Exogenous Polyamines Research Articles

Transglutaminase 2 affinity and enzyme-substrate intermediate stability as determining factors for T-cell responses to gluten peptides in celiac disease.

The adaptive immune response of celiac disease (CeD) involves presentation of gluten peptides to CD4+ T cells by transglutaminase 2 (TG2) specific B cells. This B‐cell/T‐cell crosstalk is facilitated by involvement of TG2:gluten peptide complexes that act principally in the form of enzyme‐substrate intermediates. Here, we have addressed how gluten peptide affinity and complex stability in the presence of secondary substrates affect the uptake of TG2:gluten peptide complexes by TG2‐specific B cells and the activation of gluten‐specific T cells. We studied affinity of various gluten peptides for TG2 by biochemical assay, and monitored uptake of gluten peptides by TG2‐specific B cells by flow cytometry. Crosstalk between TG2‐specific B cells and gluten‐specific T cells was assayed with transfectants expressing antigen receptors derived from CeD patients. We found that gluten peptides with high TG2 affinity showed better uptake by TG2‐specific B cells. Uptake by B cells, and subsequent activation of T cells, was negatively affected by polyamines acting as secondary TG2 substrates. These results show that affinity between gluten peptide and TG2 governs the selection of T‐cell epitopes via enhanced uptake of TG2:gluten complexes by TG2‐specific B cells, and that exogenous polyamines can influence the CeD immune responses by disrupting TG2:gluten complexes.

Exogenous polyamines alleviate chilling injury of Citrus limon fruit

The present work investigated the alleviation of chilling injury in response to exogenous polyamines in “Eureka” lemon (Citrus limon) fruits stored at low temperature. The lemon fruits were immersed either in polyamine solutions [1 mmol/L putrescine (PUT), 1 mmol/L spermidine (SPD), or 0.5 mmol/L PUT + 0.5 mmol/L SPD (combined)] or in distilled water (control). The morphology, cellular structure (using transmission electron microscopy), chilling injury (CI) index, total soluble solids (TSS), titratable acid (TA), malondialdehyde contents, and membrane permeability, as well as the peroxidase (POD) and polyphenol oxidase (PPO) activities of the lemon fruits were measured after 0, 15, 30, and 45 days of storage at -2 ± 0.5°C. Results showed that lemon fruits treated with polyamine had higher amounts of TSS and TA, as well as POD and PPO activities. The PUT, SPD, and combined treatments exhibited significantly reduced electrolyte leakage and less evidence of chilling injury. This indicated that the synergistic effects of PUT and SPD protected the fruit from chilling injury and maintained the postharvest quality of the lemon fruits better than PUT or SPD alone did.

Polyamines in Vigna radiata (L.) Wilczek plant growth and development

Polyamines (PA) are found in all organisms. Polyamines are small aliphatic amines that have more than two amine groups. There are three main polyamines that are found in plants namely putrescine, spermidine and spermine. They can exist in both free and combined forms. In the regulation of growth, development, polyamines have regulatory roles. Polyamines also help plants in biotic and abiotic stress. Being positively charged, polyamines have the ability to interact with negatively charged sites in molecules such as nucleic acids, proteins, and lipids. Polyamines correlate with numerous vital biochemical functions, including protein regulation, regulation of chemiosmosis, and photoprotection in chloroplasts, ATP synthesis, ion channeling, and membrane fluidity. Through various studies it has been observed that exogenous PA application not only helped the plant to tolerate but also gave the plant resistance to several abiotic stresses (e.g. salinity, drought, water logging, osmotic stress, heavy metals, and extreme temperatures). Vigna radiata is native to India and is known as mung bean, mung dal, moong dal, mash bean, green gram, golden gram, and green soy. It is a major supplement of protein in vegetarian diets. Essential amino acids are present in good quantities among which Arginine, Phenylalanine, Leucine, Lysine are noteworthy. Vigna radiata is also a good source of vitamin, mineral and trace element as well as dietary fibres. Some varieties of mung bean possess excellent aroma and are called Sona mung (B1 variety). The present investigators have used the Sona mung for the study of polyamine in Vigna radiata along with other four different varieties, during the growth and development.

Metabolomics and lipidomics insight into the effect of different polyamines on tomato plants under non-stress and salinity conditions

Polyamines (PAs) are key signaling molecules involved in plant growth and stress acclimation processes. This work investigated the effect of spermidine, spermine, and putrescine (alone and in a mixture) in tomato plants using a combined metabolomics and lipidomics approach. The experiments were carried out under non-stress and 100 mM NaCl salinity conditions. Shoot and root biomass, as well as SPAD values, were increased by the application of exogenous PAs but with differences across treatments. Similarly, root length density (F: 34, p < 0.001), average root diameter (F: 14, p < 0.001), and very fine roots (0.0–0.5 mm) increased in PA-treated plants, compared to control. Metabolomics and lipidomics indicated that, despite being salinity the hierarchically prevalent factor, the different PA treatments imposed distinct remodeling at the molecular level. Plants treated with putrescine showed the broader modulation of metabolite profile, whereas spermidine and spermine induced a comparatively milder effect. The pathway analysis from differential metabolites indicated a broad and multi-level intricate modulation of several signaling molecules together with stress-related compounds like flavonoids and alkaloids. Concerning signaling processes, the complex crosstalk between phytohormones (mainly abscisic acid, cytokinins, the ethylene precursor, and jasmonates), and the membrane lipids signaling cascade (in particular, sphingolipids as well as ceramides and other glycerophospholipids), was involved in such complex response of tomato to PAs. Interestingly, PA-specific processes could be observed, with peculiar responses under either control or salinity conditions.

The Association between Spermidine/Spermine N1-Acetyltransferase (SSAT) and Human Malignancies.

Spermidine/spermine N1-acetyltransferase (SSAT) functions as a critical enzyme in maintaining the homeostasis of polyamines, including spermine, spermidine, and putrescine, in mammalian cells. SSAT is a catalytic enzyme that indirectly regulates cellular physiologies and pathways through interaction with endogenous and exogenous polyamines. Normally, SSAT exhibits only at a low cellular level, but upon tumorigenesis, the expression, protein level, and activities of SSAT are altered. The alterations induce cellular damages, including oxidative stress, cell cycle arrest, DNA dynamics, and proliferation by influencing cellular mechanisms and signaling pathways. The expression of SSAT has been reported in various studies to be altered in different cancers, and it has been correlated with tumor development and progression. Tumor grades and stages are associated with the expression levels of SSAT. SSAT can be utilized as a target for substrate binding, and excreted metabolites may be used as a novel cancer biomarker. There is also potential for SSAT to be developed as a therapeutic target. Polyamine analogs could increase SSAT expression and increase the cytotoxicity of chemotherapy to tumor cells. Drugs targeting polyamines and SSAT expression have the potential to be developed into new cancer treatments in the future.

Molecular Responses of Exogenous Polyamines under Drought Stress in the Barley Plants

Molecular Responses of Exogenous Polyamines under Drought Stress in the Barley Plants

Putrescine: A Key Metabolite Involved in Plant Development, Tolerance and Resistance Responses to Stress.

Putrescine (Put) is the starting point of the polyamines (PAs) pathway and the most common PA in higher plants. It is synthesized by two main pathways (from ornithine and arginine), but recently a third pathway from citrulline was reported in sesame plants. There is strong evidence that Put may play a crucial role not only in plant growth and development but also in the tolerance responses to the major stresses affecting crop production. The main strategies to investigate the involvement of PA in plant systems are based on the application of competitive inhibitors, exogenous PAs treatments, and the most efficient approaches based on mutant and transgenic plants. Thus, in this article, the recent advances in understanding the role of this metabolite in plant growth promotion and protection against abiotic and biotic stresses will be discussed to provide an overview for future research.

PAs Regulate Early Somatic Embryo Development by Changing the Gene Expression Level and the Hormonal Balance in Dimocarpus longan Lour.

Polyamines (PAs) play an important regulatory role in many basic cellular processes and physiological and biochemical processes. However, there are few studies on the identification of PA biosynthesis and metabolism family members and the role of PAs in the transition of plant embryogenic calli (EC) into globular embryos (GE), especially in perennial woody plants. We identified 20 genes involved in PA biosynthesis and metabolism from the third-generation genome of longan (Dimocarpus longan Lour.). There were no significant differences between longan and other species regarding the number of members, and they had high similarity with Citrus sinensis. Light, plant hormones and a variety of stress cis-acting elements were found in these family members. The biosynthesis and metabolism of PAs in longan were mainly completed by DlADC2, DlSAMDC2, DlSAMDC3, DlSPDS1A, DlSPMS, DlCuAOB, DlCuAO3A, DlPAO2 and DlPAO4B. In addition, 0.01 mmol∙L−1 1-aminocyclopropane-1-carboxylic acid (ACC), putrescine (Put) and spermine (Spm), could promote the transformation of EC into GE, and Spm treatment had the best effect, while 0.01 mmol∙L−1 D-arginine (D-arg) treatment inhibited the process. The period between the 9th and 11th days was key for the transformation of EC into GE in longan. There were higher levels of gibberellin (GA), salicylic acid (SA) and abscisic acid (ABA) and lower levels of indole-3-acetic acid (IAA), ethylene and hydrogen peroxide (H2O2) in this key period. The expression levels in this period of DlADC2, DlODC, DlSPDS1A, DlCuAOB and DlPAO4B were upregulated, while those of DlSAMDC2 and DlSPMS were downregulated. These results showed that the exogenous ACC, D-arg and PAs could regulate the transformation of EC into GE in longan by changing the content of endogenous hormones and the expression levels of PA biosynthesis and metabolism genes. This study provided a foundation for further determining the physicochemical properties and molecular evolution characteristics of the PA biosynthesis and metabolism gene families, and explored the mechanism of PAs and ethylene for regulating the transformation of plant EC into GE.

Conjugated polyamines are involved in conformation stability of plasma membrane from maturing maize grain embryos under drought stress

Polyamines are closely associated with drought stress in plants. However, the function which polyamines play in the maturing maize grain under drought is not still clear. Especially, whether the conjugated polyamines are involved in H + -ATPase activity and conformation of plasma membrane remains to be answered. Therefore, in the study, the contents of conjugated polyamines, H + -ATPase activity and conformation of plasma membrane were detected with maturing grain embryos of two maize ( Zea mays L.) cultivars, which were different in drought stress-tolerance. Under drought stress, the cell plasmolysis of the drought-sensitive Xundan No. 22 cv. was more marked than that of the drought-tolerant Yedan No. 13 cv., while the increases in the contents of conjugated non-covalently spermidine and spermine, conjugated covalently putrescine and spermidine in plasma membrane from Yedan 13 were more obvious than those in Xundan 22. The results suggested that these conjugated polyamines might be involved in stability of plasma membrane. Furthermore, H + -ATPase activity in plasma membrane from Yedan 13 increased more significantly than that in Xundan 22, indicating that these conjugated polyamines were closely correlated with the activity of H + -ATPase. To justify further the inferences, the additional experiments with exogenous spermidine, spermine and polyamine biosynthesis inhibitors were carried out in the study. The results showed that the application of exogenous spermidine or spermine increased the levels of conjugated polyamines in plasma membrane, coupled with alleviating cell plasmolysis and increasing H + -ATPase activity. The application of inhibitors decreased the levels of conjugated polyamines, coupled with aggravating cell plasmolysis and decreasing H + -ATPase activity. From these results together, it could be concluded that non-covalently conjugated spermidine and spermine, conjugated covalently putrescine and spermidine in plasma membrane functioned in increasing H + -ATPase activity, mitigating cell plasmolysis and maintaining the plasma membrane conformation of the maturing maize grain embryos under drought stress. • Drought stress increased the levels of conjugated PAs in plasma membrane. • Conjugated PAs in plasma membrane mitigated cell plasmolysis induced by drought. • Conjugated PAs enhanced the H + -ATPase activity in plasma membrane under drought. • Conjugated PAs in plasma membrane were closely associated with drought tolerance.

Conjugated Polyamines in Root Plasma Membrane Enhanced the Tolerance of Plum Seedling to Osmotic Stress by Stabilizing Membrane Structure and Therefore Elevating H+-ATPase Activity.

Polyamines are small positively charged molecules in plants and play important functions in many biological processes under various environmental stresses. One of the most confounding problems relating to polyamines (PAs) in stresses is the lack of understanding of the mechanisms underlying their function(s). Furthermore, a limited number of studies have addressed this issue at the sub-cellular level, especially in tree plants under drought stress. Therefore, in this research, by simulating natural drought stress with polyethylene glycol (PEG) osmotic stress, the relationship between the levels of conjugated polyamines and the activity of H+-ATPase in the plasma membrane was elucidated with the roots of two plum (Prunus salicina L.) cultivars, which were different in drought tolerance, as experimental materials. Furthermore, free PA levels and the activities of S-adenosylmethionine decarboxylase (SAMDC) and transglutaminase (TGase), which were closely associated with the levels of free and conjugated PAs, were also detected. Results showed that under osmotic stress, the increases of the levels of non-covalently conjugated (non-CC) spermidine (Spd) and spermine (Spm), covalently conjugated (CC) putrescine (Put) and Spd in the plasma membrane of drought-tolerant Ganli No. 5 were more significant than those of drought-sensitive Suli No. 3, indicating that these conjugated PAs might be involved in the tolerance of plum seedlings to stress. Furthermore, the conjugated PAs were closely correlated with plum seedling growth, water retention capacity, plasma membrane damage degree, and hydrogen (H+)-ATPase activity in the plasma membrane. To get more complementary pieces of evidence, we subjected plum seedlings to combined treatments of PEG and exogenous PA (Spd and Spm), and an inhibitor of SAMDC [methylglyoxal-bis (guanylhydrazone), (MGBG)] or TGase (o-phenanthroline). These results collectively suggested that non-CC Spd and Spm, CC Put and Spd in plasma membrane might function in enhancing the tolerance of plum seedlings to osmotic stress by stabilizing membrane structure and therefore elevating H+-ATPase activity.

Polyamines effectively mitigate senescence in persistent leaves of Berginia ciliata - a novel model system.

Plant leaves provide a unique insight into the changes that occur in organs, tissues and cells as they approach senescence. As part of the parental outlay, plants instigate leaf senescence to reallocate resources from older tissues to new organs towards the termination of the growing season. The aim of crop breeding initiatives is to optimize senescence for specific species. Considering hormonal regulation and their crosstalk during leaf senescence through integration of developmental signals, this work examines the efficacy of polyamines (PAs) in modulating several biochemical and physiological aspects with an ultimate aim to delay leaf senescence in leaf discs of Berginia ciliata (Haw.) sternb. Leaf discs were treated with putrescine (Put), spermidine (Spd) and spermine (Spm) at 20μM, 20μM and 15μM concentration, respectively. A set of leaf discs kept in distilled water served as the control. Leaf discs treated with PAs were green and fresh by about 4 days compared to the control, thus exhibited delayed senescence. This delayed leaf senescence corroborated with the maintenance of high activity of reactive oxygen species (ROS) scavenging antioxidant enzymes viz , superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and higher content of chlorophylls. A marked increase was also observed in membrane stability and soluble proteins in leaf discs treated with PAs. Exogenous PAs reduced oxidative stress in the leaf discs, as revealed by lower malondialdehyde (MDA) level, which is manifested as reduced lipid peroxidation (LPO). Improved membrane stability was proportional to lower LPO, as measured by the membrane stability index (MSI).

Improvement of salt tolerance in Stevia rebaudiana by co-application of endophytic fungi and exogenous spermidine

Stevia (Stevia rebaudiana Bertoni) is an important and salt-sensitive medicinal plant used as a natural sweetener in food products. In this work, we used a pot experiment to investigate the role of microbial inoculation and exogenous polyamine spermidine (Spd) in conferring salt stress tolerance in stevia by analyzing plant growth, chlorophyll (Chl) content, Chl a fluorescence, antioxidant defense system and steviol glycosides. The inoculated plants with Piriformospora indica (Pi), Tricuderma virens (Trich) or Pi+Trich were grown in optimum conditions. At the late of vegetative stage (BBCH growth stage 47), plants sprayed with different concentrations of Spd (0, 0.75, and 1.5 mM) and then were exposed to salinity stress by irrigation with saline treatments (mix of Caspian Sea and distilled water; 0, 6, and 12 dS m−1). The results revealed that salt stress increased hydrogen peroxide (H2O2) and lipid peroxidation (Malondialdehyde: MDA), and consequently plant growth characteristics and maximum photochemical quantum yield of PSII (Fv/Fm) as well as Chl content decreased, but antioxidant enzymes activity including superoxide (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) increased in the plants. Exposure to moderate salinity increased stevioside (Stv) and rebaudioside A (Reb A) content, while these compounds were decreased in the presence of severe salinity. The endophytic symbiosis and foliar spray of Spd (especially in Pi+Trich and Spd 0.75 mM) mitigated salt stress by significant increases in antioxidant enzymes activity and a decrease in H2O2 content and lipid peroxidation. Inoculation with Pi, Trich, and especially Pi+Trich increased the Chl content, Fv/Fm, shoot dry weight, and Stv and Reb A content at all salinity levels. Consequently, combined inoculation of Pi and Trich and foliar application of Spd can be a good approach to improve tolerance, growth and steviol glycosides production of stevia in salt stress conditions.

Exogenous polyamine treatment preserves postharvest quality, antioxidant compounds and reduces lipid peroxidation in black plum fruit

Black plum (Syzygium cumini L. Skeels) is a tropical and sub-tropical fruit having several medicinal properties, especially in curing diabetes. Due to non-climacteric nature, the fruit is harvested at ripe stage. However, presence of thin skin and rapid softening make the fruit highly susceptible to moisture loss and microbial attack, which drastically reduce its shelf life. Black plum, due to its high perishability cannot be stored more than 2 – 3 days at ambient conditions. In the present study, the effect of pre-storage polyamines treatment on quality and storability of black plum fruit was investigated. Ripe fruits were treated with putrescine (PUT) and spermine (SPM) each at 0.5 mM and 1.0 mM concentration by immersion method while, control fruit were treated with distilled water. The fruit were stored at ambient conditions (27 ± 3 °C, 85 ± 5% RH) for 6 days. Results revealed that 1.0 mM PUT treatment was most effective in minimizing weight loss and spoilage of about 1.5-fold compared to control. The treated fruits also retained higher anthocyanins and minimized lipid peroxidation than control. The loss of bioactive compounds like total phenolics, flavonoids, ascorbic acid and antioxidant capacity also minimized in response to polyamine treatments. The soluble solids content retained higher in 1.0 mM PUT-treated fruits but, polyamine treatments did not affect acid content. The findings of the study can be beneficially exploited in extending storability, long distant marketing and reducing postharvest loss of black plum fruit.

Responses of Polyamine-Metabolic Genes to Polyamines and Plant Stress Hormones in Arabidopsis Seedlings.

In plants, many of the enzymes in polyamine metabolism are encoded by multiple genes, whose expressions are differentially regulated under different physiological conditions. For comprehensive understanding of their regulation during the seedling growth stage, we examined the expression of polyamine metabolic genes in response to polyamines and stress-related plant hormones in Arabidopsis thaliana. While confirming previous findings such as induction of many of the genes by abscisic acid, induction of arginase genes and a copper amine oxidase gene, CuAOα3, by methyl jasmonate, that of an arginine decarboxylase gene, ADC2, and a spermine synthase gene, SPMS, by salicylic acid, and negative feedback regulation of thermospermine biosynthetic genes by thermospermine, our results showed that expressions of most of the genes are not responsive to exogenous polyamines. We thus examined expression of OsPAO6, which encodes an apoplastic polyamine oxidase and is strongly induced by polyamines in rice, by using the promoter-GUS fusion in transgenic Arabidopsis seedlings. The GUS activity was increased by treatment with methyl jasmonate but neither by polyamines nor by other plant hormones, suggesting a difference in the response to polyamines between Arabidopsis and rice. Our results provide a framework to study regulatory modules directing expression of each polyamine metabolic gene.

Polyamines Involved in Regulating Self-Incompatibility in Apple

Apple exhibits typical gametophytic self-incompatibility, in which self-S-RNase can arrest pollen tube growth, leading to failure of fertilization. To date, there have been few studies on how to resist the toxicity of self-S-RNase. In this study, pollen tube polyamines were found to respond to self-S-RNase and help pollen tubes defend against self-S-RNase. In particular, the contents of putrescine, spermidine, and spermine in the pollen tube treated with self-S-RNase were substantially lower than those treated with non-self-S-RNase. Further analysis of gene expression of key enzymes in the synthesis and degradation pathways of polyamines found that the expression of DIAMINE OXIDASE 4 (MdDAO4) as well as several polyamine oxidases such as POLYAMINE OXIDASES 3 (MdPAO3), POLYAMINE OXIDASES 4 (MdPAO4), and POLYAMINE OXIDASES 6 (MdPAO6) were significantly up-regulated under self-S-RNase treatment, resulting in the reduction of polyamines. Silencing MdPAO6 in pollen tubes alleviates the inhibitory effect of self-S-RNase on pollen tube growth. In addition, exogenous polyamines also enhance pollen tube resistance to self-S-RNase. Transcriptome sequencing data found that polyamines may communicate with S-RNase through the calcium signal pathway, thereby regulating the growth of the pollen tubes. To summarize, our results suggested that polyamines responded to the self-incompatibility reaction and could enhance pollen tube tolerance to S-RNase, thus providing a potential way to break self-incompatibility in apple.

Polyamines Upregulate Cephalosporin C Production and Expression of β-Lactam Biosynthetic Genes in High-Yielding Acremonium chrysogenum Strain.

The high-yielding production of pharmaceutically significant secondary metabolites in filamentous fungi is obtained by random mutagenesis; such changes may be associated with shifts in the metabolism of polyamines. We have previously shown that, in the Acremonium chrysogenum cephalosporin C high-yielding strain (HY), the content of endogenous polyamines increased by four- to five-fold. Other studies have shown that the addition of exogenous polyamines can increase the production of target secondary metabolites in highly active fungal producers, in particular, increase the biosynthesis of β-lactams in the Penicillium chrysogenum Wis 54–1255 strain, an improved producer of penicillin G. In the current study, we demonstrate that the introduction of exogenous polyamines, such as spermidine or 1,3-diaminopropane, to A. chrysogenum wild-type (WT) and HY strains, leads to an increase in colony germination and morphological changes in a complete agar medium. The addition of 5 mM polyamines during fermentation increases the production of cephalosporin C in the A. chrysogenum HY strain by 15–20% and upregulates genes belonging to the beta-lactam biosynthetic cluster. The data obtained indicate the intersection of the metabolisms of polyamines and beta-lactams in A. chrysogenum and are important for the construction of improved producers of secondary metabolites in filamentous fungi.

Polyamine Metabolism under Different Light Regimes in Wheat.

Although the relationship between polyamines and photosynthesis has been investigated at several levels, the main aim of this experiment was to test light-intensity-dependent influence of polyamine metabolism with or without exogenous polyamines. First, the effect of the duration of the daily illumination, then the effects of different light intensities (50, 250, and 500 μmol m–2 s–1) on the polyamine metabolism at metabolite and gene expression levels were investigated. In the second experiment, polyamine treatments, namely putrescine, spermidine and spermine, were also applied. The different light quantities induced different changes in the polyamine metabolism. In the leaves, light distinctly induced the putrescine level and reduced the 1,3-diaminopropane content. Leaves and roots responded differently to the polyamine treatments. Polyamines improved photosynthesis under lower light conditions. Exogenous polyamine treatments influenced the polyamine metabolism differently under individual light regimes. The fine-tuning of the synthesis, back-conversion and terminal catabolism could be responsible for the observed different polyamine metabolism-modulating strategies, leading to successful adaptation to different light conditions.

Analysis of the expression of polyamine biosynthesis genes in nodules of the garden pea (Pisum sativum L.) and the effect of exogenous treatment with polyamines on their development

BACKGROUND: Polyamines are acting as signaling molecules during adaptation to stressful environment and as regulators of plant development. In plants, polyamines are represented mainly by putrescine, spermidine and spermine. The concentration of polyamines in symbiotic nodules of some legumes is 510 times higher than in the other organs, which indicates their important role in the formation and functioning of symbiotic nodules.&#x0D; MATERIALS AND METHODS: We analyzed the expression of genes encoding polyamine biosynthesis enzymes in symbiotic nodules, as well as the effect of exogenous polyamines on the nodule number and the average nodule weight in wild-type SGE plants and symbiotic pea mutants SGEFix-1 (sym40-1) and SGEFix-2 (sym33-3).&#x0D; RESULTS: The comparable expression level of arginine decarboxylase gene (PsADC) was observed in all analyzed nodules, whereas the expression level of ornithine decarboxylase gene (PsODC), was highly increased in nodules of SGEFix-2 (sym33-3) mutant. Treatment of the root system with a 0.1 mM solution of polyamines mixture led to an increase in the average weight of the nodule in wild-type plants and in the SGEFix-2 (sym33-3) mutant plants.&#x0D; CONCLUSIONS: It was shown that the main pathway of putrescine synthesis in wild-type pea symbiotic nodules is the arginine pathway, while the ornithine pathway is probably associated with activation of plant defense reactions. Polyamines acting, apparently, through ethylene, affect the functioning of the nodule meristem.

An in vitro model for studies of attenuation of antibiotic-inhibited growth of Aggregatibacter actinomycetemcomitans Y4 by polyamines.

Polyamines are ubiquitous polycationic molecules that are present in all prokaryotic and eukaryotic cells, and they serve as important modulators of cell growth, stress, and cell proliferation. Polyamines are present at high concentrations in the periodontal pocket and could potentially affect the stress response of periodontal bacteria to antibiotics. The effects of polyamines on inhibition of growth by amoxicillin (AMX), azithromycin (AZM), and doxycycline (DOX) were investigated with the Y4 strain of Aggregatibacter actinomycetemcomitans (Aa). Bacteria were grown in brain heart infusion broth under the following conditions: (1) Aa only, (2) Aa + polyamine mix (1 mM putrescine, 0.4 mM spermidine, and 0.4 mM spermine), (3) Aa + antibiotic, and (4) Aa + antibiotic + polyamines. Growth curve analysis, minimal inhibitory concentration determination, and transcriptomic studies were conducted. The presence of exogenous polyamines produced a small, but significant increase in Aa growth, and polyamines attenuated the inhibitory effects of AMX, AZM, and DOX on growth. Transcriptomic analysis revealed that polyamines upregulate expression of ribosomal biogenesis proteins and small subunits, attenuate the bacterial stress response to antibiotics, and modulate bacterial nutritional pathways in a manner that could potentially increase the virulence of Aa. In summary, the polyamine‐rich environment found in periodontal pockets appears to protect Aa and reduce its susceptibility to several antimicrobial agents in this in vitro model.

Exogenous Polyamines Influence In Vitro Microbial Adhesion to Human Mucus According to the Age of Mucus Donor.

Adhesion to intestinal mucus is the first step for microbiota colonization in early life. Polyamines are polycations with important physiological functions in both procaryotic and eucaryotic cells. However, their role in intestinal mucus adhesion is not known. The objective of the present study was to evaluate whether exogenous polyamines (putrescine, spermidine, spermine, and their combination) would alter the adhesive properties of Lacticaseibacillus rhamnosus GG (LGG), Bifidobacterium animalis subs. lactis Bb12, Cronobacter sakazakii, and Escherichia coli. Human intestinal mucus was isolated from healthy infants (0–6-month-old and 6–12-month-old) and healthy adults (25–52 years old). Spermidine significantly increased Bb12 adhesion (p < 0.05) in the mucus of infants (0–6 months) but reduced the adhesion of LGG in adult mucus (p < 0.05) with no significant effect in any of the infant groups. Spermine was more effective than polyamine combinations in reducing C. sakazakii (p < 0.05) adhesion in early infant mucus (0–6 months). The adhesion ability of E. coli remained unaffected by exogenous polyamines at any age in the concentrations tested. Our data suggest that polyamines may modulate the bacterial adhesion to mucus depending on the bacterial strain and depending at what age the mucus has been generated.