Search Results (24)

Human skin fibroblasts are an excellent in vitro model for tracking the processes occurring in human skin and studying the potential impact of various biologically active substances on these processes. Two plant hormones, which are included in the cytokinins group—kinetin (K) and N-6-benzyladenine (BA)—have a positive effect on human skin. Therefore, an attempt was made to examine the effect they have on key skin functions, cell proliferation, and migration, as well as collagen synthesis in them. The effect of phytohormones was studied at selected concentrations for kinetin—10 μM and 1 μM—and for N-6-benzyladenine—1 μM and 0.1 μM. A wound-healing assay was used in order to analyze cell migration and proliferation. The content of total protein and collagen in cells and culture medium was determined. The obtained results confirm that the studied compounds induce cell migration and proliferation, as well as collagen biosynthesis. The positive effect of kinetin and N-6-benzyladenine on fibroblast metabolism that we have demonstrated allows us to indicate them as compounds with potentially therapeutic properties. Therefore, we conclude that they should be subjected to further molecular and in vivo studies focusing on pathologies connected with skin diseases and aging. Full article

Cryopreservation is a promising method for the long-term preservation of plant germplasm, especially for vegetatively propagated species like freesias. In this study, we investigate streamlining the cryopreservation process for ‘Sunny Gold’ Freesia, starting from effective in vitro initiation and proliferation using various plant growth regulator combinations. We also assess the impact of subculture on regrowth rates after cryopreservation. The shoot tips were successfully initiated in vitro after sterilization. The shoots were multiplied an average of three times in media containing N6-benzyladenine and kinetin. The regrowth rates of non-cryopreserved shoot tips excised from different subculture cycles did not differ significantly, with rates of 44% observed for plants from more than five subcultures and 47% for those from three subcultures. However, only the shoot tips excised from cultures subjected to three subculture cycles were able to recover after cryopreservation, with a regrowth rate of 31%. Our findings lay the groundwork for the development of an efficient cryopreservation protocol for freesias in the future. Full article

A new quinazolinone alkaloid named peniquinazolinone A (1), as well as eleven known compounds, 2-(2-hydroxy-3-phenylpropionamido)-N-methylbenzamide (2), viridicatin (3), viridicatol (4), (±)-cyclopeptin (5a/5b), dehydrocyclopeptin (6), cyclopenin (7), cyclopenol (8), methyl-indole-3-carboxylate (9), 2,5-dihydroxyphenyl acetate (10), methyl m-hydroxyphenylacetate (11), and conidiogenone B (12), were isolated from the endophytic Penicillium sp. HJT-A-6. The chemical structures of all the compounds were elucidated by comprehensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS. The absolute configuration at C-13 of peniquinazolinone A (1) was established by applying the modified Mosher’s method. Compounds 2, 3, and 7 exhibited an optimal promoting effect on the seed germination of Rhodiola tibetica at a concentration of 0.01 mg/mL, while the optimal concentration for compounds 4 and 9 to promote Rhodiola tibetica seed germination was 0.001 mg/mL. Compound 12 showed optimal seed-germination-promoting activity at a concentration of 0.1 mg/mL. Compared with the positive drug 6-benzyladenine (6-BA), compounds 2, 3, 4, 7, 9, and 12 could extend the seed germination period of Rhodiola tibetica up to the 11th day. Full article

This study evaluated the effects of N⁶-benzyladenine (BAP) seed preconditioning and seedling-derived explants on in vitro plant regeneration potential in soybeans (Glycine max [L.] Merrill.). The findings showed that seed preconditioning with 2.55 mg/L BAP prior to germination significantly influenced seedling establishment and the development of shoots, shoot elongation, and rooting on MS media supplemented with BAP and TDZ, compared to the negative (MS-NC) and positive (MS-NP) controls. The results also showed significant differences based on the genotypes, with Dundee recording 91.0% germination over a minimum of 5 days, compared to 74.2% with Peking, followed by 87.5% and 80.0% overall shoot induction frequency in these genotypes, respectively. Regenerated shoots were successfully elongated on MS medium supplemented with 0.5 mg/L BAP plus 0.6 mg/L GA₃ and rooted on hormone-free medium, for 3‒4 weeks, and then hardened in the acclimatization growth room under elevated light levels. Overall, this study revealed that BAP preconditioning of seeds enhances the frequency of bud initiation and shoot proliferation, mostly in whole-seedling and cotyledonary node explants subcultured on MS-E and MS-A media supplemented with BAP in combination with TDZ. Full article

Pinus peuce (Macedonian pine) is considered a valuable ornamental tree that is frequently planted in parks and gardens, especially in Western Europe. This endemic pine is one of the most valuable conifer species in its native range, which currently consists of only two disjunct populations restricted to small mountainous areas of the Balkans and is listed as a near-threatened species. The reproduction of Macedonian pine by seed is limited, so in vitro propagation methods have emerged as a promising tool for large-scale propagation. The objective of this study was to develop an improved system for the micropropagation of P. peuce from juvenile plant material using a short-term liquid cytokinin pulse. For that, explants derived from 4-week-old seedlings were pulse-treated with different concentrations of N⁶-benzyladenine (BA) for 1 or 2 h to stimulate the induction of axillary buds. The highest axillary shoot formation was achieved with 222 µM BA pulse treatment, with an average number of ~six shoots per explant. Elongated shoots (≥10 mm) were detached from the explants and pulse-treated with 0.27 or 1.08 mM α-naphthaleneacetic acid (NAA) or 0.25 or 0.98 mM indole-3-butyric acid (IBA) for 1 or 2 h. IBA was more effective than NAA and led to a maximum rooting percentage (up to 40%) and the highest number of acclimatized plants (15–20%). Rooted plants were successfully transferred to ex vitro conditions. Full article

Helianthus verticillatus (Asteraceae), a whorled sunflower, is a perennial species restricted to a few locations in the southeastern United States and is now considered endangered. Therefore, restoring and protecting H. verticillatus as a species is a priority. This study introduces a highly efficient in vitro adventitious plant regeneration system from leaf explants, utilizing five diverse specimens of H. verticillatus, each representing distinct genotypes with phenotypic variations in leaf and stem morphology. Key factors influencing in vitro morphogenesis, including genetic constitution, explant source, and plant growth regulators (PGRs), were identified. The study revealed a remarkably strong genotype-dependent impact on the regeneration efficiency of the investigated H. verticillatus genotypes, ranging from a lack of regeneration to highly effective regeneration. The selection of two genotypes with varying regeneration abilities provides valuable models for genetic analyses, offering insights into factors influencing the regeneration potential of this endangered species. Optimum adventitious shoot regeneration results were achieved using Murashige and Skoog basal media (MS) supplemented with 8.8 µM N6-benzyladenine (BA) and 1.08 µM α-naphthalene acetic acid (NAA). This combination yielded the highest adventitious shoot production. Subsequent successful rooting on ½ MS medium without PGRs further solidified the efficiency of the developed protocol. Regenerated plantlets, demonstrating robust shoots and roots, were successfully acclimatized to greenhouse conditions with a 95% survival rate. The protocol developed in this study is the first such report for this endangered species and is expected to contribute to future genetic manipulation and modification studies. Full article

Black Knot (BK) is a deadly disease of European (Prunus domestics) and Japanese (Prunus salicina) plums caused by the hemibiotrophic fungus Apiosporina morbosa. After infection, the appearance of warty black knots indicates a phytohormonal imbalance in infected tissues. Based on this hypothesis, we quantified phytohormones such as indole-3-acetic acid, tryptophan, indoleamines (N-acetylserotonin, serotonin, and melatonin), and cytokinins (zeatin, 6-benzyladenine, and 2-isopentenyladenine) in temporally collected tissues of susceptible and resistant genotypes belonging to European and Japanese plums during of BK progression. The results suggested auxin-cytokinins interplay driven by A. morbosa appears to be vital in disease progression by hampering the plant defense system. Taken together, our results indicate the possibility of using the phytohormone profile as a biomarker for BK resistance in plums. Full article

A promising carrier for the development of polymer systems with controlled release of biologically active compounds is the aminopolysaccharide chitosan. In the present work, we studied the possibility of using chitosan films as a matrix for the N⁶-benzyladenine (BA), which is the natural cytokinin widely used in tissue culture. The aim of this work was to develop biopolymer carriers containing phytohormones cytokinins that provide its controlled release. As a result of the work, a number of biopolymer carriers containing BA were obtained, and the kinetics of moisture absorption of the resulting complexes and the kinetics of their release of cytokinins were studied. It has been shown that the use of a polymer carrier based on chitosan is a convenient matrix for achieving a prolonged biological effect from cytokinins. The obtained results will make it possible to purposefully design materials with an optimal delivery rate of cytokinins for a biological object. Full article

Anthyllis hermanniae L. (Fabaceae) is a perennial Mediterranean shrub with the potential to be used as a bee-friendly ornamental plant in arid and semi-arid regions, valued for its tolerance of barren soils, winds, and strong temperature changes. With the aim of facilitating the introduction of the species into the horticulture industry, its in vitro seed and clonal propagation was investigated for the first time, to our knowledge. Seeds stored in the dark at room temperature for 4, 7, 9, 12, and 18 months germinated at percentages higher than 80% after scarification, when incubated in vitro in solid half-strength Murashige and Skoog (MS) medium at temperatures from 10 to 25 °C, while photoperiod (continuous darkness or 16 h light period/8 h dark) during incubation did not affect germination. Explants excised from in vitro grown seedlings established at higher percentages compared to explants from adult native plants, more efficiently in MS medium with 1.0 mg L⁻¹ 6 N benzyladenine (BA). During subcultures in the same medium, juvenile explants formed more and longer shoots than adult ones. Almost all adult explants formed shoots when subcultured in MS medium with 0.0 to 4.0 mg L⁻¹ BA, zeatin, kinetin or 6-(γ,γ-dimethylallylamino)purine (2iP). ΒA at 0.5 to 2.0 mg L⁻¹ induced many more shoots (17–21) per explant and much higher multiplication indices compared to all other cytokinins, while longer shoots were produced in a medium without hormones or with 0.5–1.0 mg L⁻¹ 2iP. Microshoots cultured in half-strength MS medium with 0.0–4.0 mg L⁻¹ indole-3-butyric acid rooted at highest percentage (around 70%) in the medium containing 4.0 mg L⁻¹ IBA, while microshoots of juvenile origin developed more and longer roots compared to adult ones. Micropropagated plantlets were successfully acclimatized ex vitro (>97%), regardless of their origin. The efficient micropropagation of A. hermaniae will facilitate its sustainable exploitation as a bee-friendly landscape plant, a forage plant for honeybees in Mediterranean areas, and a medicinal plant. Full article

Members of the genus Sorbus are the only endemic tree species that occur in Czechia. They are important components of endangered plant communities. Their natural regeneration is usually problematic because of their mode of reproduction and because they can survive in rare populations with small numbers of individuals. The aim of this study was to develop a successful micropropagation protocol for selected Sorbus species, of which two are endemic (S. gemella and S. omissa) and two are hybrid (S. × abscondita and S. × kitaibeliana). We found significant differences in shoot induction and rooting ability between the Sorbus species under study. With the exception of S. × abscondita, N⁶-benzyladenine had a significantly greater effect on shoot regeneration, both in terms of shoot number and total shoot length, than meta-topolin. Root induction was key to the successful micropropagation of the Sorbus species studied. Our results show that four Sorbus species can be successfully rooted under ex vitro conditions, without a rooting powder treatment in a steamed peat-perlite substrate. Auxin-untreated microcuttings of S. gemella, S. × kitaibeliana and S. omissa, but not S. × abscondita, rooted better than ones treated with indole-3-butyric acid. This is the first time a micropropagation protocol for S. omissa, S. × abscondita and S. × kitaibeliana has been published. Full article

In the past, chemical thinning dominated in fruit orchards. This paper for the special issue outlines alternatives to chemical thinning for crop load management (CLM) and its effect on fruit size, firmness, sugar, starch, and weight, indicating ripeness and fruit quality, yield, and alternate bearing. A total of 450 apple trees (Malus domestica Borkh., cv. ‘Roter Boskoop’; six years old) on M9 rootstock were used at the Klein-Altendorf experimental station (50° N) of the University of Bonn, Germany. As the first alternatives, trees were mechanically blossom-thinned at the balloon stage (BBCH 59) with a rotor speed of 320 rpm or 380 rpm at 5 km/h tractor speed or were chemically thinned at the full bloom stage (BBCH 65) with ammonium thiosulfate (ATS), ethephon (ETH), and/or 6-benzyladenine (BA) at 10–12 mm fruit size (BBCH 71) after applying ATS/ETH. Flower clusters and/or cluster leaves (source) were manually removed to determine the optimum sink-source ratio to achieve different ratios of fruitlets (sink) relative to the leaves (source) at fruit set (BBCH 67–69). Un-thinned, adjacent trees served as the control. The majority of CLM methods improved fruit size and weight. Removing cluster leaves at fruit set increased fruit size and weight of the remaining fruit, which has not been observed before. The most effective treatment for fruit size and weight and return bloom was the 75% flower cluster and complete cluster leaf removal. Removal of more than 50% of flower clusters successfully improved return bloom, indicative of alternate bearing. The mechanical blossom thinning had a positive effect on fruit size and weight with a return bloom similar to that of removal of 50% flower clusters. Full article

Shoot cultures of hypericin non-producing H. calycinum L. (primitive Ascyreia section), hypericin-producing H. perforatum L., H. tetrapterum Fries (section Hypericum) and H. richeri Vill. (the evolutionarily most advanced section Drosocarpium in our study) were developed and investigated for their growth, development, hypericin content and endogenous phytohormone levels. Hypericins in wild-growing H. richeri significantly exceeded those in H. perforatum and H. tetrapterum. H. richeri also had the highest hypericin productivity in vitro in medium supplemented with 0.2 mg/L N⁶-benzyladenine and 0.1 mg/L indole-3-butyric acid and H. tetrapterum—the lowest one in all media modifications. In shoot culture conditions, the evolutionarily oldest H. calycinum had the highest content of salicylic acid and total jasmonates in some of its treatments, as well as dominance of the storage form of abscisic acid (ABA-glucose ester) and lowest cytokinin ribosides and cytokinin O-glucosides as compared with the other three species. In addition, the evolutionarily youngest H. richeri was characterized by the highest total amount of cytokinin ribosides. Thus, both evolutionary development and the hypericin production capacity seemed to interact closely with the physiological parameters of the plant organism, such as endogenous phytohormones, leading to the possible hypothesis that hypericin productivity may have arisen in the evolution of Hypericum as a means to adapt to environmental changes. Full article

Cytokinins, classical phytohormones, affect all stages of plant ontogenesis, but their application in agriculture is limited because of the lack of appropriate ligands, including those specific for individual cytokinin receptors. In this work, a series of chiral N⁶-benzyladenine derivatives were studied as potential cytokinins or anticytokinins. All compounds contained a methyl group at the α-carbon atom of the benzyl moiety, making them R- or S-enantiomers. Four pairs of chiral nucleobases and corresponding ribonucleosides containing various substituents at the C2 position of adenine heterocycle were synthesized. A nucleophilic substitution reaction by secondary optically active amines was used. A strong influence of the chirality of studied compounds on their interaction with individual cytokinin receptors of Arabidopsis thaliana was uncovered in in vivo and in vitro assays. The AHK2 and CRE1/AHK4 receptors were shown to have low affinity for the studied S-nucleobases while the AHK3 receptor exhibited significant affinity for most of them. Thereby, three synthetic AHK3-specific cytokinins were discovered: N⁶-((S)-α-methylbenzyl)adenine (S-MBA), 2-fluoro,N⁶-((S)-α-methylbenzyl)adenine (S-FMBA) and 2-chloro,N⁶-((S)-α-methylbenzyl)adenine (S-CMBA). Interaction patterns between individual receptors and specific enantiomers were rationalized by structure analysis and molecular docking. Two other S-enantiomers (N⁶-((S)-α-methylbenzyl)adenosine, 2-amino,N⁶-((S)-α-methylbenzyl)adenosine) were found to exhibit receptor-specific and chirality-dependent anticytokinin properties. Full article

Phalaenopsis is an orchid genus of great economic value in world floriculture. In vitro clonal propagation is the only large-scale feasible method for Phalaenopsis propagation, but it is difficult because of the low multiplication rate. The aim of this study was to evaluate the effect of types and concentrations of N⁶-benzyladenine (6-BA) and gibberellic acid (GA₃) on the in vitro multiplication of shoots from inflorescence nodal segments (INS) of Phalaenopsis hybrids. INS with one axillary bud were inoculated in New Dogashima Medium with different combinations of BA and GA₃. The results show that the treatment containing 1.0 mg L⁻¹ BA and 1.5 mg L⁻¹ GA₃ showed the higher percentage of live inflorescence segments (71.48%) and a number of shoots (1.68 shoots/INS). The highest 6-BA concentration (4 mg L⁻¹) tested in this study resulted in the best shoot multiplication rate (4.3). Contamination and browning of the INS tissues were the main difficulties identified for clonal propagation of Phalaenopsis. Successful in vitro rooting occurred on half-strength Murashige and Skoog medium (100%), and acclimatization (100%) was obtained independent of the substrates. However, the best gains in number of roots, leaves, chlorophyll content, and fresh weight of plantlets were achieved using vermiculite. Full article

In the coming years, the application of biostimulants will become a fundamental tool for reducing chemical fertilization in agriculture, increasing the efficiency of soils and crops to face up to climate change conditions. Following this context, we have assessed the effect of garden waste compost tea (CT) in a ratio of 1: 5 (v/v) with water on root morphology of tomato var. Tres Cantos. The studied CT showed relevant content of K₂O, N, humic acids and, to a lesser extent, amino acids. Three treatments were proposed: water, optimal tomato Hoagland solution and CT, which were axenically prepared. Tomato seeds were sterilized, germinated and then transferred to the considered treatments. Then, root growth parameters were measured and it was observed that CT promoted primary root length, as well as the number of lateral roots. Moreover, indolacetic acid, indol-3-butyric acid, zeatine, 6-benzyladenine and gibberellic acid concentrations were determined, but they were not detected in any case. Thus, other direct or indirect pathways seem to be involved in CT-mediated tomato root modulation. Full article