The regeneration rate of plantlets cultivated via tissue culture is an important factor for wheat transformation. Similar to other monocotyledons, the most efficient tissue culture materials for wheat are immature embryos. However, stable year-round production of immature embryos is not possible in the field where various stress factors co-exist. In this study, we investigated the generation and subsequent plantlet incident rates of callus induced from immature embryos obtained from different sowing times in 2020 and compared these among wheat cultivars. We found that the rates of regeneration and plantlet incidence obtained using immature embryos of the Ariheuk cultivar were higher than those of other domestic cultivars, and that the tissue culture efficiency was similar to that of Bobwhite, which has been established as a cultivar with excellent transformation efficiency. Furthermore, the Baekkang cultivar showed high tissue culture efficiency only when sown from early to mid-March, whereas Keumkang showed higher tissue cultivation efficiency only by sowing in mid- and late February. Among the five cultivars assessed in this study, Jopum showed the lowest tissue culture efficiency. It is anticipated that the findings of this study will contribute to enhancing the transformation efficiency of domestic wheat varieties.

This study was carried out to establish the optimal conditions for callus induction and plant regeneration using immature inflorescence of M. sacchariflorus cv. ‘Wooram’, a bioenergy crop selected in Korea. Callus induction rate was the highest (93.3%) in MS medium containing 3 mg L^-1 2,4-D, and 86.7% in MS medium containing 3 mg L^-1 2,4-D combined with 0.1 mg L^-1 BA. Plant regeneration rate was high when the calli derived from the medium containing BA was used, as compared with those derived from the BA-minus medium. The results showed that the medium conditions containing 5 mg L^-1 BA combined with 0.1 mg L^-1 NAA was the most effective in plant regeneration of which the rate reached 86.7%. The regenerated shoots were separated from the calli and roots over 3 cm were developed from the shoots after 4 week culture on basal MS medium without supplementation. The plantlets were then transferred to soil and cultured in greenhouse. After 5 weeks, the plants with the height of at least 20 cm were successfully acclimatized.

We tried to develop the protocol for embryogenesis and plant regeneration from anther culture of carrot (Daucus carota L.) genotype ‘S&P2342’. Anthers were cultured on MS medium with B5 vitamins containing different combinations of 2,4-D and NAA for 18 weeks in the dark. The best induction of callus and embryo was obtained in the medium containing 0.1 mg/L 2,4-D and 0.1 mg/L NAA, on which 22.0% callus and 2.0% embryo were induced. When primary embryos induced directly from anther culture were transferred to the regeneration medium, secondary embryos were initiated from primary embryos after 4 weeks of culture and 62.5% converted into plantlets after 8 weeks of culture. The plantlets with true leaves were obtained after 12 weeks of culture. When the calli derived from anther culture were transferred to the regeneration medium, 38.8% of the calli produced primary embryos and plantlets after 8 weeks of culture. The plantlets with 2 or more leaves cultured on the regeneration under the different light intensity for the growth of in vitro plantlets. The plantlets cultured at 100 μmol·m^-2·s^-1 showed the highest growth rate. For the acclimatization, the in vitro plantlets with 4 or more leaves cultivated under the different light intensity and temperature, respectively. The survival rate and growth of plantlets was best at 15℃ and 100 μmol·m^-2·s^-1, respectively. The plants were successfully acclimatized and had a normal phenotype. The anther culture system could be used to prepare the doubled haploid lines as an appropriate breeding material for F₁ hybrid breeding program.

Plant regeneration protocols via adventitious shoot organogenesis from leaf segments of Chrysanthemum morifolium ‘Baekma’ were developed. The effects of plant growth regulators (BA, NAA, IBA, IAA and 2,4-D) and AgNO₃ were tested to figure out the optimal condition for shoot bud induction and shoot formation from leaf explants. On the combination treatment of plant growth regulators and AgNO₃, bud induction was obtained but shoot formation was not. Therefore, two-stage treatment of leaf explants was subsequently experimented for the respective improvement of adventitious bud induction and shoot formation. When leaf explants were cultured on bud induction medium (MS medium supplemented with 0.2 mg/L BA, 1.0 mg/L IAA and 1.0 mg/L 2,4-D) for 4 weeks in darkness and were transferred to shoot formation medium (MS medium supplemented with 1.0 mg/L BA, 1.5 mg/L IBA and 5.0 mg/L AgNO₃) for 4 weeks under the 16/8h photoperiod condition, shoot formation efficiency reached up to 50.0% and 1.6 shoots per explant were acquired. At 12 weeks after culture, the regenerated shoots were elongated and rooted on MS medium. The plantlets were acclimatized successfully and the regenerated plants exhibited normal phenotypes.