Search Results (7)

Viola ucriana Erben & Raimondo is a rare and endangered taxon, endemic to a limited area on Mount Pizzuta in northwestern Sicily, Italy. Its population is significantly threatened by anthropogenic activities, including fires, overgrazing, and habitat alterations. Temporary immersion systems (TISs) have proven effective for large-scale propagation in various protected species, offering potential for ex situ conservation and population reinforcement of V. ucriana. This study aimed to establish a bioreactor-based micropropagation protocol for shoot multiplication and compare the efficacy of a TIS with that of conventional solid culture medium (SCM). Three different plant growth regulators (PGRs) were also compared: 6-benzylaminopurine (BA), zeatin, and meta-topolin-9-riboside (mTR). The starting material originated from seeds collected from mother plants in their natural environment. The best growth outcomes (in terms of shoot multiplication, shoot length, and relative growth rate) were achieved using THE RITA® TIS, with BA (0.2 mg/L) and mTR (0.5 or 0.8 mg/L) outperforming SCM. Anomalous or hyperhydric shoots were observed with all zeatin treatments (especially with 0.8 mg/L) in both the TIS and SCM, suggesting that this cytokinin is unsuitable for V. ucriana biomass production. The rooting phase was significantly improved by transferring propagules onto rockwool cubes fertilized with Hoagland solution. This approach yielded more robust roots in terms of number and length compared to the conventional agar-based medium supplemented with indole-3-butyric acid (IBA). Flow cytometry analysis confirmed the genetic fidelity of the regenerants from the optimal PGR treatments, showing that all plantlets maintained the diploid ploidy level of their maternal plants. Over 90% of the in vitro derived plantlets were successfully acclimatized to greenhouse conditions. This paper represents the first report of V. ucriana biomass multiplication using a RITA^® bioreactor. The stability of the regenerants, confirmed by nuclei quantification via cytofluorimetry, provides guidance in establishing a true-to-type ex situ population, supporting conservation and future reinforcement efforts. Full article

Fluorinated cytokinins have emerged as promising alternatives to traditional cytokinins in Phalaenopsis plant tissue culture, offering enhanced stability and bioactivity. However, their metabolic fate and impact on endogenous cytokinin profiles remain largely unexplored. This study builds upon previous research to investigate the comparative metabolism of the traditional cytokinin 6-Benzylaminopurine (BA) with the successful alternatives 6-(3-fluorobenzylamino)purine (FmT) and 6-(3-fluorobenzylamino)purine 9-riboside (FmTR). Additionally, this study examines the impact of another crucial factor, the use of ventilated versus closed containers, on metabolic processes. The results revealed the distinct metabolic profiles associated with each treatment, highlighting the complex interplay between exogenous and endogenous cytokinin levels. This study is the first to investigate the effects of these stable, synthetic, and exogenous cytokinins on the naturally occurring cytokinin levels and their metabolites in micropropagated Phalaenopsis. Additionally, we proposed an alternative inactivation pathway involving the conversion of FmTR and BA to pT and pTR. These findings provide valuable insights into the intricate relationship between cytokinin metabolism and plant growth under in vitro conditions. Full article

To improve the efficiency of chromium (Cr) phytoextraction by Leersia hexandra Swartz, the effects of mowing on Cr accumulation in L. hexandra were investigated using hydroponic experiments. Mowing heights (0, 5, and 10 cm), mowing interval (30, 60, 90 and 120 days), and mowing frequencies (1, 2, and 3 times) were optimized. Mowing at 10 cm above roots significantly increased shoot biomass of L. hexandra (32.9 g/pot). The 90 days mowing interval achieved the highest shoot biomass (62.8 g/pot). The shoot biomass with thrice mowing (67.0 g/pot) was higher than those with one and twice mowing, as well as no mowing (CK). The increases in biomass might ascribe to the changes in endogenous hormone balance by mowing. Proper mowing significantly increased contents of Gibberellin 3 (GA3), 6-Benzylaminopurine (6-BA), 6-Kinetin (6-KT), and trans-Zeatin-riboside (TZR) in leaves, and 3-Indolepropionic acid (IPA) in stems, but decreased Jasmonic acid (JA) in the leaves and stems, thereby enhancing the regeneration of plant. The enhancement of plant regeneration resulted in the increases of biomass and Cr accumulation. Compared to CK, the optimal mowing method (10 cm, 90 days, 3 times) increased shoot biomass and Cr accumulation by 91.4% and 36.0%, respectively. These findings suggested that proper mowing had application potential to promote efficiency of Cr phytoextraction by L. hexandra. Full article

Salvia bulleyana is a plant native to the Chinese Yunnan Province. This species has been used in traditional Chinese medicine as a substitute for Danshen (the roots of Salvia miltiorrhiza). The aim of our study was to establish an effective system for propagating S. bulleyana shoots to obtain large amounts of material rich in bioactive compounds. Phytohormones were used to regulate shoot growth and regeneration potential and influence plant secondary metabolism. The shoot tips were incubated on a Murashige and Skoog agar medium supplemented with 0.1 or 0.5 mg/L IAA (indole-3-acetic acid) and the cytokinins benzylaminopurine (BAP), meta-topoline (M-T), 6-benzylaminopurine riboside (RBAP), N-benzyl-9-(2-tetrahydropyranyl)-adenine (BPA) or kinetin, (K) at concentrations of 0.5, 1 or 2 mg/L. It was observed that the type and concentration of growth regulator significantly influenced the regeneration potential of S. bulleyana shoots. The highest multiplication rate was obtained when 0.1 mg/L IAA and 2 mg/L BPA were used. Under these conditions, 100% of shoot tips formed buds and almost seven buds/shoot per explant were obtained after five weeks. Meanwhile, the highest biomass was found for shoots growing on a medium supplemented with 0.1 mg/L IAA and 1 mg/L M-T: 1.2 g of fresh weight and 0.17 g of dry weight. However, a medium with 0.1 mg/L IAA and 2 mg/L RBAP was most favorable for bioactive phenolic acid content, with a total polyphenol level (37.7 mg/g dw) 4.5 times higher than in shoots grown on medium without growth regulators (8.23 mg/g dw). Finally, optimal conditions were selected by TOPSIS (technique for order of preference by similarity to the ideal solution); the culture of S. bulleyana grown on an MS medium containing 0.1 mg/L IAA and 1 mg/L M-T was found to be the most efficient for polyphenol accumulation and can be used for the production of medicinally relevant compounds. Full article

Cyclanilide (CYC), a plant growth regulator, is a potent shoot branching agent in apple. However, its mechanism remains unclear. The current study revealed that CYC treatment resulted in massive reprogramming of the axillary bud transcriptome, implicating several hormones in the response. We observed a marked increase (approximately 2-fold) in the level of zeatin riboside and a significant decrease (approximately 2-fold) in the level of abscisic acid (ABA). Zeatin metabolism gene cytokinin (CTK) oxidase 1 (CKX 1) was down-regulated at 168 h after CYC treatment compared with the control. Weighted gene co-expression network analysis of differentially expressed genes demonstrated the turquoise module clusters exhibited the highest positive correlation with zeatin riboside (r = 0.92) and the highest negative correlation with ABA (r = −0.8). A total of 37 genes were significantly enriched in the plant hormone signal transduction pathway in the turquoise module. Among them, the expressions of CTK receptor genes WOODEN LEG and the CTK type-A response regulators genes ARR3 and ARR9 were up-regulated. ABA signal response genes protein phosphatase 2C genes ABI2 and ABI5 were down-regulated in lateral buds after CYC treatment at 168 h. In addition, exogenous application of 6-benzylaminopurine (6-BA, a synthetic type of CTK) and CYC enhanced the inducing effect of CYC, whereas exogenous application of lovastatin (a synthetic type of inhibitor of CTK biosynthesis) or ABA and CYC weakened the promoting effect of CYC. These results collectively revealed that the stimulation of bud growth by CYC might involve CTK biosynthesis and signalling, including genes CKX1 and ARR3/9, which provided a direction for further study of the branching promoting mechanism of CYC. Full article

The present study demonstrates hormonal control of Salvia viridis growth and development using four different purine-type cytokinins at different concentrations. The addition of cytokinins significantly increased biomass of cultures, proliferation rate, and, interestingly, secondary metabolite production. The best response in terms of multiplication ratio was recorded on Murashige and Skoog medium supplemented with 0.5 mg/L BPA (N-benzylotetrahydropyranyl adenine), while the greatest biomass accumulation was achieved when supplemented with 1 mg/L m-T (meta-topoline). Quantitative UPLC-DAD analysis of the hydromethanolic extract from S. viridis culture revealed the presence of 12 polyphenols: seven phenolic acids and five phenylethanoids. The highest total content of polyphenolic compounds was found in shoots cultivated on medium with 2 mg/L BPA (18.66 mg/g DW): almost twice that of control shoots. The medium was also the most optimal for the biosynthesis of rosmarinic acid, the predominant phenolic acid. However, the greater phenylethanoid accumulation was stimulated by 1 mg/L m-T: the metabolite content was above three times higher than that found in shoots grown on the control medium (8.03 mg/g DW vs. 2.37 mg/g DW). Hence, it was demonstrated that phytohormones are capable of influencing not only vital physiological processes, but therapeutic potential of plants as well. Therefore, the cytokinin-based sage cultures may be also considered as the alternative sources of bioactive compounds. Full article

Yeast cells expressing cDNA libraries have provided two new approaches to facilitate further identification of cytokinin-binding proteins and receptors. These are the yeast three hybrid (Y3H) system and fluorescence activated cell sorting (FACS). The Y3H system requires a synthetic hybrid ligand comprising an “anchor” moiety (e.g., dexamethasone) linked to a cytokinin via a spacer. In the yeast nucleus, this ligand by binding connects two fusion proteins leading to a reporter gene activation and detection and characterisation of cytokinin binding proteins. Herein is reported the first synthesis of dexamethasone-cytokinin ligands with a spacer linkage. This was attached to the purine ring of 6-benzylaminopurine (BAP) at positions 2, 8 or 9. To achieve this, dexamethasone was modified by periodate oxidation yielding a carboxylic group used for conjugation to the spacer by amide formation. Biotinyl derivatives of cytokinins for FACS included those synthesised by reaction of an activated ester of biotin with 8-(10-amino-decylamino) derivatives of BAP and BAP 9-riboside. Properties of the conjugates and some biological situations where they could be applicable are discussed briefly. Full article