An efficient micropropagation system for Taraxacum pieninicum using seedling explants germinated in vitro is described. Shoot tips and fragments of cotyledons, hypocotyls and roots were isolated from several-day-old seedlings. The highest response, 100% frequency with 12.3 axillary shoots/explant, was from shoot tips on medium supplemented with 0.5 mg L-1 BA and 0.05 mg L-1 NAA. In subsequent subcultures the number of shoots was significantly higher on all explants cultured on medium containing 0.25 and 0.5 mg L-1 BA, and the multiplication rate was highest (20 shoots/explant) in the 4th passage. Shoots rooted on MS and 1/2 MS medium; the highest rooting frequency was 90% and the highest number of roots 2.7/shoot. Rooted plants showed 96.2% survival in sterile soil:sand, and 100% survival in hydroponic culture. Regenerated plants flowered in the second year after acclimatization and yielded viable seeds. This protocol for obtaining complete plants through micropropagation may prove useful for conservation of the genetic resources of this and other endangered species.
Regenerated plants of Carlina acaulis subsp. simplex induced on shoot tips and fragments of hypocotyls, cotyledons and roots were used as an experimental material. Explants were isolated from 10-day-old, sterile seedlings and were put on growth media supplemented with BA(3 mg × dm⁻³), andNAA(0,l mg × dm⁻³). Plantlets were acclimatized to ex vitro conditions and planted to the field. Analysis of flowering ability, inflorescence stem morphology, and survival level was the objective of the study. The plants regenerated from shoot tips and cotyledons were able to flower in the first year after acclimatization, however no vital seeds were found, while in the case of hypocotyl- and root-regenerated plants flowering appeared in the second year after acclimatization. Number of flowering-able plants grew in time, reaching 100% level. Few percent of inflorescence stems displayed branches ending with additional capitula. The number of this type of plants decreased in successive years, while the average length of inflorescence stem increased. In the case of intensively flowering plants, the survival rate decreased in 3 consecutive years.
Various explants from 30-day-old seedlings of Centaurium erythraea Rafn were evaluated for their morphogenetic capacity under in vitro culture conditions. Shoot formation from shoot tip explants was achieved mainly through adventitious bud differentiation. The highest number of shoots (up to 43.3 ± 2.2 from a single shoot tip) was obtained on Murashige and Skoog medium (MS) supplemented with indole-3-acetic acid (IAA) (0.57 μM) and 6-benzylaminopurine (BAP) (4.4 μM). Adventitious shoot regeneration was also achieved through organogenesis from calluses obtained from hypocotyls, cotyledons, roots and leaves on MS medium containing IAA (2.85 μM) and BAP (0.88 μM). Significant differences were noted between explant types in their effects on shoot regeneration. In the primary culture, the best response was obtained either from calluses derived from roots or leaves (44.4 ± 4.5 and 40.2 ± 6.0 shoots per callus, respectively). The number of subcultures of inoculated calluses affected both the multiplication rate (the number of shoots/explant) and shoot morphology (the frequency of shoot hyperhydricity). Shoots rooted with the frequency of 94-100% after culture on MS medium without growth regulators. Plantlets were successfully acclimatized (97%) under high relative humidity and then moved to the greenhouse.