Polyamine Content Research Articles

Deletion of the Bcnrps1 Gene Increases the Pathogenicity of Botrytis cinerea and Reduces Its Tolerance to the Exogenous Toxic Substances Spermidine and Pyrimethanil.

During the infection of grapevine (Vitis vinifera) by the fungus Botrytis cinerea, the concentration of polyamines, which are toxic substances for the phytopathogen, increases in the grape. Nine NRPS genes have been identified in the genome of B. cinerea, yet the function of five of them remains unknown. For this reason, we have studied the expression of the 9 NRPS genes by RT-qPCR in a medium supplemented with sublethal concentrations of three polyamines (1,3-diaminopropane (1,3-DAP), spermidine (SPD), and spermine (SPM)). Our results show that the presence of polyamines in the culture medium triggered the overexpression of the Bcnrps1 gene in the pathogen. Deleting Bcnrps1 did not affect mycelial growth or adaptation to osmotic stress, and we show that its expression is not essential for the cycle of infection of the B. cinerea. However, mutating the Bcnrps1 gene resulted in overexpression of the Bcnrps6 gene, which encodes for the excretion of siderophores of the coprogen family. Moreover, gene deletion has reduced the tolerance of B. cinerea B05.10 to toxic substances such as the polyamine SPD and the fungicide pyrimethanil, and its virulence has increased. Our findings provide new insights into the function of the Bcnrps1 gene and its involvement in the tolerance of B. cinerea against exogenous toxic compounds.

Ecometabolomics of plant–herbivore and plant–fungi interactions: a synthesis study

AbstractThe functional adaptive responses of higher plants to biotic interactions with herbivores and fungi have long been topics of research. One constraint to obtaining a comprehensive understanding of the most general plant responses, however, has been the difficulty of studying all plant functional shifts simultaneously due to analytical limitations. Now this is possible with the advent of metabolomics. Using 151 records from the WEB of SCIENCE database, we have analyzed the development and application of metabolomic profiles to ecological studies in the last two decades. We have used meta‐analysis and pathway enrichment analyses to assess the whole set of constitutive and inducible defenses. Constitutive defenses against herbivores were mainly based on a significant high level of the metabolism of several amino acids with parallel increases in the concentrations of flavones (phenolics) and saponins (glycosides). Inducible defenses, though, were mainly based on the increases in concentration of methyl‐ketone, pantothenate, and Coenzyme A. Butyrate metabolism and the mitochondrial electron‐transport chain were upregulated, in agreement with previous reports that herbivory‐activated plant chemical defenses were mainly based on jasmonic acid, salicylic acid, and ethylene‐associated pathways. The metabolic responses/acclimations to pathogenic fungi were mainly linked with increases in aspartate and pyruvate metabolism, the transfer of acetyl groups within mitochondria, and the upregulation of branched‐chain amino acids degradation pathways. These responses/acclimations were accompanied by higher concentrations of the most important groups of secondary metabolites such as phenolics (anthocyanins, flavonoids), quinones, alkaloids, terpenoids, and polyamines and other compounds related to antistress mechanisms such as proline. The leaves of mycorrhized plants accumulated nucleotide sugars, sphingolipids, and methylhistidine. These responses were associated with maintaining the integrity of plant cell membranes under fungal hypha penetration. The responses were accompanied by increases in the concentrations of phenolics, blumenols, and alkaloids and decreases in the concentrations of polyamines, consistent with the mycorrhizal inhibition of polyamines. This summary provides a clear synthesis of the most successful plant strategies selected after millions of years of evolution and will be a very promising tool for the management of crops and ecosystems and for selecting the main lines in breeding studies for future research.

Influence of Breastfeeding Factors on Polyamine Content in Human Milk.

The polyamine content of human breast milk, which is the first exogenous source of polyamines for the newborn, can be affected by several factors associated with the mother, the infant, or breastfeeding itself. The aim of this study was to evaluate the influence of different breastfeeding factors on the polyamines found in human milk. For this study, a cohort of 83 mothers was considered for up to 4 months, and a subgroup of 33 mothers were followed during the first six months of breastfeeding. Two breast milk samples were collected at each sampling point (foremilk and hindmilk) and the polyamine content was determined by UHPLC-FL. Polyamine levels varied considerably between the mothers and tended to decrease over time. Putrescine was the minor polyamine, whereas spermidine and spermine contents were very similar. The concentrations of the three polyamines were significantly higher in hindmilk than foremilk (p < 0.001). Spermidine and spermine levels decreased significantly through the lactation progress (p < 0.05). Finally, slightly higher levels of polyamines were observed in the milk of mothers providing partial, rather than full, breastfeeding, although the differences were not significant. The polyamine content in human milk was found to change during a single feed (foremilk versus hindmilk) and as lactation progressed, mainly in response to the specific circumstances of the newborn.

Genome-wide identification and expression analysis of Polyamine Uptake Transporter gene family in sweet orange (Citrus sinensis).

Polyamine uptake transporter (PUT) plays important roles in polyamine homeostasis, but knowledge regarding PUT family genes in sweet orange (Citrus sinensis) remains elusive. Herein, our study aimed to perform a genome-wide identification of the PUT gene family in C. sinensis. A total of eight putative PUT genes (CsPUT1-CsPUT8) were identified in the sweet orange genome and distributed on three chromosomes. The CsPUT genes were divided into two major groups according to the phylogenetic tree analysis, with high similarities in protein domains and gene structure organization. The CsPUT genes were differentially expressed in different tissues, with the highest transcript levels being in the flowers and roots. Interestingly, the CsPUT genes were significantly induced by polyamines, putrescine, spermidine and spermine, indicating that CsPUT were possibly associated with intracellular polyamine transport and uptake. In addition, CsPUT showed differential expression in callus treated with ABA, cold, salt or osmotic shock. CsPUT4 was selected as a candidate for functional analysis of PUT. Overexpression of CsPUT4 elevated endogenous polyamine content and led to enhanced cold tolerance in transgenic callus cultures. Overall, these data provide valuable information for better understanding the potential biological functions of PUT genes in future.

Rice aquaporin OsPIP2;2 is a water-transporting facilitator in relevance to drought-tolerant responses.

In rice (Oryza sativa), the PLASMA MEMBRANE INTRINSIC PROTEIN (PIP) family of aquaporin has 11 members, OsPIP1;1 to OsPIP1;3, and OsPIP2;1 to OsPIP2;8, which are hypothesized to facilitate the transport of H2O and other small compounds across cell membranes. To date, however, only OsPIP1;2, OsPIP2;1, and OsPIP2;4 have been demonstrated for substrate selectivity in their source plant (rice). In this study, OsPIP2;2 was characterized as the most efficient facilitator of H2O transport across cell membranes in comparison with the other 10 OsPIPs. In concomitant tests of all OsPIPs, four genes (OsPIP1;3, OsPIP2;1, OsPIP2;2, and OsPIP2;4) were induced to express in leaves of rice plants following a physiological drought stress, while OsPIP2;2 was expressed to the highest level. After de novo expression in frog oocytes and yeast cells, the four OsPIP proteins were localized to the plasma membranes in trimer and tetramer and displayed the activity to increase the membrane permeability to H2O. In comparison, OsPIP2;2 was most supportive to H2O import to oocytes and yeast cells. After de novo expression in tobacco protoplasts, OsPIP2;2 exceeded OsPIP1;3, OsPIP2;1, and OsPIP2;4 to support H2O transport across the plasma membranes. OsPIP2;2‐mediated H2O transport was accompanied by drought‐tolerant responses, including increases in concentrations of proline and polyamines, both of which are physiological markers of drought tolerance. In rice protoplasts, H2O transport and drought‐tolerant responses, which included expression of marker genes of drought tolerance pathway, were considerably enhanced by OsPIP2;2 overexpression but strongly inhibited by the gene silencing. Furthermore, OsPIP2;2 played a role in maintenance of the cell membrane integrity and effectively protected rice cells from electrolyte leakage caused by the physiological drought stress. These results suggest that OsPIP2;2 is a predominant facilitator of H2O transport in relevance to drought tolerance in the plant.

Spermidine Pretreatments Mitigate the Effects of Saline Stress by Improving Growth and Saline Excretion in Frankenia pulverulenta

Climatic change, ecosystem imbalance, and soil salinization and desertification are serious obstacles to the restoration of degraded landscapes. Halophyte cultivation could constitute a way of mitigating these problems. Frankenia pulverulenta is used in the remediation and revegetation of areas affected by salinity and as an ornamental plant on saline soils since it can tolerate salt concentrations up to 200 mM NaCl. To increase saline tolerance, different plant growth regulators (auxins, cytokinins, gibberellins, spermidine, and salicylic acid) were tested in hydroponic conditions before the addition of NaCl (300 mM). At 52 days, growth, proline, saline excretion, free polyamines, and ethylene were determined under both saline and non-saline conditions. All growth regulators improved growth in the salt-free pretreatment; however, under conditions of salinity, pretreatment with spermidine (0.5 mM) and then salicylic acid (0.5 mM) were efficient at reversing the inhibitory effect of salt and improved saline excretion in F. pulverulenta. A strong positive correlation of polyamines and proline, and a negative correlation with ethylene, indicate that pretreatments that increase endogenous polyamine content and osmolytes are the most effective in improving salt tolerance of F. pulverulenta and could be used in the technical guidance of the cultivation of this halophyte.

Occurrence of Polyamines in Foods and the Influence of Cooking Processes.

Dietary polyamines are involved in different aspects of human health and play an important role in the prevention of certain chronic conditions such as cardiovascular diseases and diabetes. Different polyamines can be found in all foods in variable amounts. Moreover, several culinary practices have been reported to modify the content and profile of these bioactive compounds in food although experimental data are still scarce and even contradictory. Therefore, the aim of this study was to evaluate the occurrence of polyamines in a large range of foods and to assess the effect of different cooking processes on the polyamine content of a few of them. The highest level of polyamines was found in wheat germ (440.6 mg/kg). Among foods of a plant origin, high levels of total polyamines over 90 mg/kg were determined in mushrooms, green peppers, peas, citrus fruit, broad beans and tempeh with spermidine being predominant (ranging from 54 to 109 mg/kg). In foods of an animal origin, the highest levels of polyamines, above all putrescine (42–130 mg/kg), were found in raw milk, hard and blue cheeses and in dry-fermented sausages. Regarding the influence of different domestic cooking processes, polyamine levels in food were reduced by up to 64% by boiling and grilling but remained practically unmodified by microwave and sous-vide cooking.

Synaptic Scaffolds, Ion Channels and Polyamines in Mouse Photoreceptor Synapses: Anatomy of a Signaling Complex.

Synaptic signaling complexes are held together by scaffold proteins, each of which is selectively capable of interacting with a number of other proteins. In previous studies of rabbit retina, we found Synapse-Associated Protein-102 (SAP102) and Channel Associated Protein of Synapse-110 (Chapsyn110) selectively localized in the tips of horizontal cell processes at contacts with rod and cone photoreceptors, along with several interacting ion channels. We have examined the equivalent suites of proteins in mouse retina and found similarities and differences. In the mouse retina we identified Chapsyn110 as the scaffold selectively localized in the tips of horizontal cells contacting photoreceptors, with Sap102 more diffusely present. As in rabbit, the inward rectifier potassium channel Kir2.1 was present with Chapsyn110 on the tips of horizontal cell dendrites within photoreceptor invaginations, where it could provide a hyperpolarization-activated current that could contribute to ephaptic signaling in the photoreceptor synapses. Pannexin 1 and Pannexin 2, thought to play a role in ephaptic and/or pH mediated signaling, were present in the outer plexiform layer, but likely not in the horizontal cells. Polyamines regulate many ion channels and control the degree of rectification of Kir2.1 by imposing a voltage-dependent block. During the day polyamine immunolabeling was unexpectedly high in photoreceptor terminals compared to other areas of the retina. This content was significantly lower at night, when polyamine content was predominantly in Müller glia, indicating daily rhythms of polyamine content. Both rod and cone terminals displayed the same rhythm. While polyamine content was not prominent in horizontal cells, if polyamines are released, they may regulate the activity of Kir2.1 channels located in the tips of HCs. The rhythmic change in polyamine content of photoreceptor terminals suggests that a daily rhythm tunes the behavior of suites of ion channels within the photoreceptor synapses.

In Vitro Reconstitution of Yeast Translation System Capable of Synthesizing Long Polypeptide and Recapitulating Programmed Ribosome Stalling.

The rates of translation elongation or termination in eukaryotes are modulated through cooperative molecular interactions involving mRNA, the ribosome, aminoacyl- and nascent polypeptidyl-tRNAs, and translation factors. To investigate the molecular mechanisms underlying these processes, we developed an in vitro translation system from yeast, reconstituted with purified translation elongation and termination factors, utilizing CrPV IGR IRES-containing mRNA, which functions in the absence of initiation factors. The system is capable of synthesizing not only short oligopeptides but also long reporter proteins such as nanoluciferase. By setting appropriate translation reaction conditions, such as the Mg2+/polyamine concentration, the arrest of translation elongation by known ribosome-stalling sequences (e.g., polyproline and CGA codon repeats) is properly recapitulated in this system. We describe protocols for the preparation of the system components, manipulation of the system, and detection of the translation products. We also mention critical parameters for setting up the translation reaction conditions. This reconstituted translation system not only facilitates biochemical analyses of translation but is also useful for various applications, such as structural and functional studies with the aim of designing drugs that act on eukaryotic ribosomes, and the development of systems for producing novel functional proteins by incorporating unnatural amino acids by eukaryotic ribosomes.

Polyamine-producing bacterium Bacillus megaterium N3 reduced Cd accumulation in wheat and increased the expression of DNA repair- and plant hormone- related proteins in wheat roots

Metal-immobilizing bacteria play an important role in reducing the metal uptake of plants. However, little research has characterized the effects of polyamine-producing bacteria on the inhibition of Cd uptake in wheat. Herein, the effects of Bacillus megaterium N3 on wheat Cd uptake and the differentially expressed proteins in wheat roots were studied using hydroponic experiments. The results showed that under 3 mg L-1 Cd stress, strain N3 reduced the Cd content in wheat roots (33.59%) and leaves (82.83%) compared with no inoculation. Strain N3 significantly reduced (24.19%-31.02%) the proportion of Cd in the organelles and the soluble fraction and increased (74.91%) the proportion of Cd in the cell walls of wheat roots. Moreover, the contents of abscisic acid and polyamines in the wheat roots and leaves also increased (22.64%-372.8%) in the presence of strain N3 under 3 mg L-1 Cd. Label-free proteomics showed that 127 and 85 proteins were up- and downregulated in the N3+Cd treatment compared with the Cd treatment. The significantly enriched items were identified as a protein-DNA complex, DNA packaging complex, intercellular transport, peroxidase activity, and transferase activity. Moreover, the expression of DNA replication, plant hormone, and Fe-Zn transporter related proteins in wheat roots was increased in the presence of strain N3 compared with uninoculated roots under Cd stress. These results provide new insights and a theoretical basis for applying polyamine-producing bacteria to safe wheat production.

Polyamines: Functions, Metabolism, and Role in Human Disease Management.

Putrescine, spermine, and spermidine are the important polyamines (PAs), found in all living organisms. PAs are formed by the decarboxylation of amino acids, and they facilitate cell growth and development via different cellular responses. PAs are the integrated part of the cellular and genetic metabolism and help in transcription, translation, signaling, and post-translational modifications. At the cellular level, PA concentration may influence the condition of various diseases in the body. For instance, a high PA level is detrimental to patients suffering from aging, cognitive impairment, and cancer. The levels of PAs decline with age in humans, which is associated with different health disorders. On the other hand, PAs reduce the risk of many cardiovascular diseases and increase longevity, when taken in an optimum quantity. Therefore, a controlled diet is an easy way to maintain the level of PAs in the body. Based on the nutritional intake of PAs, healthy cell functioning can be maintained. Moreover, several diseases can also be controlled to a higher extend via maintaining the metabolism of PAs. The present review discusses the types, important functions, and metabolism of PAs in humans. It also highlights the nutritional role of PAs in the prevention of various diseases.

Industrial and culinary practice effects on biologically active polyamines level in turkey meat

Polyamines, including putrescine, spermidine, and spermine, are biological compounds present in nearly all food items. Their desirable physiological effects include cell division and growth. Hence, are undesirable in the diet of patients with tumor. This study aimed to assess the impact of curing agents (sodium chloride (0–2 g), sodium nitrite (0–200 ppm), sodium polyphosphate (0–0.5 g), and ascorbic acid (0–500 ppm)), cooking (frying (180°C), and boiling (100°C)) on polyamine contents in turkey breast meat using response surface methodology based on central composite design and dispersive liquid-liquid microextraction. Postprocessing changes were investigated using a high-performance liquid chromatography equipped with an ultraviolet detector. Study outcomes showed the presence of sodium chloride, sodium nitrite, and sodium polyphosphate in turkey meat reduced the putrescine and spermine content significantly (P &lt; 0.0001). The addition of ascorbic acid as a curing agent slightly increased the concentration of polyamines, while no significant linear effects were associated with the thermal processes. The study observed that curing agents like sodium chloride, sodium nitrite, sodium polyphosphate, and ascorbic acid at 2 g, 200 ppm, 0.5 g, and 382 ppm, respectively, in frying mode minimized spermine and putrescine content with more than 96% desirability. In conclusion, curing additives and cooking are promising procedures for polyamine reduction in turkey breast meat.

Silicon augments salt tolerance through modulation of polyamine and GABA metabolism in two indica rice (Oryza sativa L.) cultivars

Polyamines (PA) have multifarious roles in plant-environment interaction and stress responses. In conjunction with GABA shunt, they regulate induction of tolerance under salinity stress in plants. Here, we tested the hypothesis that silicon improves salt tolerance through mediating vital metabolic pathways rather than acting as a mere mechanical barrier. Seedlings of two rice (Oryza sativa L.) cultivars MTU 1010 (salt-sensitive) & Nonabokra (salt-tolerant) growing in hydroponic culture were treated with NaCl (0, 25, 50 & 100 mM) combined with or without Si (2 mM). NaCl stress enhanced PA synthesizing enzymes activity and PA production in salt tolerant cultivar Nonabokra, whereas in the sensitive cultivar, MTU 1010 both declined. Enhanced activities of GABA synthesizing enzymes along with a decline in the activities of GABA degrading enzymes under NaCl exposure led to GABA accumulation in both the cultivars. The interactive effects of silicon and NaCl also induced the activities of the enzymes related to polyamine biosynthesis and inhibited polyamine degrading enzymes that enhanced PA contents in the cultivars. Supplemental Si decreased endogenous GABA levels by modulating GABA metabolising enzymes under NaCl stress. On the basis of all tested parameters cv. MTU 1010 was proven to be more responsive towards silicon application than cv. Nonabokra. Such study of silicon-induced polyamine accretion and reduced GABA accumulation may lower oxidative damage in rice cultivars under NaCl stress and thereby form a successful strategy to boost tolerance.

Overexpression of the white clover TrSAMDC1 gene enhanced salt and drought resistance in Arabidopsis thaliana

S-adenosylmethionine decarboxylase (SAMDC) mediates the biosynthesis of polyamines (PAs) and plays a positive role in plants’ response to adversity stress tolerance. In this study, we isolated a SAMDC gene from white clover, which is located in mitochondria. It was strongly induced when white clover exposed to drought (15% PEG6000), salinity (200 mM NaCl), 20 μM spermidine, 100 μM abscisic acid, and 10 mM H2O2, especially in leaves. The INVSc1 yeast introduced with TrSAMDC1 had tolerance to drought, salt, and oxidative stress. Overexpression of TrSAMDC1 in Arabidopsis showed higher fresh weight and dry weight under drought and salt treatment and without growth inhibition under normal conditions. Leaf senescence induced by drought and saline was further delayed in transgenic plants, regardless of cultivation in 1/2 MS medium and soil. During drought and salt stress, transgenic plants exhibited a significant increase in relative water content, maximum photosynthesis efficiency (Fv/Fm), performance index on the absorption basis (PIABS), activities of antioxidant protective enzymes such as SOD, POD, CAT, and APX, and a significant decrease in accumulation of MDA and H2O2 as compared to the WT. The concentrations of total PAs, putrescine, spermidine, and spermidine in transgenic lines were higher in transgenic plants than in WT under normal and drought conditions. These results suggested that TrSAMDC1 could effectively mitigate abiotic stresses without the expense of production and be a potential candidate gene for improving the drought and salt resistance of crops.

Foliar application of polyamines improve some morphological and physiological characteristics of rose

Abstract Objective This experiment was conducted to investigate the effects of foliar spray of polyamines on some morphological and physiological characteristics of rose. Materials and methods Experimental variants involved the type (putrescine, spermidine and spermine) and concentration (0 mM, 1 mM, 2 mM and 4 mM) of polyamines. In this research, the plant height, number of leaves and shoots, leaf area and thickness, fresh and dry weight of leaf and stem, the content of anthocyanin, soluble sugar, phenol and antioxidant capacity were measured 2 weeks after the end of experiment. Results Results indicated that among all polyamine types, putrescine has the highest effect on the morphological characteristics. Among different concentrations of polyamines, the concentration of 1 mM resulted in the highest increase in shoot fresh and dry weight. Putrescine application at 2 mM and 4 mM concentrations increased soluble sugar content. In the present study, polyamine treatment reduced the content of anthocyanin, phenol and antioxidant capacity. Conclusions It can be cocluded that application of polyamines improved some morphological and physiological traits in various ways.

Characterising the Response of Human Breast Cancer Cells to Polyamine Modulation.

Breast cancer is a complex heterogeneous disease with multiple underlying causes. The polyamines putrescine, spermidine, and spermine are polycationic molecules essential for cell proliferation. Their biosynthesis is upregulated in breast cancer and they contribute to disease progression. While elevated polyamines are linked to breast cancer cell proliferation, there is little evidence to suggest breast cancer cells of different hormone receptor status are equally dependent on polyamines. In this study, we characterized the responses of two breast cancer cells, ER+ (oestrogen receptor positive) MCF-7 and ER- MDA-MB-231 cell lines, to polyamine modulation and determined the requirement of each polyamine for cancer cell growth. The cells were exposed to DFMO (a polyamine pathway inhibitor) at various concentrations under different conditions, after which several growth parameters were determined. Exposure of both cell lines to DFMO induced differential growth responses, MCF-7 cells showed greater sensitivity to polyamine pathway inhibition at various DFMO concentrations than the MDA-MB-231 cells. Analysis of intracellular DFMO after withdrawal from growth medium showed residual DFMO in the cells with concomitant decreases in polyamine content, ODC protein level, and cell growth. Addition of exogenous polyamines reversed the cell growth inhibition, and this growth recovery appears to be partly dependent on the spermidine content of the cell. Similarly, DFMO exposure inhibits the global translation state of the cells, with spermidine addition reversing the inhibition of translation in the breast cancer cells. Taken together, these data suggest that breast cancer cells are differentially sensitive to the antitumour effects of polyamine depletion, thus, targeting polyamine metabolism might be therapeutically beneficial in breast cancer management based on their subtype.

Exogenous melatonin alleviated chilling injury in harvested plum fruit via affecting the levels of polyamines conjugated to plasma membrane

Polyamines (PAs) are related closely with many abiotic stresses. However, conjugated PA functions are not clear in alleviating chilling injury in fruit. The contents of free PAs in plum flesh cell and conjugated PAs in plasma membrane (PM), the activities of S-adenosylmethionine decarboxylase (SAMDC) and transglutaminase (TGase), and the degree of chilling injury were investigated in harvested plum (Prunus salicina L.) fruit pre-treated with exogenous melatonin. Chilling treatment resulted in the injury of plasma membrane (PM), as judged by the increased PM permeability, chilling injury index and malondialdehyde (MDA) content, and the decreased sulfhydryl group contents. Exogenous melatonin alleviated chilling injury, in parallel with the increased levels of free spermidine (Spd) and spermine (Spm) in cell, conjugated non-covalently (CNC) Spd and Spm, and conjugated covalently (CC) Put and Spd in PM, resulting from the increased activities of SAMDC and TGase. The results of the additional experiments with two inhibitors, methylglyoxyl-bis (guanylhydrazone) (MGBG) and phenanthrolin, which inhibit the activities of SAMDC and TGase, respectively, were complementary evidences for our research. MGBG and TGase treatment decreased the level of CNC PAs (Spd and Spm) and CC PAs (Put and Spd), respectively, coupled with aggravating the chilling injury. From these above mentioned-results, it could be suggested that exogenous melatonin alleviated chilling injury by elevating the levels of CNC Spd, CNC Spm, CC Put and CC Spd in PM.

Impact of nicotine pathway downregulation on polyamine biosynthesis and leaf ripening in tobacco.

Traditional breeding and molecular approaches have been used to develop tobacco varieties with reduced nicotine and secondary alkaloid levels. However, available low‐alkaloid tobacco varieties have impaired leaf quality likely due to the metabolic consequences of nicotine biosynthesis downregulation. Recently, we found evidence that the unbalanced crosstalk between nicotine and polyamine pathways is involved in impaired leaf ripening of a low‐alkaloid (LA) Burley 21 line having a mutation at the Nic1 and Nic2 loci, key biosynthetic regulators of nicotine biosynthesis. Since the Nic1 and Nic2 loci are comprised of several genes, all phenotypic changes seen in LA Burley 21 could be due to a mixture of genetics‐based responses. Here, we investigated the commercial burley variety TN90 LC and its transgenic versions with only one downregulated gene, either putrescine methyl transferase (PMT‐RNAi) or PR50‐protein (PR50‐RNAi). Nicotine levels of cured lamina of TN90 LC, TN90 PMT‐RNAi and TN90 PR50‐RNAi, were 70.5 ± 3.8, 2.4 ± 0.5, and 6.0 ± 1.1 mg/g dry weight, respectively. Low‐alkaloid transgenic lines showed delayed leaf maturation and impaired leaf quality. We analyzed polyamine contents and ripening markers in wild‐type TN90 control plants (WT) and the two transgenic lines. The ripening markers revealed that the PMT‐RNAi line showed the most pronounced impaired leaf maturation phenotype at harvest, characterized by higher chlorophyll (19%) and glucose (173%) contents and more leaf mesophyll cells per area (25%), while the ripening markers revealed that maturation of PR50‐RNAi plants was intermediate between PMT‐RNAi and WT lines. Comparative polyamine analyses showed an increase in free and conjugated polyamines in roots of both transgenic lines, this being most pronounced in the PMT‐RNAi plants. For PMT‐RNAi plants, there were further perturbations of polyamine content in the leaves, which mirrored the general phenotype, as PR50‐RNAi transgenic plants looked more similar to the WT than PMT‐RNAi transgenic plants. Activity of ornithine decarboxylase, the enzyme that catalyzes the committing step of polyamine biosynthesis, was significantly higher in roots and mature leaves of PMT‐RNAi plants in comparison to WT, while there was no increase observed for arginine decarboxylase. Treatment of both transgenic lines with polyamine biosynthesis inhibitors decreased the polyamine content and ameliorated the phenotype, confirming the intricate interplay of polyamine and nicotine biosynthesis in tobacco and the influence of this interplay on leaf ripening.

Polyamines of biological fluids of the body and the diagnostic value of their determination in clinical and laboratory researches (review of literature).

The review provides the analysis of the content of the main polyamines (PA) - spermine, spermidine and putrescine in the most important biological fluids of the human body (blood, urine, seminal fluid, etc.). The assessment of their diagnostic and prognostic value in clinical practice is carried out. The novelty and value of assessing of the level of PA metabolites as new diagnostic markers of various diseases has been shown. Among such diseases as cancer, stroke, renal failure, for which the search for early markers is especially relevant. This survey data can be of practical interest and taken into account in estimating the level of PA and its derivatives in clinical and laboratory reseaches. The literature search for the review was carried out using the Scopus, Web of Science, MedLine, RSCI databases.

Polyamine treatment ameliorates pericarp browning in cold-stored ‘Nanguo’ pears by protecting mitochondrial structure and function

Refrigeration is the most common way to store ‘Nanguo’ pears. However, their pericarps are prone to browning during the shelf life after refrigeration. In this study, we examined the effects of polyamines (PAs) on pericarp browning and analyzed their impact on mitochondrial morphology and function. Exogenous PAs substantially alleviated the onset and development of pericarp browning in pear fruit treated with them. PA content and the expression and activity of anabolic enzymes related to PAs increased, whereas the reactive oxygen species levels decreased. Moreover, the PA treatment preserved pericarp mitochondrial structure. Exogenous PA diminished the rate of increase and amplitude of mitochondrial membrane permeability transition pore opening and mitochondrial membrane permeability. To a certain extent, the PA treatment maintained mitochondrial energy levels. These results imply that exogenous PA treatment may be a strategy for ameliorating the browning of cold stored ‘Nanguo’ pears.