An efficient micropropagation protocol for Rheum rhabarbarum L. was developed in this study. The in vitro rhubarb plants obtained in the multiplication stage (proliferation rate: 5.0 ± 0.5) were rooted in vitro (96% rooting percentage) and acclimatized ex vitro in floating perlite, with 90% acclimatization percentage. To assess the genetic fidelity between the mother plant and in vitro propagated plants, sequence-related amplified polymorphism (SRAP) markers were used. All banding profiles from the micropropagated plants were monomorphic and similar to those of the mother plant indicating 100% similarity. Regarding the polyphenolic profile, gallic, protocatechuic, p-hydroxybenzoic, vanillic, chlorogenic, caffeic, syringic, p-coumaric and ferulic acid were present in different amounts (2.3–2690.3 μg g⁻¹ dry plant), according to the extracted matrix. Aglicons and glycosides of different classes of flavonoids were also identified. The rhizome extracts (both from in vitro and field grown plants) contained resveratrol, a stilbene compound with high antioxidant properties, ranging between 229.4 to 371.7 μg g⁻¹ plant. Our results suggest that in vitro propagation of Rheum rhabarbarum L. represents a reliable alternative to obtain a large number of true-to-type planting material with high bioactive compound content of this valuable nutritional and medicinal species.

The demand for virus-free hop planting material has increased in the last few years due to its multipurpose uses. The present study aimed to establish an effective protocol for clonal propagation of cv. Cascade using only the cytokinins as PGRs in all stages of micropropagation: (i) in vitro culture initiation using single-node micro-cuttings inoculated on modified Murashige and Skoog (MSm) medium solidified with Plant agar and supplemented with 0.5 mg L⁻¹ 6-benziyladenine (BA) with 76% recorded viability of nodal explants; (ii) in vitro multiplication of multinodal shoots on MSm medium gelled with Plant agar and supplemented with different types and concentrations of cytokinins: 2 mg L⁻¹ kinetin (KIN), 0.7 mg L⁻¹ 1-(2-Chloro-4-pyridyl)-3-phenylurea) (1 CPPU), 2 mg L⁻¹ meta-topoline (mT) and 0.5 mg L⁻¹ BA, which was the best variant for shoot proliferation (9.48 ± 0.78 shoots/explant); (iii) rooting and acclimatization with the best results obtained by ex vitro rooting and acclimatization of plants in the same stage in perlite (96.00 ± 0.60% acclimatized rooted plants with 100% survival under greenhouse conditions). The true-to-type nature of in vitro raised plants with the mother plant was assessed by Random Amplified Polymorphic DNA (RAPD) and Start Codon Target Polymorphism (SCoT) molecular markers, and then their genetic uniformity were confirmed.

Micropropagation has an important role in the large-scale production of blackberry plant material, given the high proliferation rates of this species. The aim of the present study was to evaluate the proliferative capacity of blackberry grown in vitro on wheat starch-gelled culture medium compared to classical agar-gelled medium and to assess the genetic fidelity between the proliferated shoots in starch-gelled culture medium and their mother plants. Six blackberry varieties (‘Čačanska Bestrna’, ‘Chester Thornless’, ‘Driscoll’s Victoria’, ‘Loch Ness’, ‘Polar’, and ‘Karaka Black’) were tested. For the in vitro shoots proliferation, Murashige and Skoog (MS) medium supplemented with 0.5 mg dm⁻³ 6-benzyladenine (BA) was used. The conventional medium was gelled with 0.5% plant agar, and wheat starch was used as an alternative gelling agent in a concentration of 5%. The results showed that for all blackberry cultivars, the highest number of shoots/inoculum was obtained in wheat starch-gelled culture medium, with a maximum value of 54.42 ± 4.18 presented by ‘Karaka Black’. Considering the length of the proliferated shoots, all tested cultivars presented outstanding results on the culture medium gelled with 5% wheat starch. The highest values regarding shoots length were observed on the ‘Chester Thornless’ followed by ‘Čačanska Bestrna’, and ‘Loch Ness’ with values of 5.55 ± 0.04 cm, 5.46 ± 0.06 cm, and 5.37 ± 0.09 cm, respectively. The genetic uniformity of the micropropagated shoots in relation to their mother plants was confirmed by sequence-related amplified polymorphism (SRAP) and start codon targeted (SCoT) molecular markers.

In vitro culture has become a dependable approach for the mass production of plant material as the market for innovative plant-derived medicinal approaches has grown significantly. Furthermore, because it permits manipulation of biosynthetic routes to boost the production and accumulation of certain compounds, this technology has enormous potential for the manufacture of natural bioactive chemicals. As a result, the goal of this study was to develop an efficient micropropagation system for biomass production and to investigate the accumulation of bioactive compounds from Vaccinium corymbosum L., Duke and Hortblue Petite cultivars. Two in vitro plant tissue culture systems were used for shoots production: a solid medium (5 g/L Plant agar) and liquid medium (Plantform bioreactor). The culture medium used was Woddy Plant Medium (WPM) supplemented with two growth regulators: 0.5 mg/L and 1 mg/L zeatina (Z) and 5 mg/L N6-(2-Isopentenyl) adenine (2iP). The content of phenolic compounds, carotenoids, and chlorophylls of the in vitro shoot extracts were examined via the HPLC-DAD-MS/MS technique. The results showed that cv. Hortblue Petite produced a higher amount of biomass compared with cv. Duke, on all variants of culture media in both systems (solid and liquid), while the shoots extract of the Duke variety in the liquid culture system (under all concentrations of growth regulators) had the highest content of total phenolic compounds (16,665.61 ± 424.93 μg/g). In the case of the lipophilic compounds analysed (chlorophylls and carotenoids), the solid medium reported the highest values, whereas media supplemented with 0.5 mg/L Z was proved to have the richest total content for both cultivars.

Astragalus exscapus L. subsp. transsilvanicus (Schur) Nyár. (Fabaceae) is a rare plant endemic to the Transylvanian Plateau, represented by 24 identified populations. Limited information on the genetic variation and population structure is available, which obstructs efficient measures for conservation strategy. The present study aimed to analyze the genetic diversity and population structure of eight populations of A. exscapus subsp. transsilvanicus revealed by sequence-related amplified polymorphism (SRAP) markers. A total of 164 bands were amplified, 96.7% of which (159) were polymorphic. Nei’s gene diversity index (He) was estimated to be 0.228 at the population level and 0.272 at the subspecies level. The genetic differentiation among populations (Gst) was 0.165, which indicated a low proportion of total genetic diversity. The analysis of molecular variance (AMOVA) indicated that 17% of the total variation of A. exscapus subsp. transsilvanicus is found among the populations, while 83% was found within the populations. A UPGMA dendrogram, principal coordinate analysis, and the STRUCTURE software grouped the populations into two clusters uncorrelated with the provenience of the 125 individuals, which might be attributed to fragmentation processes, insect pollination, population size, and specific environmental conditions of the habitats.

Salinity is one of the most critical abiotic stresses affecting various physiological, biochemical, and molecular functions of plants. This study aimed to assess the effects of different salt concentrations on in vitro blueberry shoots (‘Bluecrop’, ‘Blueray’, ‘Brigitta Blue’, ‘Duke’, ‘Goldtraube’, ‘Hortblue Petite’, and ‘Patriot’ cultivars) and to understand the mechanisms employed by this species under saline conditions. The Woody Plant Medium (WPM) proliferation medium was supplemented with 10, 50, 100, and 150 mM NaCl to induce salt stress. After ten weeks of in vitro culture under salinity stress, various parameters were evaluated, including the number of shoots obtained/explant, shoot length, fresh weight, dry weight, water content, stress tolerance index (STI), and McKinney index (MKI). Additionally, the behaviour of blueberry cultivars under salt stress was analyzed using electron paramagnetic resonance spectroscopy (EPR). Compared to the control (culture medium without NaCl), all treatments with NaCl reduced shoot length and the number of shoots obtained/explant in all studied blueberry cultivars. ‘Brigitta Blue’ reported the shortest shoots (0.04 ± 0.02 cm) at a concentration of 150 mM NaCl, followed by ‘Blueray’ with 0.05 ± 0.03 cm. Also, the lowest number of shoots/explant was recorded for both cultivars under 150 mM NaCl, namely 0.12 ± 0.07 shoots/explant (‘Brigitta Blue’) and 0.11 ± 0.04 shoots/explant (‘Blueray’). Salt tolerance, as expressed by ITS and MKI, confirmed that ‘Goldtraube’ exhibited higher salt tolerance, with the highest ITS values and the lowest MKI values. Further validation presented ‘Goldtraube’ as the most unresolved spectra of the Mn (II) hyperfine structure under all salt concentrations, therefore ‘Goldtraube’ was the most tolerant to saline stress.