Background : Platycodon grandiflorum has been used as food material and a traditional medicine in Korea. In order to develop an efficient in vitro micropropagation technique for a rare plant species and conservation for inbred line of plant breeding. Methods and Results : Plant regeneration via organogenesis and somatic embryogenesis was investigated in Platycodon grandiflorum. Leaf, stem, root tissues of 7-day-old seedlings were cultured on 1/2MS medium containing various concentration (0, 0.5, 1 and 2 ㎎/L) of IBA, BA and NAA. The results showed that 1/2MS medium supplemented with BA+NAA 2.0 ㎎/L yielded the highest callus formation ratio of 73.5%. When various tissues (leaf, stem, root) were tested on 1/2MS medium containing BA 2.0 ㎎/L+ NAA 2.0 ㎎/L for somatic embryogenesis, the optimum tissue for embryogenic shoot induction was stem tissue. Callus were cultured on MS medium containing various concentration (0, 0.5 and 1 ㎎/L) of BA and NAA. The best rooting rate was achieved by three different medium (B5, 1/2MS and MS) and 1/2MS medium cultured the highest rooting ratio (82%). Conclusion : This study suggested that above micropropagation techniques can be used for rapid multiplication as well as in vitro or in vivo conservation of the Platycodon species.

Plant regeneration via organogenesis and somatic embryogenesis was investigated in Korean soybean cultivars including Cheongja 3, Jinpumkong 2, Taekwangkong and Uram. Cotyledon, cotyledon+hypocotyl and hypocotyl segments of 7-day-old seedlings were cultured on MS medium containing various concentration (0, 1, 2 and 4 ㎎/L) of BA and TDZ. The results showed that MS medium supplemented with BA 2.0 ㎎/L yielded the highest shoot formation ratio of 83.3%. In 4 cultivars, Taekwangkong showed the highest ratio of shoot formation. When various sizes of immature cotyledons (S: 1∼ 2 ㎜, M: 3∼5 ㎜, L: 6∼8 ㎜) were tested on MS medium containing 2,4-D 40 ㎎/L for somatic embryogenesis, the optimum size for embryogenic callus induction was 3∼5 ㎜ in length of immature cotyledons. In 4 cultivars, Taekwangkong showed the highest percentage of embryogenic callus induction. The results indicate that Taekwangkong is the best soybean cultivar for plant regeneration via organogenesis and embryogenic callus induction among the 4 cultivars.

Study question: What is the optimal vitrification protocol according to the cryoprotective agent (CPA) for ovarian tissue (OT) cryopreservation? Summary answer: The two-step protocol with 7.5% ethylene glycol (EG) and 7.5% dimethyl sulfoxide (DMSO) for 10 min then 20% EG, 20% DMSO and 0.5 M sucrose for 5 min showed the best results in mouse OT vitrification. What is known already: Establishing the optimal cryopreservation protocol is one of the most important steps to improve OT survival. However, only a few studies have compared vitrification protocols with different CPAs and investigated the effect of in vitro culture (IVC) on vitrified–.warmed OT survival. Some recent papers proposed that a combination of CPAs has less toxicity than one type of CPA. However, the efficacy of different types and concentrations of CPA are not yet well documented. Study design, size, duration: A total of 644 ovaries were collected from 4-week-old BDF1 mice, of which 571 ovaries were randomly assigned to 8 groups and vitrified using different protocols according to CPA composition and the remaining 73 ovaries were used as controls. After warming, each of the eight groups of ovaries was further randomly divided into four subgroups and in vitro cultured for 0, 0.5, 2 and 4 h, respectively. Ovaries of the best two groups among the eight groups were autotransplanted after IVC. Participants/materials, setting, methods: The CPA solutions for the eight groups were composed of EDS, ES, ED, EPS, EF, EFS, E and EP, respectively (E, EG; D, DMSO; P, propanediol; S, sucrose; F, Ficoll). The IVC medium was composed of a-minimal essential medium, 10% fetal bovine serum and 10 mIU/ml follicle-stimulating hormone (FSH). Autotransplantation of vitrified–.warmed OTs after IVC (0 to 4 h) using the EDS or ES protocol was performed, and the grafts were recovered after 3 weeks. Ovarian follicles were assessed for morphology, apoptosis, proliferation and FSH level. Main results and the role of chance: The percentages of the morphologically intact (G1) and apoptotic follicles in each group at 0, 0.5, 2 and 4 h of IVC were compared. For G1 follicles at 0 and 4 h of IVC, the EDS group showed the best results at 63.8 and 46.6%, respectively, whereas the EP group showed the worst results at 42.2 and 12.8%, respectively. The apoptotic follicle ratio was lowest in the EDS group at 0 h (8.1%) and 0.5 h (12.7%) of IVC. All of the eight groups showed significant decreases in G1 follicles and increases in apoptotic follicles as IVC duration progressed. After autotransplantation, the EDS 0 h group showed a significantly higher G1 percentage (84.9%) than did the other groups (42.4–.58.8%), while only the ES 4 h group showed a significant decrease in the number of proliferative cells (80.6%, 87.6–.92.9%). However, no significant differences in apoptotic rates and FSH levels were observed between the groups after autotransplantation. Limitations, reasons for caution: The limitation of this study was the absence of in vitro fertilization using oocytes obtained from OT grafts, which should be performed to confirm the outcomes of ovarian cryopreservation and transplantation. Wider implications of the findings: We compared eight vitrification protocols according to CPA composition and found the EDS protocol to be the optimal method among them. The data presented herein will help improve OT cryopreservation protocols for humans or other animals.

The efficiency of in vitro regeneration of four clones of Populus euramericana, Canada blanc, Eugenii, I-45/51, and Wisconsin #5, was examined. Cytokinins and the combinations with auxins affected the rate of regeneration from the explants of root segments, stem internodes, and leaf discs. Overall, BA and the combination with auxins were effective in root segments and leaf discs of the Canada blanc clone, whereas zeatin and the combination with auxins were important in stem internodes of the Wisconsin #5 clone. The highest number of shoots averaging 17.6 ± 0.47 from root segments in the Canada blanc clone,18.2 ± 3.0 from stem internodes in the Wisconsin #5 clone, and 17.8 ± 1.92 from leaf discs in the Canada blanc clone were obtained with 2.0 mg/1 BA, 2.0 mg/l zeatin combined with 0.2 mg/l IAA, and 0.5 mg/l BA combined with 0.05 mg/l 2,4-D, respectively. In particular, the addition of 2,4-D into cytokinin medium promoted shoot proliferation.

Aloe in vitro culture was attempted to induce callus and regeneration ability from different explant sources onto MS medium with 0.5mg/l NAA plus 1.0mg/l BA. Anthers that no developed any callus and plant regeneration, while only four out of 274 filament explants induced calli at cut edge without regenerated plants. Twenty ovary explants regenerated four direct plantlets without via callus from the base of epidermal tissues. Regenerated plants on the root tip gave 2n=14 of chromosome numbers.

콩에서의 조직배양 가능성을 알아보고자 콩 유묘를 기내에서 배양시킨 뒤, 여러 부위를 채취하여 각기 다른 배지 치상한 결과는 다음과 같다. 1. 줄기정단조직 배양에서는 대부분 shoot가 분화되어 완전한 식물체를 얻을 수 있었다. 2. 자엽절 조직배양에서는 multiple shoots가 나타나 대량증식에 유용했으나 배지에 따른 영향이 컸다. 3. 배축 및 상배축 조직배양에서는 callus만 분화되엇다. 4. 엽조직배양에서는 callus 분화 후 계대배양했을 때 shoot가 분화되었으나 완전한 식물체를 얻기는 힘들었다.