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Background: Kale, a versatile cruciferous crop, valued for its pro-health benefits, stress resistance, and potential applications in forage and cosmetics, holds promise for further enhancement of its bioactive compounds through in vitro cultivation methods. Micropropagation techniques use cytokinins (CKs) which are characterized by various proliferative efficiency. Despite the extensive knowledge regarding CKs, there remains a gap in understanding their role in the physiological mechanisms. That is why, here we investigated the effects of three CKs - kinetin (Kin), 6-benzylaminopurine (BAP), and 2-isopentenyladenine (2iP) - on kale physiology, antioxidant status, steroidal metabolism, and membrane integrity under in vitro cultivation., Results: Our study revealed that while BAP and 2iP stimulated shoot proliferation, they concurrently diminished pigment levels and photosynthetic efficiency. Heightened metabolic activity in response to all CKs was reflected by increased respiratory rate. Despite the differential burst of ROS, the antioxidant properties of kale were associated with the upregulation of guaiacol peroxidase and the scavenging properties of ascorbate rather than glutathione. Notably, CKs fostered the synthesis of sterols, particularly sitosterol, pivotal for cell proliferation and structure of membranes which are strongly disrupted under the action of BAP and 2iP possibly via pathway related to phospholipase D and lipoxygenase which were upregulated. Intriguingly, both CKs treatment spurred the accumulation of sitostenone, known for its ROS scavenging and therapeutic potential. The differential effects of CKs on brassicasterol levels and brassinosteroid (BRs) receptor suggest potential interactions between CKs and BRs., Conclusion: Based on the presented results we conclude that the effect evoked by BAP and 2iP in vitro can improve the industrial significance of kale because this treatment makes possible to control proliferation and/or biosynthesis routes of valuable beneficial compounds. Our work offers significant insights into the nuanced effects of CKs on kale physiology and metabolism, illuminating potential avenues for their application in plant biotechnology and medicinal research., (© 2024. The Author(s).)

Purpose: Juniper ( Juniperus procera ) is a common forest tree species in Saudi Arabia. The decline in many populations of J . procera in Saudi Arabia is mainly due to seed dormancy and loss of natural regeneration. This study assessed the effects of chemical and hormonal treatments on seed germination and seedling growth in juniper plants., Methods: The seeds were subjected to either chemical scarification with 90% sulfuric acid and 20% acetic acid for 6 min or hormonal treatment by seed soaking in two concentrations (50 and 100 ppm) of three growth regulators, namely, indole acetic acid (IAA), gibberellins (GA 3 ), and kinetin, for 72 h. A control group without any seed treatment was also prepared. The experiments were performed in an incubator maintained at room temperature and under a light and dark period of 12 h for 6 w. The germinated seeds for each treatment were counted and removed from the dishes. The selected germinated seeds from different treatments were planted in a greenhouse and irrigated with tap water for another 6 weeks. The hormone-treated seedlings were sprayed with their corresponding hormone concentrations 1 w after planting., Results: The highest percentage of seed germination was significantly recorded after seed soaking in 50 ppm GA 3 , whereas treatment with IAA (100 ppm) resulted in the best seedling growth. Seedlings treated with the three phytohormones showed a significant increase in photosynthetic pigments, total soluble sugars, proteins, percentage of oil, IAA, GA 3 , and kinetin contents of juniper seedlings compared with the control value, whereas abscisic acid content was decreased compared with chemical treatments., Conclusion: The investigated different treatments had an effective role in breaking seed dormancy and improving seedling growth of J . procera , which is facing a notable decline in its population worldwide. Moreover, such an effect was more pronounced in the three phytohormones that succeeded in breaking dormancy and growth of the Juniperus plant than in the other treatments., Competing Interests: The authors declare there are no competing interests., (©2024 Jabbour and Alzahrani.)

Key Message: Increase of ENHANCER OF SHOOT REGENERATION 2 expression was consistent to treatment with kinetin, TIS108, and KK094 in adventitious shoot formation of ipecac. Unlike many plant species, ipecac (Carapichea ipecacuanha (Brot.) L. Andersson) can form adventitious shoots in tissue culture without cytokinin (CK) treatment. Strigolactone (SL) biosynthesis and signaling inhibitors stimulate adventitious shoot formation in ipecac, suggesting their potential use as novel growth regulators in plant tissue culture, but the molecular mechanism of their action is unclear. In this study, we compared the effects of SL-related inhibitors (TIS108 and KK094) and CKs (2iP, tZ, and kinetin) on adventitious shoot formation in ipecac. Exogenously applied SL-related inhibitors and CKs stimulated adventitious shoot formation. Combinations of SL-related inhibitors and kinetin also promoted adventitious shoot formation, but without additive effects. We also analyzed the expression of CK biosynthesis genes in ipecac. TIS108 increased the expression of the ipecac homolog of ISOPENTENYL TRANSFERASE 3 (CiIPT3) but decreased that of LONELY GUY 7 homolog (CiLOG7), presumably resulting in no change in 2iP-type CK levels. KK094 and kinetin increased CiLOG7 expression, elevating 2iP-type CK levels. Among pluripotency- and meristem-related genes, TIS108, KK094, and kinetin consistently increased the expression of ENHANCER OF SHOOT REGENERATION 2 homolog (CiESR2), which has a key role in shoot regeneration, in the internodal segment region that formed adventitious shoots. We propose that CiESR2 might be a key stimulator of adventitious shoot formation in ipecac., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Kinetin riboside is a naturally produced cytokinin that displays strong antiproliferative activity in various human cancer cells. However, the mechanism of chemoprevention in colorectal cancer cells has not been elucidated. We used a cell-based reporter system to identify kinetin riboside as an antagonist of the Wnt/β-catenin pathway, which is aberrantly upregulated in colorectal cancer. Kinetin riboside suppressed β-catenin response transcription (CRT) by accelerating the degradation of intracellular β-catenin via a proteasomal degradation pathway. Pharmacological inhibition of glycogen synthase kinase-3β did not affect CRT downregulation. Kinetin riboside decreased the intracellular β-catenin levels in colorectal cancer cells with mutations in adenomatous polyposis coli (APC) and β-catenin. Consistently, kinetin riboside repressed expression of c-Myc and cyclin D1, β-catenin/T-cell factor (TCF)-dependent genes, and inhibited the proliferation of colorectal cancer cells. In addition, kinetin riboside stimulated apoptosis, as measured by an increase in annexin V-FITC-stained cells. These findings suggest that kinetin riboside exerts its anti-cancer activity by promoting β-catenin degradation and has significant potential as a chemopreventive agent for colorectal cancer cells.

Hepatic fibrosis is the pathological repair response of the liver to chronic injury; hepatic stellate cell (HSC) activation is the central link in the pathogenesis of hepatic fibrosis. Previously, we showed that kinetin, a plant cytokinin hormone, has a protective effect on CCl 4 -induced liver injury in mice. However, the role of kinetin in liver fibrosis remains unclear. We aimed to study these protective effects and to determine the mechanisms by which kinetin mediates HSC activation and apoptosis. For this purpose, the human HSC line LX-2 was treated with 10 ng/ml transforming growth factor-β1 (TGF-β1) for 24 h to stimulate activation. We found that treatment with kinetin at the sub-cytotoxic dose of 40 μg/ml for 48 h reduced the expression of the HSC activation marker α-SMA and inhibited the secretion of extracellular matrix proteins. In addition, kinetin was found to inhibit the proliferation and migration of LX-2 cells. We found that kinetin induced apoptosis in LX-2 cells by increasing the level of cleaved-caspase 3 and the Bax-to-Bcl-2 ratio. Interestingly, these effect were not observed in quiescent HSCs, suggesting that they are activation-dependent. Further study showed that kinetin attenuates activation and promotes apoptosis of LX-2 cells in vitro in part by suppressing the TGF-β1/Smad signaling pathway., Competing Interests: Declaration of Competing Interest Fuchang Jin, Ming-hui Zhou, Jingjing Chen, Yi Lin, Qiwei Zhang,Qiuxian Xu,Changchun and Zhang,Zhen-gang Zhang declare that they have no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The development and utilization of coastal saline-alkali lands hold significant importance in mitigating the shortage of cultivated land resources in China, enhancing the agro-ecological environment in coastal saline and alkaline areas, and ensuring national food security. We set up both pot and field trials (randomized block design) at Xinxiang experimental station of Institute of Crop Science, Chinese Academy of Agricultural Sciences (ICS-CAAS) and Dongying Yellow River Delta Modern Agricultural Research Base in Shandong Province in 2021 and 2022, respectively. The experimental materials, Jiliang 1 and Jiliang 2, underwent seed dressing with GKI composites at concentrations of 2.5 and 5 mL·kg -1 . These composites, which contained the main components of gibberellin, kinetin, and indole butyric acid, were denoted as GKI2.5 and GKI5.0, respectively. The control plots (CK) received water seed dressing. The aim was to assess the regulatory effects of GKI on salt tolerance and grain sorghum yield. Compared to CK, the GKI2.5 and GKI5.0 seed dressing treatments significantly enhanced the growth and development of the two grain sorghum varieties, increased antioxidant enzyme activity and soluble protein content of sorghum leaves, while reducing leaf malondialdehyde content. Moreover, the GKI treatments increased leaf net photosynthetic rate. Under field conditions, yields of Jiliang 1 and Jiliang 2 were enhanced by an average of 17.1% and 19.1%, respectively. In conclusion, GKI seed dressing treatment effectively promoted the growth and development of sorghum under salt stress. It enhanced the antioxidant and osmoregulatory capacities of leaves, reduced the level of membrane lipid peroxidation, and improved net photosynthetic rate of leaves, which together improved the salt tolerance and sorghum yield.

Background: Water deficit is one of the most significant abiotic factors affecting rice and agricultural production worldwide. In hybrid rice, cytoplasmic male sterility (CMS) is an important technique for creating high-yielding crop based on heterosis. The phytohormone kinetin (Kin) regulates cell division in plant during the early stages of grain formation, as well as flow assimilation and osmotic regulation under water stress. The present study performed to estimate the effects of irrigation intervals (irrigation each six days (I 6 ), nine days (I 9 ), twelve days (I 12 ) and fifteen days (I 15 ) against continuous flooding (CF, each three days)) and kinetin exogenously application (control, 15 mg L -1 and 30 mg L -1 ) on hybrid rice (L1, IR69625A; L2, G46A and R, Giza 178 R) seed production., Results: Leaves traits (Chlorophyll content (CHC), relative water content (RWC), stomatal conductance (SC), Leaf temperature (LT) and transpiration rate (TR)), floral traits such as style length (SL) and total stigma length (TSL), in addition to root traits (i.e., root length (RL), root volume (RV), root: shoot ratio (RSR), root thickness (RT), root xylem vessels number (RXVN) and root xylem vessel area (RXVA) were evaluated and a significant enhancement in most traits was observed. Applying 30 mg L -1 kinetin significantly and positively enhanced all growth, floral and roots traits (RV and RXVA recorded the most increased values by 14.8% and 23.9%, respectively) under prolonging irrigation intervals, in comparison to non-treated plants., Conclusions: Subsequently, spraying kinetin exogenously on foliar could be an alternative method to reduce the harmful influences of water deficiency during seed production in hybrid rice., (© 2023. BioMed Central Ltd., part of Springer Nature.)

In pioneering research, it has been documented that the CNT influences the development of plants through the balance of phytoregulators. Therefore, in this work the objective is to evaluate the effects of the CNT functionalized by non-covalent method with kinetin that have in Avena sativa. CNT was characterized by FTIR and Raman to confirm functionality. The results showed that the application of CNT with phytoregulators modified plant development., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Microscopy Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Studies of vitality/mortality of cortex cells, as well as of the concentrations of ethylene (ETH), gibberellins (GAs), indolic compounds/auxins (ICs/AUXs) and cytokinins (CKs), were undertaken to explain the hormonal background of kinetin (Kin)-regulated cell death (RCD), which is induced in the cortex of the apical parts of roots of faba bean (Vicia faba ssp. minor) seedlings. Quantification was carried out with fluorescence microscopy, ETH sensors, spectrophotometry and ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC‒MS/MS). The results indicated that Kin was metabolized to the transport form, i.e., kinetin-9-glucoside (Kin9G) and kinetin riboside (KinR). KinR was then converted to cis-zeatin (cZ) in apical parts of roots with meristems, to cis-zeatin riboside (cZR) in apical parts of roots without meristems and finally to cis-zeatin riboside 5'-monophosphate (cZR5'MP), which is indicated to be a ligand of cytokinin-dependent receptors inducing CD. The process may be enhanced by an increase in the amount of dihydrozeatin riboside (DHZR) as a byproduct of the pathway of zeatin metabolism. It seems that crosstalk of ETH, ICs/AUXs, GAs and CKs with the cZR5'MP, the cis-zeatin-dependent pathway, but not the trans-zeatin-dependent pathway, is responsible for Kin-RCD, indicating that the process is very specific and offers a useful model for studies of CD hallmarks in plants., (© 2023. The Author(s).)

Plants are sessile and mostly exposed to various environmental stresses which hamper plant growth, development, and significantly decline its production. Drought stress is considered to be one of the most significant limiting factors for crop plants, notably in arid and semi-arid parts the world. Therefore, the present study aimed to evaluate the potential impact of different concentrations (10, 100, and 200 µg/mL) of kinetin capped zinc oxide nanoparticles (Kn-ZnONPs) on Vigna radiata (L.) R. Wilczek under varying levels (5%, 10%, 15%) of PEG-induced drought stress. ZnONPs were synthesized by a co-precipitation method using Zinc acetate as a precursor at pH-12, incinerated to 500 °C, and kinetin was used as a surface functionalizing agent. The resulting Kn-ZnONPs were characterized by various contemporary analytical techniques, including SEM, SEM-EDS, XRD, DLS, and Zeta potential and IR spectroscopy. Crystalline Kn-ZnONPs, with a zeta potential of 27.8 mV and a size of 67.78 nm, of hexagonal wurtzite structure and vibrational stretches associated with N-H, C-O, C-N, etc., were confirmed. PEG-induced drought stress significantly reduced the growth of V. radiata by declining the chlorophyll and carotenoid contents. Moreover, a significant decrease in the levels of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), soluble sugar contents, proline, protein contents, phenol, and tannin were observed compared to the control. However, the exogenous application of Kn-ZnONPs ameliorated all photosynthetic parameters by up-regulating the antioxidant defense system through the promotion of SOD, POD, CAT, and lipid peroxidation levels. The biochemical parameters, such as proteins, soluble sugars, and proline, were observed to be maximum in plants treated with 200 µg/mL Kn-ZnONPs under 5% drought stress. The application of Kn-ZnONPs also enhanced the total phenol contents, flavonoid, and tannin contents. In conclusion, the findings of this study demonstrate that the exogenous application of Kn-ZnONPs provides beneficial effects to V. radiata by attenuating the damaging effects of drought stress through the up-regulation of the antioxidant defense system and osmolytes. These results suggest that Kn-ZnONPs have potential as a novel approach to improve crop productivity under drought stress conditions.

Plant cells can undergo regulated cell death in response to exogenous factors (often in a stress context), but also as regular element of development (often regulated by phytohormones). The cellular aspects of these death responses differ, which implies that the early signalling must be different. We use cytokinin-induced programmed cell death as paradigm to get insight into the role of the cytoskeleton for the regulation of developmentally induced cell death, using tobacco BY-2 cells as experimental model. We show that this PCD in response to kinetin correlates with an arrest of the cell cycle, a deregulation of DNA replication, a loss of plasma membrane integrity, a subsequent permeabilisation of the nuclear envelope, an increase of cytosolic calcium correlated with calcium depletion in the culture medium, an increase of callose deposition and the loss of microtubule and actin integrity. We discuss these findings in the context of a working model, where kinetin, mediated by calcium, causes the breakdown of the cytoskeleton, which, either by release of executing proteins or by mitotic catastrophe, will result in PCD., (© 2022. The Author(s).)

Background: In medicinal plants, selection, reproduction and preservation of important genotypes are very necessary. Nowadays, using tissue culture and regeneration techniques of medicinal plants under in vitro conditions has been able to proliferate medicinal plants widely, which is much higher than traditional methods of vegetative propagation. Maca (Lepidium meyenii), is an industrial plant whose root is the usable part. Maca has valuable medicinal effects such as sexual enhancement and reproductive power, infertility treatment, improved sperm count and quality, anti-stress, osteoporosis prevention and more., Methods and Results: This study was conducted to induce callus and regeneration of Maca. First, MS medium supplemented with different concentrations of Kinetin, Naphthaleneacetic acid and 2,4-Dichlorophenoxyacetic acid [0.5, 1 and 2 µM respectively] and control were compared for callus induction from root and leaves. After 38 days of incubation, the first callus appeared, after 50 days of callus induction and after 79 days regeneration occurred. The callus induction experiment was performed for the study of the effect of three explants (leaf, stem and root) and seven hormone levels. The regeneration experiment was carried out by studying the effect of three explants (leaf, stem and root) on eight levels of the hormone. The results of data analysis on callus induction showed that the effects of explants, hormones and their interactions on callus induction percentage were highly significant but not significant on callus growth rate. The results of regression analysis showed that explants, hormones and their interactions had no significant effect on regeneration percentage., Conclusion: Based on our results, the best medium for inducing callus was Hormone 2,4-D [2 µM] and Kinetin [0.5 µM], in which the highest percentage of callus induction was in leaf explants (62%). And the lowest were in stem (30%) and root (27%) explants. According to the comparison of the mean, the best environment for regeneration of the environment was 4 µM 6-Benzylaminopurine 2.5 + Thidiazuron, in which the highest percentage of regeneration was in leaf explant (87%) and stem (69%) and the lowest in root explant (12). %)., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Heat stress caused by rapidly changing climate warming has become a serious threat to crop growth worldwide. Exogenous cytokinin (CK) kinetin (KT) has been shown to have positive effects in improving salt and drought tolerance in plants. However, the mechanism of KT in heat tolerance in rice is poorly understood. Here, we found that exogenously adequate application of KT improved the heat stress tolerance of rice seedlings, with the best effect observed when the application concentration was 10 -9 M. In addition, exogenous application of 10 -9 M KT promoted the expression of CK-responsive OsRR genes, reduced membrane damage and reactive oxygen species (ROS) accumulation in rice, and increased the activity of antioxidant enzymes. Meanwhile, exogenous 10 -9 M KT treatment significantly enhanced the expression of antioxidant enzymes, heat activation, and defense-related genes. In conclusion, exogenous KT treatment regulates heat tolerance in rice seedlings by modulating the dynamic balance of ROS in plants under heat stress.

The chronic exposure of skin to ultraviolet (UV) radiation causes adverse dermal reactions, such as erythema, sunburn, photoaging, and cancer, by altering several signalling pathways associated with oxidative stress, inflammation, and DNA damage. One of the possible UV light protection strategies is the use of dermal photoprotective preparations. The plant hormone kinetin (N6-furfuryladenine; KIN) exhibits antioxidant and anti-senescent effects in human cells. Topically applied KIN also reduced some of the clinical signs of photodamaged skin. To improve the biological activities of KIN, several derivatives have been recently prepared and their beneficial effects on cell viability of skin cells exposed to UVA and UVB light were screened. Two potent candidates, 6-(tetrahydrofuran-2-yl)methylamino-9-(tetrahydrofuran-2-yl)purine (HEO) and 6-(thiophen-2-yl)methylamino-9-(tetrahydrofuran-2-yl)purine (HEO6), were identified. Here the effects of KIN, its N9-substituted derivatives the tetrahydropyran-2-yl derivative of KIN (THP), tetrahydrofuran-2-yl KIN (THF), HEO and HEO6 (both THF derivatives) on oxidative stress, apoptosis and inflammation in UVA- or UVB-exposed skin cell was investigated. Human primary dermal fibroblasts and human keratinocytes HaCaT pre-treated with the tested compounds were then exposed to UVA/UVB light using a solar simulator. All compounds effectively prevented UVA-induced ROS generation and glutathione depletion in both cells. HEO6 was found to be the most potent. All compounds also reduced UVB-induced caspase-3 activity and interleukin-6 release. THP and THF exhibited the best UVB protection. In conclusion, our results demonstrated the UVA- and UVB-photoprotective potential of KIN and its derivatives. From this point of view, they seem to be useful agents for full UV spectrum protective dermatological preparations., (© 2022. The Author(s), under exclusive licence to European Photochemistry Association, European Society for Photobiology.)

Motivated by the clinical success of gold(I) metallotherapeutic Auranofin in the effective treatment of both inflammatory and cancer diseases, we decided to prepare, characterize, and further study the [Au(kin)(PPh 3 )] complex ( 1 ), where Hkin = kinetin, 6-furfuryladenine, for its in vitro anti-cancer and anti-inflammatory activities. The results revealed that the complex ( 1 ) had significant in vitro cytotoxicity against human cancer cell lines (A2780, A2780R, PC-3, 22Rv1, and THP-1), with IC 50 ≈ 1-5 μM, which was even significantly better than that for the conventional platinum-based drug Cisplatin while comparable with Auranofin . Although its ability to inhibit transcription factor NF-κB activity did not exceed the comparative drug Auranofin , it has been found that it is able to positively influence peroxisome-proliferator-activated receptor-gamma (PPARγ), and as a consequence of this to have the impact of moderating/reducing inflammation. The cellular effects of the complex ( 1 ) in A2780 cancer cells were also investigated by cell cycle analysis, induction of apoptosis, intracellular ROS production, activation of caspases 3/7 and disruption of mitochondrial membrane potential, and shotgun proteomic analysis. Proteomic analysis of R2780 cells treated with complex ( 1 ) and starting compounds revealed possible different places of the effect of the studied compounds. Moreover, the time-dependent cellular accumulation of copper was studied by means of the mass spectrometry study with the aim of exploring the possible mechanisms responsible for its biological effects.

Orally available antivirals against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are necessary because of the continuous circulation of new variants that challenge immunized individuals. Because severe COVID-19 is a virus-triggered immune and inflammatory dysfunction, molecules endowed with both antiviral and anti-inflammatory activity are highly desirable. We identified here that kinetin (MB-905) inhibits the in vitro replication of SARS-CoV-2 in human hepatic and pulmonary cell lines. On infected monocytes, MB-905 reduced virus replication, IL-6 and TNFα levels. MB-905 is converted into its triphosphate nucleotide to inhibit viral RNA synthesis and induce error-prone virus replication. Coinhibition of SARS-CoV-2 exonuclease, a proofreading enzyme that corrects erroneously incorporated nucleotides during viral RNA replication, potentiated the inhibitory effect of MB-905. MB-905 shows good oral absorption, its metabolites are stable, achieving long-lasting plasma and lung concentrations, and this drug is not mutagenic nor cardiotoxic in acute and chronic treatments. SARS-CoV-2-infected hACE-mice and hamsters treated with MB-905 show decreased viral replication, lung necrosis, hemorrhage and inflammation. Because kinetin is clinically investigated for a rare genetic disease at regimens beyond the predicted concentrations of antiviral/anti-inflammatory inhibition, our investigation suggests the opportunity for the rapid clinical development of a new antiviral substance for the treatment of COVID-19., (© 2023. The Author(s).)

Finger millet [Eleusine coracana (L.) Gaertn.] is an important cereal because of its mineral-nutrition value. With the increasing demand, there is a pressing need to conserve it through biotechnological approaches. High-frequency somatic embryogenesis from seed-derived callus of E. coracana was developed on Murashige-Skoog (MS) medium supplemented with a combination of auxins [Indole-3-acetic acid (IAA), 2,4-Dichlorophenoxy acetic acid (2,4-D)] and cytokinins [6-Benzylaminopurine (BAP), kinetin (KN)] in different concentrations, ranging from 0.1 to 5.0 mg L -1 . Seeds cultured on this medium produced three different types of primary callus. Type I callus was very compact and dark brown, type II callus was light brownish and type III callus appeared whitish and light brown. All three types of calli had differential proliferation responses. Type II compact brown calli were obtained on the MS medium supplemented with 1.0 and 1.5 mg 2,4-Dichlorophenoxy acetic acid L -1 and 0.5 mg kinetin L -1 . Friable yellowish embryogenic calli with a large number of somatic embryos were developed within 60 days after being transferred to auxins and cytokinin (1.0 and 1.5 mg 2,4-Dichlorophenoxy acetic acid L -1 and 0.5 mg Kinetin L -1 ) along with 200 mg casein hydrolysate L -1 . Germination of somatic embryos on a half-strength MS medium supplemented with 0.1% Kinetin led to the development of healthy plantlets within 30 days. Genetic fingerprinting using random amplified polymorphic DNA (RAPD) revealed high levels of genetic fidelity. The study provides methods and hormonal concentrations required to develop somatic embryos in E. coracana for its genetic improvement and conservation., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Novel computational methods such as artificial neural networks (ANNs) can facilitate modeling and predicting results of tissue culture experiments and thereby decrease the number of experimental treatments and combinations. The objective of the current study is modeling and predicting in vitro shoot proliferation of Erysimum cheiri (L.) Crantz, which is an important bedding flower and medicinal plant. Its micropropagation has not been investigated before and as a case study multilayer perceptron- non-dominated sorting genetic algorithm-II (MLP-NSGAII) can be applied. MLP was used for modeling three outputs including shoots number (SN), shoots length (SL), and callus weight (CW) based on four variables including 6-benzylaminopurine (BAP), kinetin (Kin), 1-naphthalene acetic acid (NAA) and gibberellic acid (GA3). The R2 correlation values of 0.84, 0.99 and 0.93 between experimental and predicted data were obtained for SN, SL, and CW, respectively. These results proved the high accuracy of MLP model. Afterwards the model connected to Non-dominated Sorting Genetic Algorithm-II (NSGA-II) was used to optimize input variables for obtaining the best predicted outputs. The results of sensitivity analysis indicated that SN and CW were more sensitive to BA, followed by Kin, NAA and GA. For SL, more sensitivity was obtained for GA3 than NAA. The validation experiment indicated that the difference between the validation data and MLP-NSGAII predicted data were negligible. Generally, MLP-NSGAII can be considered as a powerful method for modeling and optimizing in vitro studies., Competing Interests: The authors have declared that no competing interests exist.

Increasing ultraviolet (UV) radiation is causing oxidative stress that accounts for growth and yield losses in the present era of climate change. Plant hormones are useful tools for minimizing UV-induced oxidative stress in plants, but their putative roles in protecting tomato development under UVC remain unknown. Therefore, we investigated the underlying mechanism of pre-and post-kinetin (Kn) treatments on tomato plants under UVC stress. The best dose of Kn was screened in the preliminary experiments, and this dose was tested in further experiments. UVC significantly decreases growth traits, photosynthetic pigments, protein content, and primary metabolites (proteins, carbohydrates, amino acids) but increases oxidative stress biomarkers (lipid peroxidation, lipoxygenase activity, superoxide anion, hydroxyl radical, and hydrogen peroxide) and proline content. Treatment of pre-and post-kinetin spraying to tomato plants decreases UVC-induced oxidative stress by restoring the primary and secondary metabolites' (phenolic compounds, flavonoids, and anthocyanins) status and upregulating the antioxidant defense systems (non-enzymatic antioxidants as ascorbate, reduced glutathione, α-tocopherol as well as enzymatic antioxidants as superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase, glutathione-S-transferase, and phenylalanine ammonia-lyase). Thus, the application of Kn in optimum doses and through different modes can be used to alleviate UVC-induced negative impacts in tomato plants., (© 2022. The Author(s).)

Background: Pokeweed ( Phytolacca americana L.) is regarded as an invasive plant in many parts of the world but possesses therapeutic characteristics used for antitumor and rheumatism treatment. This study investigated the effects of auxins and four explants on pokeweed callus induction. The effects of cytokinins and combinations between cytokinins and NAA on shoot and root induction were also studied. TPC, TFC and antioxidant activity of calli were screened and compared with other pokeweed plant parts., Methods: Four explants were used to induce callus using 2,4-D and IBA at 1, 2, 3 and 4 mg/l for each auxin. Direct shoot organogenesis from nodal explants was investigated using BAP, kinetin and TDZ (1, 2 and 4 mg/l for each cytokinin). Combined effects between cytokinins and NAA at 0.1, 0.2 and 0.3 mg/l were further simultaneously estimated with root induction. Calli derived from the leaves were compared with other plant parts for TPC, TFC and antioxidant activity using the Folin-Ciocalteu, AlCl 3 colorimetric assay and DPPH assays, respectively., Results: Results showed that MS medium containing 2 mg/l 2,4-D induced callus formation on leaf explants that provided highest fresh and dry weights. Three types of synthetic cytokinins as kinetin, TDZ and BAP were used for direct shoot organogenesis from pokeweed nodes. MS medium containing 2 mg/l kinetin was effective in stimulating normal shoots, with the largest number of shoots and leaves and the longest shoots. The combination between cytokinins and NAA showed no positive effect on shoot and root induction from pokeweed nodal explants. For TPC and TFC determination, pokeweed seeds and leaves possessed the highest phenolic and flavonoid contents, respectively. Highest phenolic content of pokeweed seeds led to lowest IC 50 by DPPH assay. Phenolic content was higher than flavonoid content., Conclusion: Results suggested promising conditions for callus induction. Leaf explants cultured on MS medium with 2 mg/l 2,4-D and nodal explants cultured on MS medium with 2 mg/l kinetin provided the largest number of normal shoots and leaves. NAA did not show positive effects on shoot and root induction when combined with cytokinins. Chemical constituent screening indicated that seeds and leaves provided highest TPC and TFC, respectively, while pokeweed calli contained higher phenolic than flavonoid content. This is the first report describing chemical constituent screening and antioxidant activity of calli and other parts of the pokeweed plant. Results provided significant information to further enhance bioactive compound contents of pokeweed calli using elicitation methods., Competing Interests: The authors declare there are no competing interests., (©2022 Trunjaruen et al.)

Thunbergia coccinea Wall. ex D. Don being a rare, ornamental and medicinal plant of India, is needed to propagate for conserving the germplasm and analyzing its phytochemical compounds in the future. A reliable protocol for direct in vitro propagation using nodal shoot meristem of T. coccinea as explant was standardized. The highest number of shoots per explant (22.17 ± 0.54) with maximum shoot length (2.36 ± 0.28) in cm was obtained in Murashige and Skoog (MS) medium supplemented with 9.70 µM of 6-furfurylaminopurine (Kinetin) and 0.053 µM of α-naphthaleneacetic acid (NAA) combination, among all the different plant growth regulators (PGR's) and concentrations tested. The aforesaid PGR's combination was optimum for axillary shoot bud induction and multiplication in T. coccinea. The best rooting was observed on the half-strength MS medium fortified with 2.68 µM NAA with the highest number of roots per shoot (3.75 ± 0.12) and maximum length (5.22 ± 0.32) in cm. All the in vitro raised plantlets were acclimatized in sterile sand and soil mixture (1:1) with a survival rate of 70% on earthen pots under greenhouse conditions. PCR-based RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter-Simple Sequence Repeat) molecular markers were employed to determine the genetic homogeneity amongst the plantlets. Twelve (12) RAPD and nine (9) ISSR primers developed a total of 104 and 91 scorable bands, respectively. The band profiles of micropropagated plantlets were monomorphic to the mother, donor in vivo plant, and similarity values varied from 0.9542-1.000. The dendrogram generated through UPGMA (unweighted pair group method with arithmetic mean) showed 99% similarities amongst all tested plants confirming the genetic uniformity of in vitro raised plants., (© 2022. The Author(s).)

In recent years, improving plants' resistance towards abiotic stresses with exogenous application of plant growth regulators and nutrients has emerged as a matter of great interest. The present study assessed the potential roles of kinetin (Kn, 0.2 mM) and calcium (Ca, 2 mM) in mitigating the salt (200 mM NaCl) induced inhibitory effects on seed germination and growth of choysum seedlings. The results indicated that NaCl stress significantly reduced the seed germination percentage (42.6%), germination potential (42.0%), germination index (52.1%), seedling vigor index (65.2%), and declined the fresh weight (43.8%), dry weight (52.2%), radicle length (37.2%), and plumule length (41.2%) of germinated seeds, compared to control treatment. The delayed germination and decrease in seedling growth were positively correlated with salinity-induced hormonal imbalance, ion toxicity, and oxidative stress. However, Kn and Ca pretreatment partially mitigated the adverse effects of NaCl stress, evident by early germination and enhanced seedling growth. Kn and Ca effectively increased the accumulation of proline, soluble protein, and soluble sugars, and upregulated the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase that significantly reduced the production of malondialdehyde, hydrogen peroxide, and superoxide anions in germinating seeds, thereby minimizing the NaCl-induced oxidative damages. Moreover, Kn and Ca pretreatment counteracted the NaCl-induced ionic toxicity by decreasing Na + and increasing K + contents and maintained a balanced Na + /K + ratio in radicles and plumules of choysum seeds. Additionally, Kn and Ca under NaCl stress enhanced hormonal regulation by decreasing the ABA levels with a concomitant increase of GAs (especially GA 4 ) levels and promoted early germination. Remarkably, the co-application of Kn and Ca was most effective by completely counteracting the inhibitory effects of NaCl and maintaining seed germination kinetics, seedling growth, and biochemical parameters almost similar to that in the stress-free control treatment. These results demonstrate that supplementation of Kn and Ca on choysum seeds is an effective chemical strategy regulating the various physiological and biochemical responses that would result in better germination and growth of seeds under stress conditions., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Cell death (CD) may be induced by endogenous or exogenous factors and contributes to all the steps of plant development. This paper presents results related to the mechanism of CD regulation induced by kinetin (Kin) in the root cortex of Vicia faba ssp. minor. To explain the process, 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55), adenine (Ad), 5'-amine-5'-deoxyadenosine (Ado) and N-(2-chloro-4-piridylo)-N'-phenylurea (CPPU) were applied to (i) block cytokinin receptors (CKs) and inhibit the activities of enzymes of CK metabolism, i.e., (ii) phosphoribosyltransferase, (iii) kinases, and (iv) oxidases, respectively. Moreover, ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), lanthanum chloride (LaCl 3 ), ruthenium red (RRed) and cyclosporine A (CS-A) were applied to (i) chelate extracellular calcium ions (Ca 2+ ) as well as blocks of (ii) plasma-, (iii) endoplasmic reticulum- (ER) membrane Ca 2+ ion channels and (iv) mitochondria- (MIT) Ca 2+ ions release by permeability transition por (PTP), respectively. The measured physiological effectiveness of these factors was the number of living and dying cortex cells estimated with orange acridine (OA) and ethidium bromide (EB), the amounts of cytosolic Ca 2+ ions with chlortetracycline (CTC) staining and the intensity of chromatin and Ca 2+ -CTC complex fluorescence, respectively. Moreover, the role of sorafenib, an inhibitor of RAF kinase, on the vitality of cortex cells and ethylene levels as well as the activities of RAF-like kinase and MEK2 with Syntide-2 and Mek2 as substrates were studied. The results clarified the previously presented suggestion that Kin is converted to appropriate ribotides (5'-monophosphate ribonucleotides), which cooperate with the ethylene and Ca 2+ ion signalling pathways to transduce the signal of kinetin-programmed cell death (Kin-PCD). Based on the present and previously published results related to Kin-PCD, the crosstalk between ethylene and MAP kinase signalling, as well as inhibitors of CK receptors and enzymes of their metabolism, is proposed., (© 2021. The Author(s).)

Kinetin or N6-furfuryladenine (K) belongs to a class of plant hormones called cytokinins, which are biologically active molecules modulating many aspects of plant growth and development. However, biological activities of cytokinins are not only limited to plants; their effects on animals have been widely reported in the literature. Here, we found that Kinetin is a potent small molecule that efficiently stimulates differentiation of C2C12 myoblasts into myotubes in vitro. The highest efficacy was achieved at 1μM and 10μM Kinetin concentrations, in both mitogen-poor and rich media. More importantly, Kinetin was able to strongly stimulate the MyoD-dependent conversion of fibroblasts into myotubes. Kinetin alone did not give rise to fibroblast conversion and required MyoD; this demonstrates that Kinetin augments the molecular repertoire of necessary key regulatory factors to facilitate MyoD-mediated myogenic differentiation. This novel Kinetin pro-myogenic function may be explained by its ability to alter intracellular calcium levels and by its potential to impact on Reactive Oxygen Species (ROS) signalling. Taken together, our findings unravel the effects of a new class of small molecules with potent pro-myogenic activities. This opens up new therapeutic avenues with potential for treating skeletal muscle diseases related to muscle aging and wasting., Competing Interests: The authors have declared that no competing interests exist.

Background: Following stroke, changes in neuronal connectivity in tissue surrounding the infarct play an important role in both spontaneous recovery of neurological function and in treatment-induced improvements in function. Microglia and astrocytes influence this process through direct interactions with the neurons and as major determinants of the local tissue environment. Subpopulations of peri-infarct glia proliferate early after stroke providing a possible target to modify recovery. Treatment with cell cycle inhibitors can reduce infarct volume and improve functional recovery. However, it is not known whether these inhibitors can influence neurological function or alter the responses of peri-infarct glia without reducing infarction. The present study aimed to address these issues by testing the effects of the cell cycle inhibitor, olomoucine, on recovery and peri-infarct changes following photothrombotic stroke., Methods: Stroke was induced by photothrombosis in the forelimb sensorimotor cortex in Sprague-Dawley rats. Olomoucine was administered at 1 h and 24 h after stroke induction. Forelimb function was monitored up to 29 days. The effects of olomoucine on glial cell responses in peri-infarct tissue were evaluated using immunohistochemistry and Western blotting., Results: Olomoucine treatment did not significantly affect maximal infarct volume. Recovery of the affected forelimb on a placing test was impaired in olomoucine-treated rats, whereas recovery in a skilled reaching test was substantially improved. Olomoucine treatment produced small changes in aspects of Iba1 immunolabelling and in the number of CD68-positive cells in cerebral cortex but did not selectively modify responses in peri-infarct tissue. The content of the astrocytic protein, vimentin, was reduced by 30% in the region of the lesion in olomoucine-treated rats., Conclusions: Olomoucine treatment modified functional recovery in the absence of significant changes in infarct volume. The effects on recovery were markedly test dependent, adding to evidence that skilled tasks requiring specific training and general measures of motor function can be differentially modified by some interventions. The altered recovery was not associated with specific changes in key responses of peri-infarct microglia, even though these cells were considered a likely target for early olomoucine treatment. Changes detected in peri-infarct reactive astrogliosis could contribute to the altered patterns of functional recovery., (© 2021. The Author(s).)

Cytokinins (CKs) plays a key role in plant adaptation over a range of different stress conditions. Here, we analyze the effects of a cytokinin (i.e., kinetin, KN) on the growth, photosynthesis (rate of O2 evolution), PS II photochemistry and AsA-GSH cycle in Trigonella seedlings grown under cadmium (Cd) stress. Trigonella seeds were sown in soil amended with 0, 3 and 9 mg Cd kg-1 soil, and after 15 days resultant seedlings were sprayed with three doses of KN, i.e.,10 μM (low, KNL), 50 μM (medium, KNM) and 100 μM (high, KNH); subsequent experiments were performed after 15 days of KN application, i.e., 30 days after sowing. Cadmium toxicity induced oxidative damage as shown by decreased seedling growth and photosynthetic pigment production (Chl a, Chl b and Car), rates of O2-evolution, and photochemistry of PS II of Trigonella seedlings, all accompanied by an increase in H2O2 accumulation. Supplementation with doses of KN at KNL and KNM significantly improved the growth and photosynthetic activity by reducing H2O2 accumulation through the up-regulation AsA-GSH cycle. Notably, KNL and KNM doses stimulated the rate of enzyme activities of APX, GR and DHAR, involved in the AsA-GSH cycle thereby efficiently regulates the level of AsA and GSH in Trigonella grown under Cd stress. The study concludes that KN can mitigate the damaging effects of Cd stress on plant growth by maintaining the redox status (>ratios: AsA/DHA and GSH/GSSG) of cells through the regulation of AsA-GSH cycle at 10 and 50 μM KN under Cd stress conditions. At 100 μM KN, the down-regulation of AsA-GSH cycle did not support the growth and PS II activity of the test seedlings., Competing Interests: The authors have declared that no competing interests exist.

Kinetin (N 6 -furfuryladenine), a plant growth substance of the cytokinin family, has been shown to modulate aging and various age-related conditions in animal models. Here we report the synthesis of kinetin isosteres with the purine ring replaced by other bicyclic heterocycles, and the biological evaluation of their activity in several in vitro models related to neurodegenerative diseases. Our findings indicate that kinetin isosteres protect Friedreich́s ataxia patient-derived fibroblasts against glutathione depletion, protect neuron-like SH-SY5Y cells from glutamate-induced oxidative damage, and correct aberrant splicing of the ELP1 gene in fibroblasts derived from a familial dysautonomia patient. Although the mechanism of action of kinetin derivatives remains unclear, our data suggest that the cytoprotective activity of some purine isosteres is mediated by their ability to reduce oxidative stress. Further, the studies of permeation across artificial membrane and model gut and blood-brain barriers indicate that the compounds are orally available and can reach central nervous system. Overall, our data demonstrate that isosteric replacement of the kinetin purine scaffold is a fruitful strategy for improving known biological activities of kinetin and discovering novel therapeutic opportunities., (Copyright © 2021. Published by Elsevier Ltd.)

Plant hormones are small regulatory molecules that exert pharmacological actions in mammalian cells such as anti-oxidative and pro-metabolic effects. Kinetin belongs to the group of plant hormones cytokinin and has been associated with modulatory functions in mammalian cells. The mammalian adenosine receptor (A2a-R) is known to modulate multiple physiological responses in animal cells. Here, we describe that kinetin binds to the adenosine receptor (A2a-R) through the Asn253 residue in an adenosine dependent manner. To harness the beneficial effects of kinetin for future human use, we assess its acute toxicity by analyzing different biochemical and histological markers in rats. Kinetin at a dose below 1 mg/kg had no adverse effects on the serum level of glucose or on the activity of serum alanine transaminase (ALT) or aspartate aminotransferase (AST) enzymes in the kinetin treated rats. Whereas, creatinine levels increased after a kinetin treatment at a dose of 0.5 mg/kg. Furthermore, 5 mg/kg treated kinetin rats showed normal renal corpuscles, but a mild degeneration was observed in the renal glomeruli and renal tubules, as well as few degenerated hepatocytes were also observed in the liver. Kinetin doses below 5 mg/kg did not show any localized toxicity in the liver and kidney tissues. In addition to unraveling the binding interaction between kinetin and A2a-R, our findings suggest safe dose limits for the future use of kinetin as a therapeutic and modulatory agent against various pathophysiological conditions.

Small-molecule compound-based therapies have provided new insights into cancer treatment against mitochondrial impairment. N6-furfuryladenosine (kinetin riboside, KR) is a purine derivative and an anticancer agent that selectively affects the molecular pathways crucial for cell growth and apoptosis by interfering with mitochondrial functions and thus might be a potential mitotoxicant. Metabolism of cancer cells is predominantly based on the Crabtree effect that relies on glucose-induced inhibition of cell respiration and thus on oxidative phosphorylation (OXPHOS), which supports the survival of cancer cells in metabolic stress conditions. The simplest way to circumvent this phenomenon is to replace glucose with galactose in the culture environment. Consequently, cells become more sensitive to mitochondrial perturbations caused by mitotoxicants. In the present study, we evaluated several cellular parameters and investigated the effect of KR on mitochondrial functions in HepG2 cells forced to rely mainly on OXPHOS. We showed that KR in the galactose environment is a more potent apoptosis-inducing agent. KR decreases the mitochondrial membrane potential, reduces glutathione level, depletes cellular ATP, and induces reactive oxygen species (ROS) production in the OXPHOS state, leading to the loss of cell viability. Taken together, these results demonstrate that KR directly acts on the mitochondria to limit their function and that the sensitivity of cells is dependent on their ability to cope with energetic stress.

Callus from Nicotiana tabacum is used as a model in plant developmental research. We tested several phytohormone (Indoleacetic acid - IAA; 2,4-Dichlorophenoxyacetic acid - 2,4-D; kinetin - KIN; 6-Benzylaminopurine - BAP) combinations to compare different approaches to callus induction directly from the seeds of Nicotiana tabacum. Callus formation was observed up to 4 weeks after sowing and the most effective were 0.5 mg/L of 2,4-D with 0.25 mg/L of BAP and 2 mg/L 2,4-D with 1 mg/L of BAP. The calli were green, photosynthetically active and after 6 weeks of growth, no stress symptoms (estimated on the basis of fluorescence of chlorophyll a in photosystem II) were noticed.

Background: Moringa stenopetala belongs to the flowering family Moringaceae and genus Moringa. It is often referred to as the East African Moringa tree because it is native only to southern Ethiopia and northern Kenya. The expansion of its cultivation and utilization throughout the world especially in Africa is becoming important. For such expansion, the existing propagation method is limiting, so it needs a good propagation system to supply enough planting material with a uniform genotype. Therefore, the main objective of this study was to optimize an in vitro shoot multiplication protocol for M. stenopetala by using shoot tip as explants., Results: Shoots were sterilized and cultured on Muraghige and Skoog (MS) medium for in vitro shoot initiation. For multiple shoot induction, the explants were cultured on MS medium supplemented with different concentrations of kinetin (0.5, 1.0, 1.5, 2.0, 2.5 mg/L) with Indole-3- butyric acid (IBA) or α -naphthalene acetic acid (NAA) (0.01, 0.1, 0.5 mg/L) and maintained at 25 ± 2 °C for four weeks. Rooting was achieved by culturing well developed shoots in half-strength MS medium containing IBA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L), NAA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L), and 0.5 mg/L IBA with NAA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L). Statistical analysis revealed that there was a significant difference among all treatments applied in both shoot multiplication and rooting experiments. The maximum number of shoots per explant (3.43 ± 1.41) and 7.97 ± 4.18 leaves per explant were obtained on MS medium containing 0.5 mg/L kinetin with 0.01 mg/LNAA. The highest mean number of roots per shoot (1.63 ± 1.03) and mean root length (0.87 ± 1.22 cm) were obtained on MS medium containing 1.0 mg/LNAA and 0.1 mg/LIBA alone respectively. After acclimatization, 76% of plants were survived in the greenhouse., Conclusion: In general, using NAA with kinetin for shoot multiplication was effective than kinetin with IBA. On the other hand, the application of 1.0 mg/L NAA alone and 1.0 mg/L NAA with 0.5 mg/L IBA were more effective for root induction.

Background: Cyanobacteria are well known for their inherent ability to serve as atmospheric nitrogen fixers and as bio-fertilizers; however, increased contaminants in aquatic ecosystem significantly decline the growth and function of these microbes in paddy fields. Plant growth regulators play beneficial role in combating the negative effects induced by heavy metals in photoautotroph. Current study evaluates the potential role of indole acetic acid (IAA; 290 nm) and kinetin (KN; 10 nm) on growth, nitrogen metabolism and biochemical constituents of two paddy field cyanobacteria Nostoc muscorum ATCC 27893 and Anabaena sp. PCC 7120 exposed to two concentrations of chromium (Cr VI ; 100 μM and 150 μM)., Results: Both the tested doses of Cr VI declined the growth, ratio of chlorophyll a to carotenoids (Chl a/Car), contents of phycobiliproteins; phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE), protein and carbohydrate associated with decrease in the inorganic nitrogen (nitrate; NO 3 - and nitrite; NO 2 - ) uptake rate that results in the decrease in nitrate and ammonia assimilating enzymes; nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT) except glutamate dehydrogenase (GDH). However, exogenous supplementation of IAA and KN exhibited alleviating effects on growth, nitrogen metabolism and exopolysaccharide (EPS) (first protective barrier against metal toxicity) contents in both the cyanobacteria, which probably occurred as a result of a substantial decrease in the Cr uptake that lowers the damaging effects., Conclusion: Overall result of the present study signifies affirmative role of the phytohormone in minimizing the toxic effects induced by chromium by stimulating the growth of cyanobacteria thereby enhancing its ability as bio-fertilizer that improved fertility and productivity of soil even in metal contaminated condition.

In the present study, the impact of eight phytohormones from six different classes on the growth, lipid and docosahexaenoic acid (DHA) biosynthetic capacity of Aurantiochytrium sp. SW1 (SW1) was evaluated. Kinetin (KIN), jasmonic acid (JA) and gibberellic acid (GA) significantly enhanced the growth and DHA production of SW1 by 16%-28% and 66%-84% in comparison to the control, respectively. The synergistic effect of these three phytohormones, evaluated by the response surface methodology (RSM), showed that a combination of 3.6 mg/L GA, 2.0 mg/L KIN and 20.0 mg/L JA further increased the growth and DHA production of SW1 by 16% to 28% and 22% to 36%, respectively, in comparison to the individual supplementation. The synergistic effect of these phytohormones was also shown to be time-dependent, where feeding at 24 h of cultivation led to 15%, 26% and 35% further increments in the biomass, lipid and DHA production in comparison to that of 0 h, respectively. The determination of stress markers, antioxidant enzymes and key enzymes involved in fatty acid biosynthesis aided to elucidate the potential mechanism underlying the improvement of growth and DHA production by SW1 at various times of feeding. Supplementation with the phytohormones at 24 h exhibited the maximum impact on reducing the level of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as augmented the antioxidants (superoxide dismutase and catalase) and key metabolic enzymes involved in lipogenesis (malic, glucose-6-phosphate dehydrogenase and ATP-citrate lyase) in comparison to the control and other time points. This study signifies the potential application of phytohormones for improving the growth, lipid and DHA production in Aurantiochytrium spp.

Light emitting diodes (LEDs) have become a promising technology for agriculture and horticulture. I investigated the effects of white (W), red (R) and blue (B) LED lights on the propagation of Limnophila aromatica (Lamk.) Merr. and Rotala rotundifolia (Buch-Ham. ex Roxb) Koehne using tissue culture. The shoot tip explants of L. aromatica and R. rotundifolia under different light environments were cultured in Murashige and Skoog (MS) basic nutrient medium with 6-benzylaminopurine (BAP) (0.05, 0.10 and 0.20 mg/l) and gibberellic acid (GA 3 ) 0.25 mg/l) + kinetin (KIN) 0.25, 0.50 and 0.75 mg/l. The explants grown under combinations of white, red and blue LEDs were more effective for propagation of the plants in vitro. In L. aromatica , the maximum number of shoots/explant and the longest shoot lengths were obtained using the combination of white, red and blue LED lights in a 1:2:1 ratio in MS medium supplemented with 0.10 and 0.20 mg/l BAP. In R. rotundifolia , the maximum shoots/explant and shoot lengths were obtained in the explants using the combination of white, red and blue LED lights in a 1:2:1 ratio in the MS culture media fortified with 0.25 mg/l GA 3 + 0.25 and 0.75 mg/l KIN. After the regenerated shoots were rooted, they were adapted successfully to external conditions. LEDs have significant advantages over fluorescent lights.

The epithelial-mesenchymal transition (EMT) is a molecular process connected to higher expression of vimentin and increased activity of transcription factors (Snail, Twist) which restrains E-cadherin. EMT has been linked to prostate cancer metastatic potential, therapy resistance, and poor outcomes. Kinetin riboside (9-(b-dribofuranosyl)-6-furfurylaminopurine, KR) is a naturally occurring cytokinin, which induces apoptosis and shows strong antiproliferative activity against various human cancer cell lines. To establish the effect of KR on human prostate cell lines, expression of, e.g. AR, E-, N-cadherins, Vimentin, Snail, Twist, and MMPs, was analysed at mRNA and protein levels using Western Blot and RT-PCR and/or RQ-PCR techniques. KR inhibited the growth of human prostate cancer cells, but also, to a small extent, of normal cells. This effect depended on the type of the cells and their androgen sensitivity. KR also decreased the level of p-Akt, which takes part in androgen signalling modulation. The antiapoptotic Bcl-2 protein was down-regulated in cancer cell lines, while that of Bax is up-regulated upon KR exposure. KR contributed to re-expression of the E-cadherin as well as to significant changes in cell migration. Taken together, our results indicate for the first time that KR can be proposed as a factor for signalling pathways regulation that participates in the inhibition of development of aggressive forms of prostate cancer, and may alter the approach to therapeutic interventions. We propose KR as a potent inhibitor of EMT in human prostate cells.

Salinity stress reduces growth and yield productivity of most crop plants. Potentiality of kinetin (Kn) and epi-brassinolide (EBL), either individually or combinedly in preventing the salinity (100 mM NaCl) stress mediated oxidative damage and photosynthetic inhibition was studied in Solanum lycopersicum. Combined application of Kn and EBL imparted much prominent impact on the growth, photosynthesis and metabolism of antioxidants, osmolytes and secondary metabolites. Synthesis of chlorophylls and carotenoids increased and the photosynthetic parameters like stomatal conductance, intercellular CO 2 concentration and net photosynthesis were significantly improved due to application of Kn and EBL. Photosystem II functioning (Fv/Fm), photochemical quenching and electron transport rate (ETR) improved significantly in Kn and EBL treated plants imparting significant decline in salinity induced non-photochemical quenching. Exogenous Kn and EBL effectively prevented the oxidative damage by significantly declining the generation of hydrogen peroxide and superoxide under saline and non-saline conditions as reflected in lowered lipid peroxidation and electrolyte leakage. Reduced oxidative damage in Kn and EBL treated plants was accompanied down-regulation of protease and lipoxygenase concomitant with up-regulation of the antioxidant system and the accumulation of compatible osmolytes. Treatment of Kn and EBL proved effective in enhancing the contents of redox homeostasis, ascorbic acid and reduced glutathione, and the secondary metabolites assisting the enzymatic antioxidant system in combating the salinity stress efficiently. Results suggest that combined application of Kn and EBL regulate growth and photosynthesis in tomato more effectively than their individual application through a probable regulatory crosstalk mechanism., Competing Interests: Declaration of competing interest The authors declare that no conflict of interest exists., (Copyright © 2019. Published by Elsevier Masson SAS.)

The somatic embryogenesis (SE) process of plants is regulated by exogenous hormones. During the SE, different genes sensitively respond to hormone signals through complex regulatory networks to exhibit plant totipotency. When cultured in indole-3-butyric acid (IBA) concentration gradient medium supplemented with 0 mg dm -3 , 0.025 mg dm -3 , and 0.05 mg dm -3 IBA, the callus differentiation rate first increased then decreased in cotton. To characterize the molecular basis of IBA-induced regulating SE, transcriptome analysis was conducted on embryogenic redifferentiation. Upon the examination of the IBA's embryogenic inductive effect, it was revealed that pathways related to plant hormone signal transduction and alcohol degradation were significantly enriched in the embryogenic responsive stage (5 days). The photosynthesis, alcohol metabolism and cell cycle pathways were specifically regulated in the pre-embryonic initial period (20 days). Upon the effect of the IBA dose, in the embryogenic responsive stage (5 days), the metabolism of xenobiotics by the cytochrome P450 pathway and secondary metabolism pathways of steroid, flavonoid, and anthocyanin biosynthesis were significantly enriched. The phenylpropanoid, brassinosteroid, and anthocyanin biosynthesis pathways were specifically associated in the pre-embryonic initial period (20 days). At different developmental stages of embryogenic induction, photosynthesis, flavonoid biosynthesis, phenylpropanoid biosynthesis, mitogen-activated protein kinase (MAPK) signaling, xenobiotics metabolism by cytochrome P450, and brassinosteroid biosynthesis pathways were enriched at low a IBA concentration. Meanwhile, at high IBA concentration, the carbon metabolism, alcohol degradation, circadian rhythm and biosynthesis of amino acids pathways were significantly enriched. The results reveal that complex regulating pathways participate in the process of IBA-induced redifferentiation in cotton somatic embryogenesis. In addition, collections of potential essential signaling and regulatory genes responsible for dose IBA-induced efficient embryogenic redifferentiation were identified. Quantitative real-time PCR (qRT-PCR) was performed on the candidate genes with different expression patterns, and the results are basically consistent with the RNA-seq data. The results suggest that the complicated and concerted IBA-induced mechanisms involving multiple cellular pathways are responsible for dose-dependent plant growth regulator-induced SE. This report represents a systematic study and provides new insight into molecular signaling and regulatory basis underlying the process of dose IBA-induced embryogenic redifferentiation during SE.

It has been more than 60 years since the discovery of kinetin, the first known member of a group of plant hormones called cytokinins. In this review we summarize the health-promoting activity of kinetin in animal systems, ranging from cells cultured in vitro through invertebrates to mammals. Kinetin has been shown to modulate aging, to delay age-related physiological decline and to protect against some neurodegenerative diseases. We also review studies on its mechanism of action, as well as point out gaps in our current knowledge., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In the present work, non-targeted metabolomics was used to investigate the seed response to kinetin, a phytohormone with potential roles in seed germination, still poorly explored. The aim of this study was to elucidate the metabolic signatures of germination triggered by kinetin and explore changes in metabolome to identify novel vigor/stress hallmarks in Medicago truncatula. Exposure to 0.5 mM kinetin accelerated seed germination but impaired seedling growth. Metabolite composition was investigated in seeds imbibed with water or with 0.5 mM kinetin collected at 2 h and 8 h of imbibition, and at the radicle protrusion stage. According to Principal Component Analysis, inositol pentakisphosphate, agmatine, digalactosylglycerol, inositol hexakisphosphate, and oleoylcholine were the metabolites that mostly contributed to the separation between 2 h, 8 h and radicle protrusion stage, irrespective of the treatment applied. Overall, only 27 metabolites showed significant changes in mean relative contents triggered by kinetin, exclusively at the radicle protrusion stage. The observed metabolite depletion might associate with faster germination or regarded as a stress signature. Results from alkaline comet assay, highlighting the occurrence of DNA damage at this stage of germination, are consistent with the hypothesis that prolonged exposure to kinetin induces stress conditions leading to genotoxic injury.

Cytokinins are a group of plant hormones which play an important role in plant growth and development. They produce various effects when applied to intact plants. They particularly stimulate protein synthesis and participate in cell cycle control. First discovered cytokinin was N6-furfuryladenine (kinetin). It is a strong inhibitor of proteins and nucleic acids oxidation in vitro and in vivo. Both kinetin and its ribosides (N6-furfuryladenosine, kinetin riboside) as natural compounds occur in the milk of coconuts on the nanomole level. Kinetin riboside selectively inhibits the proliferation of cancer cells and induce their apoptosis. This review focuses on the kinetin riboside occurrence, and primarily on its metabolism, and biological activity.

Chemical communication underlies major adaptive traits in plants and shapes the root microbiome. An increasing number of diffusible and/or volatile organic compounds released by bacteria have been identified, which play phytostimulant or protective functions, including dimethyl-hexa-decylamine (DMHDA), a volatile biosynthesized by Arthrobacter agilis UMCV2 that induces jasmonic acid (JA) signaling in Arabidopsis. Here, he found that the growth repressing effects of both DMHDA and JA are antagonized by kinetin and correlated with an inhibition of cytokinin-related ARR5::GUS and TCS::GFP expression in Arabidopsis primary roots. Moreover, we demonstrate that shoot supplementation of JA triggers JAZ1 expression both locally and systemically and represses cytokinin-dependent promoter activity in roots. A similar effect was observed after cotyledon wounding, in which an increase of JA-inducible LOX2:GUS expression represses root growth, which correlates with the loss of TCS::GFP detection at the very root tip. Our data demonstrate that the bacterial volatile DMHDA crosstalks with cytokinin signaling and reveals the downstream antagonistic interaction between JA and cytokinin in controlling root growth.

Main Conclusion: In vitro culture conditions and kinetin induced quantitative modifications in the production of the major volatile constituents in Micromeria croatica plantlets. Antimicrobial activity of methanolic extracts obtained from micropropagated and wild-growing plants was evaluated. Micromeria spp. are aromatic plants, many of which were shown to exhibit various biological effects. The present study aimed to determine the content and the composition of the essential oil of in vitro-cultured Micromeria croatica (Pers.) Schott and to evaluate the in vitro antimicrobial activity of its methanolic extract, in order to compare its phytochemical profile and biological activity with wild-growing plants. Shoots regenerated on MS medium without plant growth regulators (PGRs) or supplemented with kinetin were used for phytochemical analysis. Essential oils from both native plant material and in vitro-cultivated M. croatica plants, with a total of 44 identified constituents, were dominated by oxygenated monoterpenes. Borneol was the main component detected in wild-growing plants (25.28%) and micropropagated plants grown on PGR-free medium (20.30%). Kinetin treatment led to increased oil yield and favored the production of oxygenated monoterpenes, dominated by geranial (33.53%) and cis-p-mentha-1(7),8-dien-ol (23.69%). The percentage of total sesquiterpenoids in micropropagated plant material was considerably lower than in wild-growing plants. In vitro culture conditions and PGRs affected the production of essential oils, inducing quantitative modifications in the production of the major volatile constituents in M. croatica plantlets. The antimicrobial activity of M. croatica methanolic extracts was investigated using the broth microdilution method. Extracts obtained from in vitro cultures generally exhibited greater antibacterial potential, compared to wild-growing plants. Among six bacterial strains tested, Bacillus cereus and Staphylococcus aureus were the most sensitive microorganisms. The present study provided evidence that in vitro culture conditions might favorably affect the antimicrobial activity of M. croatica methanolic extracts.

Rauwolfia tetraphylla L. is an important medicinal plant species which is well known for its pharmaceutically important alkaloids. In the present study, we are reporting about its conservation by in vitro clonal multiplication through the standardized protocol of indirect regeneration by using leaf and stem based callus and assessment of genetic fidelity of acclimated plantlets by start codon targeted (SCoT), inter simple sequence repeats (ISSR), and randomly amplified polymorphic DNA (RAPD) marker based analysis. Initially friable callus was induced in maximum amounts (378.7, 323.8, and 412.8 in mg) from leaf, root, and stem explants on Murashige and Skoog (MS) media supplemented with 5.0 mg/L, 3.0 mg/L of 2,4-dichlorophenoxyacetic acid (2,4-D) and 5.0 mg/L of naphthalene acetic acid (NAA), respectively. Shoot regeneration with the maximum number of shoot buds (25 and 20) was obtained from leaf and stem calluses on MS media supplemented with TDZ (0.25 mg/L) + BAP (2 mg/L). The regenerated shoots were rooted successfully with maximum rooting percentage of 98.0 on full strength MS media amended with IAA (1.0 mg/L) and IBA (1.0 mg/L). The regenerated plantlets were hardened using 2:1 ratio of sterile garden soil and sand, followed by acclimatization in field conditions with 86% of survival. SCoT, ISSR, and RAPD primers based polymerase chain reaction (PCR) analysis was carried out to check possible genetic variations in micro propagated plants in comparison with mother plant. Among the ten SCoT (S), ISSR (R), and RAPD (OPA) primers used, S2, R10, and OPA3 has given good amplification with scorable DNA bands. The results revealed that the regenerated plants did not have any polymorphism with mother plant. Hence, the in vitro regenerated R. tetraphylla plantlets were confirmed as true-to-type.

Steviol glycosides (SGs) and gibberellic acids share a part of their biosynthesis pathways. Despite the widespread studies on the effect of gibberellic acid 3 (GA 3 ), the effect of gibberellic acid 4 and 7 (GA 4/7 ) on Stevia rebaudiana has never been studied. This study aimed at a comparative evaluation of different hormone effects, i.e., 1 mg L -1 GA 4/7 , 1 mg L -1 GA 3 , or 0.5 mg L -1 kinetin and 0.5 mg L -1 6-benzylaminopurine (BAP) (KB 0.5), on in vitro propagation, growth, morphological properties, and content of SGs in leaf samples of stevia. In comparison with the control group (hormone-free), the treatments of KB 0.5 or GA 3 produced the highest biomasses and largest leaf areas. The three hormonal treatments produced a similar number of leaves, the ratio of fresh to dry weight, and leaf length. GA 4/7 -treated explants produced the highest ratio of leaf area to leaf length. The effect of GA 4/7 on shoot elongation was greater than that of the control or even GA 3 . While the effect of GA 3 on rebaudioside-A (Reb-A) production was similar to that of the control (16.2 and 18.04 mg g -1 , respectively), GA 4/7 resulted in a lower amount of it (13.31 mg g -1 ). Except for GA 4/7 , which induced more stevioside accumulation, the treatments' effects were comparable to that of the control. The ratio of stevioside to Reb-A was the highest for GA 4/7 (2.62), followed by GA 3 (1.93), and then the two others. Sum of Reb-A and stevioside content was not changed by the use of any of the treatments., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

While anti-VEGF drugs are commonly used to inhibit pathological retinal and choroidal neovascularization, not all patients respond in an optimal manner. Mechanisms underpinning resistance to anti‑VEGF therapy include the upregulation of other proangiogenic factors. Therefore, therapeutic strategies that simultaneously target multiple growth factor signaling pathways would have significant value. Here, we show that Ca2+/calmodulin-dependent kinase II (CAMKII) mediates the angiogenic actions of a range of growth factors in human retinal endothelial cells and that this kinase acts as a key nodal point for the activation of several signal transduction cascades that are known to play a critical role in growth factor-induced angiogenesis. We also demonstrate that endothelial CAMKIIγ and -δ isoforms differentially regulate the angiogenic effects of different growth factors and that genetic deletion of these isoforms suppresses pathological retinal and choroidal neovascularization in vivo. Our studies suggest that CAMKII could provide a novel and efficacious target to inhibit multiple angiogenic signaling pathways for the treatment of vasoproliferative diseases of the eye. CAMKIIγ represents a particularly promising target, as deletion of this isoform inhibited pathological neovascularization, while enhancing reparative angiogenesis in the ischemic retina.

Familial Dysautonomia (FD) is an autosomal recessive congenital neuropathy that results from a point mutation at the 5' splice site of intron 20 in the IKBKAP gene. This mutation decreases production of the IKAP protein, and treatments that increase the level of the full-length IKBKAP transcript are likely to be of therapeutic value. We previously found that phosphatidylserine (PS), an FDA-approved food supplement, elevates IKAP levels in cells generated from FD patients. Here we demonstrate that combined treatment of cells generated from FD patients with PS and kinetin or PS and the histone deacetylase inhibitor trichostatin A (TSA) resulted in an additive elevation of IKAP compared to each drug alone. This indicates that the compounds influence different pathways. We also found that pridopidine enhances production of IKAP in cells generated from FD patients. Pridopidine has an additive effect on IKAP levels when used in combination with kinetin or TSA, but not with PS; suggesting that PS and pridopidine influence IKBKAP levels through the same mechanism. Indeed, we demonstrate that the effect of PS and pridopidine is through sigma-1 receptor-mediated activation of the BDNF signaling pathway. A combination treatment with any of these drugs with different mechanisms has potential to benefit FD patients., Competing Interests: Funding of this work was provided by Teva Pharmaceutical Industries Ltd. as well as other sources. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This support does not alter our adherence to PLOS ONE policies on sharing data and materials.

It is now well documented that plants produce methane (CH 4 ) under aerobic conditions. However, the nature of methane production in plants and all the potential precursors and environmental factors that can be involved in the process are not fully understood. Earlier studies have suggested several chemical compounds, including the amino acid methionine, as precursors of aerobic methane in plants, but none have explored other amino acids as potential precursors or blue light as a driving force of methane emission. We examined the effects of blue light, and the promoter or inhibitor of endogenous ethylene on methane and ethylene emissions, amino acids, and some plant physiological parameters in canola (Brassica napus). Plants were grown under four light conditions: no supplemental blue light, and low, medium, or high blue light, and exposed to three chemical treatments: no chemical application, ethylene promoter (kinetin), or ethylene inhibitor (silver nitrate). Regardless of chemical treatment, blue light significantly increased methane emission, which was accompanied by decreased plant biomass, gas exchange, and flavonoids, but by increased wax, and most amino acids. This study revealed that blue light drives aerobic methane emission from plants by releasing of methyl group from a number of amino acids, and that the methane production in plants may have several pathways., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: Gymnema sylvestre is a medicinal woody perennial vine known for its sweetening properties and anti-diabetic therapeutic uses in the modern and traditional medicines. Its over-exploitation for the therapeutic uses and to meet the demand of pharmaceutical industry in raw materials supply for the production of anti-diabetic drugs has led to considerable decline in its natural population., Results: An efficient system of shoot bud sprouting from nodal segment explants and indirect plant regeneration from apical meristem-induced callus cultures of G. sylvestre have been developed on Murashige and Skoog (MS) medium amended with concentrations of cytokinins. Of the three growth regulators tested, N 6 -benzylaminopurine (BAP) was the most efficient and 2.0 mg L -1 gave the best shoot formation efficiency. This was followed by thidiazuron (TDZ) and kinetin (Kin) but, most of the TDZ-induced micro shoots showed stunted growth. Multiple shoot formation was observed on medium amended with BAP or TDZ at higher concentrations. The produced micro shoots were rooted on half strength MS medium amended with auxins and rooted plantlets acclimatized with 87% survival of the regenerates., Conclusions: The developed regeneration system can be exploited for genetic transformation studies, particularly when aimed at producing its high yielding cell lines for the anti-diabetic phytochemicals. It also offers opportunities for exploring the expression of totipotency in the anti-diabetic perennial vine.

Familial dysautonomia (FD) is an autonomic and sensory neuropathy caused by a mutation in the splice donor site of intron 20 of the ELP1 gene. Variable skipping of exon 20 leads to a tissue-specific reduction in the level of ELP1 protein. We have shown that the plant cytokinin kinetin is able to increase cellular ELP1 protein levels in vivo and in vitro through correction of ELP1 splicing. Studies in FD patients determined that kinetin is not a practical therapy due to low potency and rapid elimination. To identify molecules with improved potency and efficacy, we developed a cell-based luciferase splicing assay by inserting renilla (Rluc) and firefly (Fluc) luciferase reporters into our previously well-characterized ELP1 minigene construct. Evaluation of the Fluc/Rluc signal ratio enables a fast and accurate way to measure exon 20 inclusion. Further, we developed a secondary assay that measures ELP1 splicing in FD patient-derived fibroblasts. Here we demonstrate the quality and reproducibility of our screening method. Development and implementation of this screening platform has allowed us to efficiently screen for new compounds that robustly and specifically enhance ELP1 pre-mRNA splicing.

Cytokinins (CKs), a class of phytohormone, regulate root growth in a dose-dependent manner. A certain threshold content of CK is required for rapid root growth, but supraoptimal CK content inhibits root growth, and the mechanism of this inhibition remains unclear in rice. In this study, treatments of lovastatin (an inhibitor of CK biosynthesis) and kinetin (KT; a synthetic CK) were found to inhibit rice seminal root growth in a dose-dependent manner, suggesting that endogenous CK content is optimal for rapid growth of the seminal root in rice. KT treatment strongly increased ethylene level by upregulating the transcription of ethylene biosynthesis genes. Ethylene produced in response to exogenous KT inhibited rice seminal root growth by reducing meristem size via upregulation of OsIAA3 transcription and reduced cell length by downregulating transcription of cell elongation-related genes. Moreover, the effects of KT treatment on rice seminal root growth, root meristem size and cell length were rescued by treatment with aminoethoxyvinylglycine (an inhibitor of ethylene biosynthesis), which restored ethylene level and transcription levels of OsIAA3 and cell elongation-related genes. Supraoptimal CK content increases ethylene level by promoting ethylene biosynthesis, which in turn inhibits rice seminal root growth by reducing root meristem size and cell length.