The aim of this paper was to develop a protocol for efficient storage of artificial seeds of Taraxacum pieninicum, critically endangered Asteraceae species. Storage under reduced light conditions or in the darkness was tested on a basis of synthetic seeds ability to conversion and post-storage regrowth of shoot tips. The results indicated that synseeds obtained from shoot tips of T. pieninicum can be stored at 4 A degrees C even for 12 months without subculture. The light is a stress factor during storage what was manifested by numerous necrosis and decreased shoots ability to proliferate in optimal growth conditions in 1st subculture. Additionally our results showed that the storage does not produce genetic variation at the resolution provided by the flow cytometry and RAPD analysis.

Advances in biotechnology, especially in the field of in vitro culture techniques, led to the development of procedures that can be used as an excellent tool in plant conservation. The present study describes in vitro conservation of Senecio macrophyllus by slow-growth storage. Various sugar treatments, concentration of abscisic acid (ABA), light intensity and type of containers were tested. Viability and proliferation rate of shoots were evaluated 4 weeks after regrowth. The results obtained showed that polycarbonate boxes were a better type of containers for storage of S. macrophyllus shoots than glass vessels. Light negatively affected culture viability, multiplication rate and rooting response. In the case of Senecio macrophyllus the addition of ABA to storage medium stimulated survival and higher proliferation of shoots during regrowth in optimal conditions in comparison to shoots stored on medium without ABA. Shoots of S. macrophyllus were effectively stored for 6 months. All rooted shoots survived adaptation to field conditions and were able to flower in the second year after acclimatization.

Taraxacum pieninicum is an extremely threatened species. It seems that traditional protection methods of this species are insufficient and it is necessary to use biotechnology tools that allow the in vitro storage of plant material. The present study describes in vitro conservation of T. pieninicum by slow-growth storage. Various light conditions and abscisic acid (ABA) treatments and combinations thereof were tested. Viability, proliferation rate and ability of shoots to root were evaluated during regrowth. Moreover, the effect of shoot storage conditions on the ABA level was analysed. The results showed that light during 3-months’ storage increased the level of endogenous ABA. Similar results were observed when storage at a low temperature was prolonged to 9 months. Changes in ABA level had a negative effect on shoot condition. However, these changes were related to leaves and did not affect the ability of shoot tips to proliferate after long-term storage. Addition of ABA to storage medium increased several folds the level of ABA in plant tissues, which resulted in a reduction in the visual rating and proliferation rate. Shoots obtained after post-storage regrowth were able to root. All rooted shoots survived adaptation to field conditions and were able to flower in the second year after acclimatization. The analysis of DNA content indicated that all the regenerants had the same ploidy level independent of treatments during storage. Cold storage of T. pieninicum as used in this study enabled the interval between subcultures to be extended to 9 months.

Jasmonic acid is involved in plants response to various abiotic and biotic stresses. The aim of this study was to examine physiological response of Taraxacum pieninicum to JA-treatments during shoots micropropagation and during cold storage at 4 °C under reduced light or in the darkness. Obtained results indicated that JA during preculture reduced significantly growth of shoots without impact on proliferation rate. During cold storage JA (24–72 µM) limited effect of cold stress what was manifested by reduced accumulation of proline and TBARS. Growth inhibition of the stored tissue was more effective when JA was inside synthetic seeds structure than after preculture on medium supplemented with JA. Shoot proliferation and rooting were effective during regrowth after cold storage combined with JA exposure. Only elongation of roots was inhibited after storage in this conditions. However, length of roots did not affect acclimatization of plantlets to ex vitro conditions.

Taraxacum pieninicum Pawł. is listed as critically endangered species, for which currently applied protection methods are insufficient. The aim of this study was to investigate the possibility of T. pieninicum storage in the form of synthetic seeds under slow-growth conditions in combination with ABA treatment, as one of the ex situ protection methods of this species. The obtained results indicated that darkness was much more favorable condition for synseed storage and did not generate additional stress during cold exposure in contrast to the light conditions. The preculture of shoot tips on the medium supplemented with ABA led to a decrease in the shoots proliferation rate and inhibition of their growth. ABA clearly inhibited growth of the encapsulated shoot tips also during cold storage. Biochemical parameters showed that ABA effectively reduced the negative effect of the cold stress, what was found on the basis of analyzes of H₂O₂ and TBARS levels in the stored material. Moreover, synseeds stored under light conditions and treated with ABA exhibited decreased level of endogenous jasmonic acid what indicated interaction between those two phytohormones at a low temperature. The study also demonstrated that in vitro culture, cold storage and ABA treatment had no effect on the flowering process of this species after acclimatization to ex vitro conditions.