Endogenous polyamine profiles in different tissues of <Emphasis Type="Italic">Coffea</Emphasis> sp., and their levels during the ontogeny of fruits

Polyamines are essential compounds for growth and development in plants. An attempt has been made to find out the endogenous polyamine profiles in various parts and during the ontogeny of fruit formation of two commercially important Coffea species viz., arabica and canephora. Putrescine (Put), spermine (Spm) and spermidine (Spd) are the predominant polyamines during the ontogeny of fruit and their level increased with the advancement of fruit development. However, in the initial stages of flower and fruit development Spm levels were found to be decreased. Elevated levels of major polyamines Put, Spd, and Spm were observed in zygotic embryos than in somatic embryos. Along with this cadavarine (Cad) and other biogenic amines viz., tyramine (Tyr) and tryptamine (Try) were also found during the ontogeny of fruit in C. canephora. In this study the enodogenous polyamine profiles in coffee tissues and beans have been addressed.     

Polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine (Pinus virginiana Mill.) plantlets

Polyamines have been demonstrated to play an important role in adventitious root formation and development in plants. Here, we present a detailed analysis of influence of exogenously added polyamines on adventitious root development and its relationship to cold tolerance in Virginia pine (Pinus virginia Mill.). Our results demonstrated that polyamines putrescine (Put), spermidine (Spd), and spermine (Spm) at 0.001 mM improve rooting frequency and promote root elongation. Put, Spd, and Spm at 0.01–1 mM decrease rooting frequency and reduce root elongation root elongation. Measurements of diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.4.3.4) activities showed that higher DAO and PAO enzyme activities were obtained when high concentrations of polyamines were applied and when plantlets were treated for 5–7 week at 4°C and 16°C. Survival rate of plantlets increased with the treatment of polyamines at low temperature. Polyamines increased mitotic index of cells in root tips of regenerated plantlet cultured on medium containing 0.001 μM Put, Spd, or Spm, but did not increase mitotic index in tissues of needle tips of the same plantlets. These results demonstrated that polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine plantlets.     

Polyamine and nitric oxide levels relate with morphogenetic evolution in somatic embryogenesis of <Emphasis Type="Italic">Ocotea catharinensis</Emphasis>

In this study we examined the effect of polyamines (PAs) putrescine (Put), spermidine (Spd) and spermine (Spm) on growth, morphology evolution, endogenous PAs levels and nitric oxide (NO) release in Ocotea catharinensis somatic embryo cultures. We observed that Spd and Spm reduced culture growth, permitted embryo morphogenetic evolution from the earliest to last embryo development stages, increased endogenous PAs levels, and induced NO release in O. catharinensis somatic embryos. On the other hand, Put had little effect on these parameters. Spd and Spm could successfully be used to promote somatic embryo maturation in O. catharinensis. The results suggest that Spd and Spm have an important role during the growth, development and morphogenetic evolution of somatic embryos, through alterations in the endogenous nitric oxide and PAs metabolism in this species.     

A polyamine metabolon involving aminopropyl transferase complexes in Arabidopsis

The conversion of putrescine to spermidine in the biosynthetic pathway of plant polyamines is catalyzed by two closely related spermidine synthases, SPDS1 and SPDS2, in Arabidopsis. In the yeast two-hybrid system, SPDS2 was found to interact with SPDS1 and a novel protein, SPMS (spermine synthase), which is homologous with SPDS2 and SPDS1. SPMS interacts with both SPDS1 and SPDS2 in yeast and in vitro. Unlike SPDS1 and SPDS2, SPMS failed to suppress the speDelta3 deficiency of spermidine synthase in yeast. However, SPMS was able to complement the speDelta4 spermine deficiency in yeast, indicating that SPMS is a novel spermine synthase. The SPDS and SPMS proteins showed no homodimerization but formed heterodimers in vitro. Pairwise coexpression of hemagglutinin- and c-Myc epitope-labeled proteins in Arabidopsis cells confirmed the existence of coimmunoprecipitating SPDS1-SPDS2 and SDPS2-SPMS heterodimers in vivo. The epitope-labeled SPDS and SPMS proteins copurified with protein complexes ranging in size from 650 to 750 kD. Our data demonstrate the existence of a metabolon involving at least the last two steps of polyamine biosynthesis in Arabidopsis.     

Changes in free polyamine titers and expression of polyamine biosynthetic genes during growth of peach <Emphasis Type="Italic">in vitro</Emphasis> callus

In the present paper, correlation between free polyamines and growth of peach (Prunus persica cv. Yuzora) in vitro callus was investigated. Growth of the callus was divided into three phases based on measurement of fresh weight. Free polyamines, putrescine (Put), spermidine (Spd), and spermine (Spm), could be detected during peach callus growth. Changes in free Put titers followed the callus growth rate, as shown by low and stable levels in the first stage, quick increase at the beginning of the second phase, and slow increase in the last phase, whereas fluctuations of Spd and Spm titers were aberrant from that of Put at early stage. Expressions of five key genes involved in polyamine biosynthesis were characterized, in which only the genes leading to Put synthesis, ADC (arginine decarboxylase) and ODC (ornithine decarboxylase), agreed with callus growth and fluctuation of Put titers. Treatment of the callus with D-arginine, an inhibitor of ADC, led to significant growth inhibition and enormous reduction of endogenous Put, coupled with obvious decrease of mRNA levels of ADC and ODC. Exogenous application of Put partially restored the callus growth, along with resumption of endogenous Put and expression levels of ADC and ODC. Spd and Spm titers experienced minor change in comparison to Put. The data presented here suggested that free Put played an important part in peach callus growth. Putative mechanisms or mode of action underlying the role of Put in peach callus growth and different expression patterns of the genes responsible for polyamine biosynthesis are also discussed.     

Polyamines in the photosynthetic apparatus

The three main polyamines putrescine (Put), spermidine (Spd) and spermine (Spm) were characterized by HPLC in intact spinach leaf cells, intact chloroplasts, thylakoid membranes, Photosystem II membranes, the light-harvesting complex and the PS II complex. All contain the three polyamines in various ratios; the HPLC polyamine profiles of highly resolved PS II species (a Photosystem II core and the rection center) suggest an enrichment in the polyamine Spm.Abbreviations Chl chlorophyll - HPLC high performance liquid chromatography - LHC light-harvesting complex - PS II Photosystem II - PS II-RC Photosystem II reaction center - Put putrescine - Spd spermidine - Spm spermine - 10%S-core D₁-D₂-Cyt b559-47 kD-43 kD complex     

Exogenous polyamines enhance copper tolerance of Nymphoides peltatum

The protective effects of polyamines (PAs) against copper (Cu) toxicity were investigated in the leaves of Nymphoides peltatum. Cu treatment increased the putrescine (Put) level and lowered spermidine (Spd) and spermine (Spm) levels, thereby reducing the (Spd+Spm)/Put ratio in leaves. Exogenous application of Spd or Spm markedly reversed these Cu-induced effects for all three PAs and partially restored the (Spd+Spm)/Put ratio in leaves. It also significantly enhanced the level of proline, retarded the loss of soluble protein, decreased the rate of O2*- generation and H2O2 content, and prevented Cu-induced lipid peroxidation. Furthermore, exogenous Spd and Spm reduced the accumulation of Cu and effectively maintained the balance of nutrient elements in plant leaves under Cu stress. These results suggest that exogenous application of Spd or Spm can enhance the tolerance of N. peltatum to Cu by increasing the levels of endogenous Spd and Spm as well as the (Spd+Spm)/Put ratio.     

Long term exogenous putrescine application improves grain yield of a salt-sensitive rice cultivar exposed to NaCl

In order to determine the impact of polyamines on the yield-related parameters of rice (Oryza sativa L.) exposed to NaCl, the plants belonging to a salt-sensitive cultivar I Kong Pao were maintained from the young seedling stage until harvest on nutrient solutions containing 0 or 30 mM NaCl in the presence or absence of 10 μM putrescine (Put), 10 μM spermidine (Spd) or 10 μM spermine (Spm). Exogenous Put and to a lesser extent exogenous Spd improved growth and yield of salt-treated plants in relation to an increase in K⁺/Na⁺ ratio of shoots and roots as compared to plants exposed to NaCl in the absence of exogenous polyamines. Exogenous Put also improved the net CO₂ assimilation, at least partly as a consequence of an increase in the stomatal conductance. Yield increase of salt-treated plants exposed to Put was related to an improvement of floral morphogenesis leading to a higher number of fertile tillers per plant and a higher number of spikelets per panicle. Putrescine also improved the pollen viability in salt-treated plants, allowing a higher seed set and thus a higher grain yield per plant. Although polyamines accumulated in the shoots to some extent in response to exogenous application, neither Put nor Spd accumulated in the seeds. In contrast, Spm did not afford any protection of salt-treated plants but was translocated to the seeds during maturation. Seeds with a high internal Spm concentration exhibited delayed germination in the presence of NaCl. These data are discussed in relation to the implication of polyamine in the metabolism and physiology of salt-treated plants.     

Stimulating effect of spermine on bulblet formation in bulb-scale segments of Lilium longiflorum

When bulb-scale segments of Lilium longiflorum were cultured on a medium containing auxin and cytokinin, the proportion of the expiants with newly-formed bulblets was significantly increased by the application of different polyamines. The most effective polyamine was spermine, where more than 90% of segments formed an average of 5 bulblets as compared to controls where less than 50% explants formed an average of 1.5 bulblets. Application of arginine one of the precursors putrescine biosynthesis, slightly promoted bulblet formation. The putrescine-stimulated bulblet formation was strongly inhibited by simultaneous addition of an inhibitor of the spermidine synthase, cyclohexylamine. The spermidine-promoted bulblet formation, however, could not be suppressed by this inhibitor. The promotive effect of spermidine on bulblet formation was reversed by an inhibitor of the spermine synthase, N-(3-aminopropyl)cyclohexylamine, but application of this inhibitor with spermine did not show any apparent effect on the bulblet formation. Endogenous level of spermine increased in common during bulblet formation that were stimulated by exogenous polyamines. Thus, spermine seemed to be the main stimulating chemical on bulblet formation in lily bulb-scale segments.Abbreviations APCHA N-(3-aminopropyl)cyclohexylamine - Arg arginine - BA benzyladenine - CHA cyclohexylamine - MS Murashige and Skoog's - NAA naphthaleneacetic acid - Orn ornithine - Put putrescine - Spd spermidine - Spm spermine     

Association of polyamines in governing the chilling sensitivity of maize genotypes

Chilling stress is an important constraint of global production of maize. This study was undertaken to compare the chilling responses of different maize seedling tissues and to analyze changes in polyamines as a result of chilling stress. Reponses to chilling were characterized in two maize (Zea mays L.) inbred lines, ‘HuangC’ and ‘Mo17’, that putatively differ in chilling sensitivity. Seedlings were exposed to low temperature (5°C) and chilling injury was estimated by electrical conductivity (EC), malonaldehyde (MDA) concentration, and by changes in putrescine (Put), spermidine (Spd) and spermine (Spm) concentrations in root, mesocotyl, and coleoptile tissues. Membrane permeability (as measured by EC), MDA concentrations and Put concentrations in the three tissue of maize seedlings increased after chilling stress, except for the Put concentration in roots. Spd and Spm concentrations in the three tissues of seedlings decreased after chilling stress. The EC for cold stressed tissues were lower in HuangC than Mo17. Also, the EC of coleoptile tissues were lower than for mesocotyl in both inbred lines. We suggest that mesocotyl tissue can be used to evaluate cold tolerance in maize. Stepwise regression analyses showed that chilling injury in roots was generally correlated with Spd concentration while in the mesocotyl injury was mainly correlated with Put and Spd concentrations. Spermidine and Spm concentrations in the coleoptile were correlated with chilling injury. Characteristics changes of polyamines in chill-tolerant maize seedling combined with regression analysis are a reliable method for evaluating chill tolerance in maize lines.     

‘神马’菊花花芽分化与内源多胺的关系

用薄层层析-荧光法测定菊花'神马'花芽分化期间顶芽和叶片中多胺的动态变化,分析了菊花花芽分化与多胺的关系.结果表明,花芽分化起始期顶芽中的腐胺(Put)含量急剧下降,此后在低水平上波动;叶片内Put则于总苞鳞片分化初期大幅上升,其后各阶段处于较低的水平.顶芽中精胺(Spm)与亚精胺(Spd)含量呈平行波动上升趋势,顶芽中Spin在小花原基分化初期直到花冠分化中期处于优势地位,而顶芽中Spd并无明显变化.顶芽、叶片中的Spin变化趋势相反,顶芽中Spm、Spd的含量变化趋势十分相似,但叶片中却呈交替性变化.结果显示,菊花花芽分化过程中,Put含量的降低有利于启动菊花花芽分化,后期Spm的增加有利于小花的分化,叶片可能向顶芽提供Spm,顶芽和叶片中的Spd与小花原基分化有密切关系.     

Involvement of polyamines in the post-anthesis development of inferior and superior spikelets in rice

Early-flowered superior spikelets usually exhibit a faster grain filling rate and heavier grain weight than late-flowered inferior spikelets in rice (Oryza sativa L.). But the intrinsic factors responsible for the variations between the two types of spikelets are unclear. This study investigated whether and how polyamines (PAs) are involved in regulating post-anthesis development of rice spikelets. Six rice genotypes differing in grain filling rate were field grown, and PA levels and activities of the enzymes involved in PA biosynthesis were measured in both superior and inferior spikelets. The results showed that superior spikelets exhibited higher levels of free spermidine (Spd) and free spermine (Spm) and higher activities of arginine decarboxylase (ADC, EC 4.1.1.19), S-adenosylmethionine decarboxylase (SAMDC, EC 4.1.1.50) and Spd synthase (EC 2.5.1.16) than inferior spikelets at the early endosperm cell division and grain filling stage. The maximum concentrations of free Spd and free Spm and the maximum activities of ADC, SAMDC and Spd synthase were significantly correlated with the maximum cell division and grain filling rates, maximum cell number and grain weight. Application of Spd and Spm to panicles resulted in significantly higher rates of endosperm cell division and grain filling in inferior spikelets along with the activities of sucrose synthase (EC 2.4.1.13), ADP glucose pyrophosphorylase (EC 2.7.7.27) and soluble starch synthase (EC 2.4.1.21), suggesting that these PAs are involved in the sucrose-starch metabolic pathway. The results indicate that the poor development of inferior spikelets is attributed, at least partly, to the low PA level and its low biosynthetic activity.     

Improved Al tolerance of saffron (Crocus sativus L.) by exogenous polyamines

The aluminum (Al) tolerance of saffron (Crocus sativus L.) in hydroponics and the method of improving Al tolerance were investigated. Compared with the Al-free control, saffron root elongation was decreased by 59.3 and 75% at 0.05 and 0.2 mM Al stress, respectively. At 0.5 mM Al stress, the root elongation was inhibited completely. Addition of 1 mM polyamines improved saffron root growth markedly at 0.2 mM Al stress. Putrescine (Put) showed better amelioration effect than spermidine (Spd) and spermine (Spm). The root elongation in Put treatment was only 15% lower than that of Al-free control. The alleviation of Al rhizotoxicity by polyamines might be attributed to lower Al content in the root tips, and subsequent less lipid peroxidation and oxidative stress. Higher activities of amine oxidases and Hydrogen peroxide (H₂O₂) content might decrease the effects of Spd and Spm on alleviating oxidative damage compared with that of Put.     

Effect of exogenous spermidine on polyamine metabolism in water hyacinth leaves under mercury stress

The influence of exogenous spermidine (Spd) on arginine decarboxylase (ADC), ornithine decarboxylase (ODC), polyamine oxidase (PAO) activities and polyamines (PAs), proline contents in water hyacinth leaves under Mercury (Hg) stress was investigated after 6 days treatment. The results showed that free putrescine (Put) content increased, the contents of free spermidine (Spd) and spermine (Spm) and the (Spd + Spm)/Put ratio in water hyacinth leaves decreased significantly with the increase of the Hg concentrations. Hg stress also disturbed the activities of ADC, ODC and PAO and caused changes on proline content. Compared to the Hg-treatment only, exogenous Spd (0.1 mM) significantly reduced the accumulation of free Put, increased the contents of free Spd and Spm and the ratio of (Spd + Spm)/Put in water hyacinth leaves. Furthermore, exogenous Spd enhanced the activities of ADC, ODC and PAO and significantly increased proline content. The PS-conjugated PAs and PIS-bound PAs changed in the same trend as free PAs. These results suggest that exogenous Spd can alleviate the metabolic disturbance of polyamines caused by Hg in water hyacinth leaves.     

Polyamines and cellular metabolism in plants: transgenic approaches reveal different responses to diamine putrescine versus higher polyamines spermidine and spermine

Distribution of biogenic amines—the diamine putrescine (Put), triamine spermidine (Spd), and tetraamine spermine (Spm)—differs between species with Put and Spd being particularly abundant and Spm the least abundant in plant cells. These amines are important for cell viability and their intracellular levels are tightly regulated, which have made it difficult to characterize individual effects of Put, Spd and Spm on plant growth and developmental processes. The recent transgenic intervention and mutational genetics have made it possible to stably alter levels of naturally occurring polyamines and study their biological effects. We bring together an analysis of certain metabolic changes, particularly in amino acids, to infer the responsive regulation brought about by increased diamine or polyamine levels in actively growing poplar cell cultures (transformed with mouse ornithine decarboxylase gene to accumulate high Put levels) and ripening tomato pericarp (transformed with yeast S-adenosylmethionine decarboxylase gene to accumulate high Spd and Spm levels at the cost of Put). Our analysis indicates that increased Put has little effect on increasing the levels of Spd and Spm, while Spd and Spm levels are inter-dependent. Further, Put levels were positively associated with Ala (α and β), Ile and GABA and negatively correlated with Gln and Glu in both actively growing poplar cell cultures and non-dividing tomato pericarp tissue. Most amino acids showed positive correlations with Spd and Spm levels in actively growing cells. Collectively these results suggest that Put is a negative regulator while Spd–Spm are positive regulators of cellular amino acid metabolism.     

Involvement of polyamines in the drought resistance of rice

This study investigated whether and how polyamines (PAs) in rice (Oryza sativa L.) plants are involved in drought resistance. Six rice cultivars differing in drought resistance were used and subjected to well-watered and water-stressed treatments during their reproductive period. The activities of arginine decarboxylase, S-adenosyl-L-methionine decarboxylase, and spermidine (Spd) synthase in the leaves were significantly enhanced by water stress, in good agreement with the increase in putrescine (Put), Spd, and spermine (Spm) contents there. The increased contents of free Spd, free Spm, and insoluble-conjugated Put under water stress were significantly correlated with the yield maintenance ratio (the ratio of grain yield under water-stressed conditions to grain yield under well-watered conditions) of the cultivars. Free Put at an early stage of water stress positively, whereas at a later stage negatively, correlated with the yield maintenance ratio. No significant differences were observed in soluble-conjugated PAs and insoluble-conjugated Spd and Spm among the cultivars. Free PAs showed significant accumulation when leaf water potentials reached -0.51 MPa to -0.62 MPa for the drought-resistant cultivars and -0.70 MPa to -0.84 MPa for the drought-susceptible ones. The results suggest that rice has a large capacity to enhance PA biosynthesis in leaves in response to water stress. The role of PAs in plant defence to water stress varies with PA forms and stress stages. In adapting to drought it would be good for rice to have the physiological traits of higher levels of free Spd/free Spm and insoluble-conjugated Put, as well as early accumulation of free PAs, under water stress.     

Effect of NaCl and Polyamines on Plasma Membrane Lipids of Wheat Roots

Caryopses of a salt sensitive wheat cultivar (Triticum aestivum L. cv. Giza 163) were presoaked in 2.5 mM putrescine (Put), 5 mM spermidine (Spd) or 2.5 mM spermine (Spm) for 24 h and then subjected to 150 mM NaCl added to the growth medium for 15 d. Effects of NaCl and polyamines (PAs) on plasma membrane (PM) lipids, phospholipids, fatty acids, and free sterols were determined. NaCl treatment caused a decrease in total phospholipids, increase in saturated fatty acids and altered distribution of sterols and phospholipids. NaCl also induced increase in sterol/phospholipid ratio. PAs treatments (particularly Put and Spd) counterbalanced the NaCl deleterious effects on PM lipids.     

Spermidine biosynthesis as affected by osmotic stress in oat leaves

A new assay for the evaluation of spermidine (Spd) synthase activity was developed. It involves a coupled reaction and avoids the use of decarboxylated S-adenosylmethionine, which is unstable and not easily available. This assay was applied to assess changes in enzyme activity in oat leaves subjected to osmotic stress in the dark. The results indicate that osmotically-induced putrescine (Put) accumulation in cereals results not only from the activation of the arginine decarboxylase pathway, but also from the inhibition of the activity of Spd synthase, the enzyme which catalyzes the transformation of Put to Spd. Other possibilities which could contribute to the decline of Spd and spermine levels under osmotic stress are also discussed.Abbreviations ADC arginine decarboxylase - Dap diaminopropane - DFMA -difluoromethylarginine - MGBG methylglyoxal-bis-guanylhydrazone - MTA 5-deoxy-5-methylthioadenosine - ODC ornithine decarboxylase - PA polyamines - PAO polyamine oxidase - PCA perchloric acid - PLP pyridoxal phosphate - Put putrescine - SAM S-adenosylmethionine - dSAM decarboxylated S-adenosylmethionine - SAMDC S-adenosylmethionine decarboxylase - Spd spermidine - Spm spermine