUSIONS

The present study determined the best combination of light intensity and plant growth regulators (PGRs) for improved organogenesis of Haworthia during propagation by tissue culture. This optimized protocol showed light intensity is an important factor for efficient callus or shoot regeneration. These results indicate that it will be useful to optimize the light conditions for future commercial cultivation, germplasm conservation, genetic engineering and molecular biology research of this ornamental plant.

In Vitro Proliferation of Female Buds for Induction of Somatic Embryogenesis from False Horn Plantain (AAB, cv. Curraré)

Most cultivated bananas (Musa spp.) are polyploids, and their fruits are seedless and propagated exclusively vegetatively; however, they can also be cloned by micropropagation techniques, viz., direct organogenesis (DO) or somatic embryogenesis (SE). Banana indirect SE (ISE), with an embryogenic callus phase, is possible using young male or female flowers as direct explant depending on the genotype or shoot tips (scalps). For the False Horn Plantain, cv. Curraré (AAB, plantain subgroup), which has a degenerating male bud, female flowers are used to regenerate plants through ISE. Here, a protocol for increasing the number of initial explant material from a single mother plant and its embryogenic response is described. For those purposes, hands with young female buds are in vitro proliferated in the presence of 1 μM indole-3-acetic acid and 2.5 μM thidiazuron. Friable embryogenic cultures, here called ISE-2, obtained from the new proliferative secondary female bud clusters are initiated on medium containing auxins. Embryogenic suspensions are then established from the ISE-2 cultures. Regeneration of plants is achieved from embryogenic suspensions after plating on semisolid medium free of plant growth regulators; greenhouse acclimatized plantlets are ready for banana farming. This study demonstrates that proliferative female buds are a proper choice for ISE.