The study aimed at evaluating the response of common plum (Prunus domestica L.) microshoots during in vitro rooting in the presence of two phytoactive medium supplements, i.e. a dialyzate of pineapple pulp and a conditioned medium containing green algae Desmodesmus subspicatus exudates. Rooting efficiency was evaluated after 4 weeks of culture. During the root induction phase the content of phenolic compounds in shoot bases was determined and anatomical studies were conducted. Medium supplements were analyzed for the content of carbohydrates and phenolic acids. Both supplements were efficient in rooting induction of shoots of a difficult-to-root cultivar ‘Węgierka Zwykła’. Medium supplementation allowed a significant reduction in the exogenous auxin content required for rooting. The highest rooting efficiencies on supplemented media were 28.9 and 27.8 %, in comparison with 33.3 % obtained in the control medium with doubled concentration of exogenous auxins. In the easy-to-root plum cultivar ‘Węgierka Dąbrowicka’ the rooting rate was slightly reduced in the presence of pineapple dialyzate, while in the presence of algal conditioned medium the rooting rate decreased substantially compared with the non-supplemented medium. Approximately 30 % of ‘Węgierka Dąbrowicka’ shoots rooted on supplemented auxin-free media. The content of phenolic compounds accumulated in shoot bases during the root induction stage reflected the differences in rooting ability between both plum cultivars, indicating potential stressful conditions of the culture generated by the presence of phytoactive natural supplements. Anatomical study allowed to recognize the mode of dedifferentiation leading to adventitious rhizogenesis in the common plum. The results are discussed in relation to the composition of medium supplements and their potential root-promoting activity.

Generative processes have been evaluated in six European buttercup species in order to verify the hypothesis that the reproduction efficiency of clonal species is lower than that of nonclonal ones. The study covered common species (Ficaria verna, Ranunculus auricomus, R. bulbosus, R. cassubicus, R. lanuginosus) and the endangered R. illyricus. The following properties have been assessed: pollen viability (staining method), pollen grain germination and the pollen-tube elongation in pistil tissues (fluorescence microscopy), seed formation efficiency, seed viability (tetrazolium test) and germination ability by introducing factors interrupting dormancy (low temperature and gibberellin application). Additionally, the pistil morphology was documented for R. bulbosus, R. illyricus and R. cassubicus using SEM techniques. It was demonstrated that the reproductive efficiency, expressed as the production of viable seeds able to germinate, was significantly higher in the species reproducing sexually (especially in R. lanuginosus) compared to the clonal ones. However, the complexity observed leads to separation of an additional group (cluster) of apomictic species: R. auricomus and R. cassubicus, distinguished by the lowest pollen viability and a low ability of the seeds to germinate. In the vegetatively reproducing R. illyricus, the seed formation efficiency was just 13.2% despite the having highest number of pistils in its flowers. The developed seeds of this species observed in our experiment were viable, but in general effective methods to stimulate their germination have not been proposed yet. Here, the first comparative study concerning the biology of sexual reproduction of R. illyricus is presented in the context of its decreasing distribution in natural habitats.

Pontechium maculatum, a species of ornamental, apicultural, health and medicinal value, is threatened in some Central European countries including Poland. Its propagation using seeds or in vitro techniques is needed for multiple applications including conservation. Generative propagation efficacy of P. maculatum plants representing different genetic resources (received from botanical gardens in Germany and in Poland) propagated from seeds or in tissue culture was assessed. Moreover, an efficient technique of propagation of P. maculatum using in vitro shoot culture from seedlings was elaborated for the first time. The highest propagation efficacy was noted for German plants of seed origin. The ability of seeds to germinate was similar for all plants; however, seeds were in a state of dormancy, which was broken by GA₃. After two years of storage, the seeds still retained the ability to germinate though seeds from propagated in vitro plants germinated more poorly than those from seed-originated plants. The ploidy assessment showed that some in vitro-origin plants had altered DNA content. The results indicate that efficacy of generative propagation of P. maculatum is resource dependent. Furthermore, results suggest that cultivation in vitro influenced some generative features of examined species, which makes this way of P. maculatum propagation a valuable source of genetic variation and a potential breeding tool.

Our study aimed at active conservation of the last location of Primula farinosa, an endangered species in Poland, and assessed reproduction by seeds and plant propagation on sterile media in tissue culture conditions. We identified gibberellic acid (GA3) as the key factor stimulating germination of P. farinosa seeds. Growing juvenile plants under controlled temperature of 18/16 °C day/night yielded good quality plant material without mycorrhization. In tissue culture, the most favorable medium for shoot propagation was MS supplemented with the lowest tested concentration of indole-3-butyric acid (IBA; 0.05 mg dm−3) and 6-benzyl-aminopurine (BAP; 0.1 mg dm−3). The rooting ability of shoots was high and comparable for all auxins used. 2C DNA content of seed-derived and micropropagated plants did not indicate any change in the ploidy level during in vitro cultivation. Plants derived from seeds and tissue cultures were compared in a 2-year study. Of all the characteristics compared, only the number of flowers per inflorescence was lower for micropropagated plants when compared with the seed-origin plants in the first year of observation. The difference was of transient nature and was not observed in the second year of the study. Effective protocols for in vivo and in vitro propagation of P. farinosa were developed, which can be used in practical species protection.

The bird’s-eye primrose (Primula farinosa L.) is an endangered species in Poland. The sole remaining, and critically endangered, population of approximately 300 flowering plants is located in the Beskid Sądecki Mountains (Jaworki, Poland). The genetic investigation was performed using highly variable microsatellite markers on a total of four populations: the Polish population and its three nearest known Slovak counterparts. We hypothesize that the Polish population is a relic of the previously much wider Central European mountain/lowland range and is thus genetically distinct from the rest of the Slovak stock. Clarification of this issue is needed before active protection interventions such as artificial supplementation can be carried out. Our results, particularly those from STRUCTURE Bayesian clustering, showed clear population structure within the dataset: all three Slovak populations were dominated by one genetic group, while the Polish population comprised mostly individuals dominated by the second genetic group. Only limited gene flow was observed between the Polish and Slovak populations. This demonstrates the distinct genetic makeup of the Jaworki population, which is probably the result of prolonged isolation from the rest of the P. farinosa range and admixture of genes from various lineages. Their origin could be determined by including plant material from the rest of the P. farinosa range, i.e., Scandinavian, Baltic, and Alpine/Carpathian locations, in a future study. The immediate practical application of our results is the recommendation that all supplementation interventions to the Jaworki population must be limited to plants produced from locally collected seeds.