Optimization of Clonal Micropropagation Stages of Lilium pensylvanicum Using Crezacin: In Vitro Rooting and Ex Vitro Acclimatization

The current challenges associated with the conservation and restoration of plant biodiversity make it necessary to test new biotechnological approaches. Optimizing the stages of clonal micropropagation using synthetic growth biostimulants—protatranes (1,2,3)—enables the targeted modification of physiological processes in plants. This increases their stress resistance, stimulates development, and reduces the cost of the final product. In this paper, the stimulating effect of the protatran (1), which we have named “crezacin”, on the processes of in vitro rooting and acclimatization to ex vitro conditions in microplants of the rare wild species Lilium pensylvanicum Ker Gawl was studied. No effect of crezacin and α-naphthylacetic acid on the development and growth of the microbulb during the rooting stage was detected. Crezacin at a concentration of 1.0 mg/L inhibited root elongation, but did not affect root number. Using α-naphthylacetic acid at a concentration of 0.93 mg/L was ineffective in inducing in vitro rhizogenesis. The survival rate of regenerated plants cultivated on media supplemented with crezacin was found to be 100%. The positive effect of crezacin on the content of photosynthetic pigments in the leaves of regenerated plants was also demonstrated. The addition of ultra-low concentrations (0.001–0.1 mg/L) of crezacin increased pigment content by up to 1.5 times (p < 0.05) compared to the control group. The increase in chlorophyll and carotenoid levels upon the addition of crezacin to the culture medium significantly facilitated the transition from a heterotrophic to an autotrophic mode of nutrition when microplants were transplanted into a soil substrate. Further research on clonal micropropagation of rare plant species and horticultural crops will be conducted using protatranes 2 and 3.