Plantlet Regeneration and Multiple Shoot Induction from Protocorm-Like Bodies (PLBs) of Medicinal Orchid Species, Dendrobium crumenatum Sw.

To investigate the suitable medium for in vitro shoot regeneration and plantlet growth of Dendrobium crumenatum Sw., individual protocorm-like bodies (PLBs) (about 4 - 5 mm in diameter) of Dendrobium crumenatum Sw. derived from MS medium supplemented with 0.5 mg/L TDZ for 60 days of culture were cultured on 6 culture media; Murashige and Skoog (MS) medium, MS medium supplemented with 15 % (v/v) CW, MS medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC, Vacin and Went (VW) medium, VW medium supplemented with 15 % (v/v) CW, VW medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC. After 4 months of culture, MS medium containing 15 % coconut water (CW) gave the highest percentage of shooting and number of shoots per explant of 96.0 and 9.5, respectively with a significant difference from other media. The addition of 0.2 % (w/v) activated charcoal (AC) significantly increased the number of leaves and roots. PLBs developed into complete plantlets. MS medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC and VW medium supplemented with 15 % (v/v) CW and 0.2 % (w/v) AC gave the highest number of roots per plantlet and root length at 5.3 roots and 34.9 mm, respectively. After the transfer of rooted shoots to the greenhouse, 95 % of the regenerated plantlets survived and grew vigorously. Plantlets grown in vitro were successfully acclimatized in the greenhouse and showed normal development.

Effects of Benzyladenine on in vitro ‘Hom Rangsi’ Rice and Induction of Aluminum Acid Tolerance Lines by Gamma Irradiation

‘Hom Rangsi’ was the non-photoperiod aromatic mutant rice which derived from fast neutron radiation KDML 105. ‘Hom Rangsi’ seeds were cultured on MS solid medium without any supplemented for a week. And then, all explants were placed on MS (Murashige and Skoog, 1962) medium supplemented with 0, 5, 10, 15, 20, 25 mg/L BA (benzyladenine) for multiple shoot induction. The optimal concentration of BA for induced multiple shoot induction of ‘Hom Rangsi’ line was MS + BA 25 mg/L, the highest number of shoots were 5.38 shoot/seed. The following experiment was done, irradiated ‘Hom Rangsi’ seeds with 0, 100, 200, 300, 400 Gy gamma ray which cultured on MS solid medium supplemented with 400 mg/L Al3+ pH 2.9 were selected for acid tolerance lines. After six weeks cultured, the survivals of irradiated plantlets were 86.32, 77.78, 58.95, 58.95, 21.87% and the height of irradiated plantlets were 8.4, 8.3, 6.7, 6.6, 6.1 cm respectively without any shoot budding. All survival plantlets were transferred to suitable MS + BA 25 mg/L medium which discovered from the first experiment for multiple shoot budding. After six weeks cultured, the maximum of 5.24 shoots/plantlet were found from 300 Gy irradiation significantly and followed by 400, 200, 0 and 100 Gy irradiation treatments which gave 4.55 and 4.41, 4.37 and 4.31 shoots/planlet respectively.

Multiple shoot induction in zygotic embryos: A strategy for acceleration of banana breeding

The presence of residual female fertility in most of the parthenocarpic banana accessions, embryo culture technique encourages the banana breeder to develop new hybrids through conventional breeding. Desirable trait can be fixed in banana in the first generation of hybrid progenies, but their evaluation is a long process owing to non-availability of uniform suckers/planting material. The duration of the breeding cycle can be reduced by developing more number of plantlets per hybrid event under in vitro embryo culture. Thus efforts were taken to standardize the multiple shoot formation from single embryo through media manipulation and decortications of embryo culture derived single plants. Success on multiple shoot formation was achieved up to 75% and 95% in seeded accessions of M.acuminata and M.velutina embryos respectively. In general, enhanced regeneration efficiency and rate of multiple shoot formation were recorded in media with BAP concentration of 17.76µm. Single in vitro plantlets derived through embryo culture were decorticated to 3 cubic cm size that resulted in 100% multiple shoot formations. This technique has been implemented from the seeds obtained from controlled pollination (18 cross combinations) and open pollination (nine accessions) of various genomic groups (ABB, AAB, AA) and their genetic fidelity of multiple shoots were also confirmed through microsatellite markers. As this technique, i) enhances the regeneration of hybrid seeds; ii) overcomes the risk of field mortality of the hybrid progenies and iii) allows simultaneous evaluation for multiple traits, will accelerate the breeding program by reducing the time taken for the release of potential banana hybrids.

High Efficiency In vitro Regeneration and Genetic Stability of Corallocarpus epigaeus - An Endangered Medicinal Plant

Indirect regeneration of plantlets from multiple shoot induction of Corallocarpus epigaeus was obtained from leaf and nodal explants on MS with different concentrations of BAP in combination with IAA/IBA or IBA alone. Among all the combinations, BAP and IBA exhibited maximum regeneration. High frequency of multiple shoots (89%) was obtained on BAP (2.0 mg/l) and IBA (1.5 mg/l) in nodal explants. Maximum mean shoot length of 6.8 ± 0.33 cm was obtained in nodal explants cultured on BAP (1.0 mg/l) + IBA (0.5 mg/l), followed by leaf explants with 6.7 ± 0.47 cm on BAP (3.0 mg/l) + IAA (2.5 mg/l). The highest frequency of rooting (88.3%) was obtained on NAA (1.0 mg/l) and IBA (2.0 mg/l) with 21.83 ± 0.57 mean number of roots. The well-rooted healthy plantlets were acclimatized with a survival rate of 80%. Inter simple sequence repeat (ISSR) analysis revealed the genetic similarity of in vitro raised plants with the mother plant. Plant Tissue Cult. & Biotech. 30(2): 219-229, 2020 (December)

Optimization of growth regulators on in vitro propagation of Moringa stenopetala from shoot explants

Background Moringa stenopetala belongs to the flowering family Moringaceae and genus Moringa. It is often referred to as the East African Moringa tree because it is native only to southern Ethiopia and northern Kenya. The expansion of its cultivation and utilization throughout the world especially in Africa is becoming important. For such expansion, the existing propagation method is limiting, so it needs a good propagation system to supply enough planting material with a uniform genotype. Therefore, the main objective of this study was to optimize an in vitro shoot multiplication protocol for M. stenopetala by using shoot tip as explants. Results Shoots were sterilized and cultured on Muraghige and Skoog (MS) medium for in vitro shoot initiation. For multiple shoot induction, the explants were cultured on MS medium supplemented with different concentrations of kinetin (0.5, 1.0, 1.5, 2.0, 2.5 mg/L) with Indole-3- butyric acid (IBA) or α -naphthalene acetic acid (NAA) (0.01, 0.1, 0.5 mg/L) and maintained at 25 ± 2 °C for four weeks. Rooting was achieved by culturing well developed shoots in half-strength MS medium containing IBA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L), NAA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L), and 0.5 mg/L IBA with NAA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L). Statistical analysis revealed that there was a significant difference among all treatments applied in both shoot multiplication and rooting experiments. The maximum number of shoots per explant (3.43 ± 1.41) and 7.97 ± 4.18 leaves per explant were obtained on MS medium containing 0.5 mg/L kinetin with 0.01 mg/LNAA. The highest mean number of roots per shoot (1.63 ± 1.03) and mean root length (0.87 ± 1.22 cm) were obtained on MS medium containing 1.0 mg/LNAA and 0.1 mg/LIBA alone respectively. After acclimatization, 76% of plants were survived in the greenhouse. Conclusion In general, using NAA with kinetin for shoot multiplication was effective than kinetin with IBA. On the other hand, the application of 1.0 mg/L NAA alone and 1.0 mg/L NAA with 0.5 mg/L IBA were more effective for root induction.