Endogenous Polyamine Levels Research Articles

Putrescine Biosynthesis and Oxidation in Normal and Hairy Root Tobacco Plants

The enzymes involved in putrescine synthesis and oxidation were studied in transformed tobacco plants micropropagated in vitro and arising from Agrobacterium rhizogenes inoculation. They showed different degrees of phenotypic alterations, particularly evident in supertransformed plants. Diamine oxidase activity in the leaves was generally higher in transformed and even more in supertransformed plants than in controls. Arginine and ornithine decarboxylase activities, determined in both apices and leaves, were in agreement with data on endogenous polyamine levels in apices, but not in the leaves. This was probably due to a different compartmentation of enzymes, substrates and products.

Putrescine extends effective pollination period in ‘Comice’ pear ( Pyrus communis L.) irrespective of post-anthesis ethylene levels

Putrescine (PUT) 10 −3 M, a polyamine applied at bloom, enhanced pollen tube ovule penetration and delayed ovule senescence, extending the effective pollination period of cultivar ‘Comice’ pear ( Pyrus communis L.) by at least 2 days and 4 days in 1985 and 1986, respectively, without reducing post-pollination flower ethylene levels. Evolved flower ethylene peaked at pollination and again at petal senescence in vivo while vacuum-extracted ethylene peaked only during fertilization. Endogenous polyamine levels were not related to ethylene levels during the post-bloom period in any flowers. After pollination, putrescine-treated flowers exhibited lower levels of evolving ethylene than untreated flowers. Hand-pollinated flowers had greater polyamine levels than unpollinated. Putrescine-treated flowers had lower endogenous polyamine levels and higher nitrogen contents than untreated flowers. Earlier pollen tube penetration, delayed ovule longevity and extended ‘Comice’ effective pollination period from a PUT application were not associated with reduced post-anthesis, ethylene levels.

Senescence of Rice Leaves XXXII. Effects of Abscisic Acid and Benzyladenine on Polyamines and Ethylene Production during Senescence

Summary The effects of abscisic acid (ABA) and benzyladenine (BA) on polyamines and ethylene production during senescence of detached rice leaves under light were investigated. The senescence of rice leaves was followed by measuring the decrease of protein. BA (0.01 mM) significantly retarded and ABA (0.1 mM) markedly promoted senescence of detached rice leaves. Putrescine and spermine levels were increased (30 to 50 %) by ABA and decreased (30 to 50 %) by BA. However, spermidine level was found to be decreased (50 %) by ABA and increased (25 %) by BA. BA treatment had no effect on the activities of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC, but resulted in 20 to 50 % lower activity of arginine decarboxylase (ADC) when compared with the water controls. Both the activities of ODC and SAMDC were increased about 2–3 times by ABA during the 3rd and 4th day of incubation. ABA treatment resulted in a peak of ADC activity during the first 24 h of incubation. ABA inhibited but BA promoted ethylene production during senescence. It is concluded that (a) endogenous polyamine levels and polyamine biosynthetic enzyme activities are not correlated with rice leaf senescence, (b) the effect of ABA of BA on senescence are separated from that on polyamine levels or polyamine biosynthesis, and (c) polyamine and ethylene biosynthesis in rice leaves do not compete for the substrate, S-adenosylmethionine.

Senescence of rice leaves XXXI. Changes of chlorophyll, protein, and polyamine contents and ethylene production during senescence of a chlorophyll-deficient mutant

Leaf senescence of a chlorophylldeficient rice mutant (LT-8) was investigated. At 10 days after planting, the chlorophyll level in the third leaves of rice seedlings of the mutant was about one half that of normal leaves (Norin no. 8), whereas no difference in the protein level could be detected in the two genotypes. The protein level in leaves decreased with increasing age, and no significant difference could be detected during senescence in the two genotypes. Chlorophyll level in the normal leaves also decreased with increasing age. However, the chlorophyll level in the mutant leaves began to decrease only after more than 60% of the initial protein had been degraded. The pattern of ethylene production in the normal leaves was, in general, similar to that in the mutant leaves. Ethylene production first decreased with age, increased to a maximum at day 18, and decreased thereafter. Both spermidine and spermine levels in the leaves of the two genotypes decreased with increasing age. The pattern of the putrescine level in the normal leaves behaved somewhat similar to that in the mutant leaves. However, during the course of senescence, the putrescine level in the mutant leaves was always higher than that in the normal leaves. The possible relationship between endogenous polyamine levels and ethylene production is discussed.

Senescence of Rice Leaves XXX Levels of Endogenous Polyamines and Dark-Induced Senescence of Rice Leaves

The role of endogenous polyamines in the control of dark-induced senescence of detached rice leaves was investigated by quantitating levels of various polyamines by HPLC. Putrescine, spermidine and spermine were all present throughout senescence. Neither cadaverine nor 1,3diaminopropane was detected. During dark-induced senescence, there was a marked decrease in levels of putrescine and an increase in those of spermidine and spermine. The rate of production of ethylene increased markedly upon excision of leaves. a-Difluoromethylarginine (DFMA) and a-difluoromethylornithine (DFMO) caused a reduction in levels of putrescine, yet had no effect on levels of spermidine and spermine. Neither DFMA nor DFMO had any effect on senescence or on the production of ethylene. Treatment with dicyclohexylamine (DCH) and methylglyoxal Ws-(guanylhydrazone) (MGBG) reduced levels of spermine and increased those of putrescine in detached leaves. After treatment with DCH or MGBG, both senescence and the production of ethylene were significantly promoted. The current results suggest that endogenous polyamines may not play a significant role in the control of dark-induced senescence of rice leaves. This conclusion is supported by the further observations that (a) benzyladenine, which is known to retard senescence, decreased levels of putrescine but had no effect on those of spermidine and spermine; and (b) ABA, which promoted senescence, increased levels of putrescine and had no effect on those of spermidine and spermine.

Differential sensitivity of various human tumors to inhibition of poly amine biosynthesis in vivo

Polyamines are essential for normal and neoplastic growth. Ornithine decarboxylase (ODC) is the first and rate-limiting enzyme in the polyamine biosynthetic pathway. alpha-Difluoromethylornithine (DFMO) is an enzyme-activated irreversible inhibitor of ODC, and a known anti-neoplastic agent. The purpose of this study was to examine the susceptibility of various human cancers to inhibition by DFMO in vivo. We have studied three human pancreatic adenocarcinomas, designated CAV, SKI, and PGER, two human colon adenocarcinomas (LS-180 and WIDR), and three metastatic cell lines of a human gastric adenocarcinoma (BHM, BMM, BLM) that were growing in congenitally athymic (nude) Balb/c mice. Mice bearing each tumor were divided into two groups; one group served as controls and the other group received DFMO 3% in drinking water. Tumor growth and weight, and content of DNA, RNA, protein and polyamines were determined and correlated. DFMO significantly inhibited the growth of three of the three gastric tumors, two of the three pancreatic tumors and neither of the two colon tumors. The tumor content of DNA, RNA and protein exhibited a pattern that was parallel to tumor growth. The tumor polyamine concentration did not correlate with sensitivity to DFMO. These findings provide clear evidence for important differences in the sensitivity of various human cancers to growth inhibition by DFMO and indicate that endogenous polyamine levels alone do not predict the sensitivity of the tumors to DFMO.

Polyamines and ethylene in the removal of embryonal dormancy in apple seeds

Putrescine (Put), spermidine (Spd) and spermine (Spm) were found in seeds of apple (Malus domestica Borkh. cv. Antonovka), in amounts that increased in the order given. The levels slowly decreased during 30 days of stratification. Exogenous polyamines (PAs) affected germination of isolated embryos in a way dependent on the type of polyamine, its concentration, and the state of the embryo dormancy. The effect of Put and Spd on germination was stimulatory, while that of Spm was inhibitory. Stimulation of germination was also observed when embryos were treated with arginine, ornithine and methionine. Canavanine inhibited germination, and this effect was reversed by arginine or Put. Ethephon, aminooxyacetic acid (AOA) and aminoethoxyvinylglycine (AVG) present during seed stratification had no effect on the levels of endogenous PAs. Put and Spd did not change ethylene production, neither during seed stratification nor during embryo germination, whereas Spm reduced ethylene evolution. The data suggest that Spm plays a role in the maintenance of dormancy by preventing ethylene production, while Put and Spd participate in dormancy removal, independently of ethylene.

Senescence of rice leaves XXIX. Ethylene production, polyamine level and polyamine biosynthetic enzyme activity during senescence

Changes of ethylene production, polyamine level and activities of enzymes related of polyamine biosynthesis during senescence of intact leaves of rice ( Oryza sativa L.) seedlings were investigated. Ethylene production decreased markedly at the early stage of senescence, but increased slightly at the later stage. Putrescine, spermidine and spermine, but not cadaverine and diaminopropane, were present in rice leaves throughout senescence. The spermine level decreased progressively with increasing age. The putrescine and spermidine levels as well as arginine decarboxylase activity decreased at the early stage of senescence and increased at the later stage. The increase of ornithine decarboxylase and S-adenosylmethionine decarboxylase activities occurred at the time when leaves were fully expanded and at an advanced stage of senescence. These data seem to support the view that polyamines play an important role in the regulation of rice senescence. Results also suggest that endogenous polyamine levels and ethylene production may not be interrelated during senescence of rice leaves.

Polyamines as Modulators of Salt Tolerance in Rice Cultivars

The effect of NaCl on the endogenous levels of diamine, putrescine and polyamines, spermidine and spermine, was studied in the shoot system of salt-tolerant and salt-sensitive lines of rice (Oryza sativa L.) cultivars during three growth stages. Salt stress increased the levels of diamine and polyamine in varying degrees among nine rice cultivars investigated. Salt tolerant AU1, Co43, and CSC1 were effective in maintaining high concentrations of spermidine and spermine, while the content of putrescine was not significantly altered in all the growth stages when plants were exposed to salinity. The salt sensitivity in rice was associated with excessive accumulation of putrescine and with low levels of spermidine and spermine in the shoot system of salt-sensitive cultivars Co36, CSC2, GR3, IR20, TKM4, and TKM9 under saline condition. One of the possible mechanisms of saline resistance was observed to be due to the highly increased polyamines against the low increase in diamines. Alternatively, the salt sensitivity could be due to high increase of diamines and an incapacity to maintain high levels of polyamines.

Protein synthesis in polyamine-deficient bacteria during amino-acid starvation

Amino-acid starvation in polyamine-auxotrophic bacteria grown in the presence of putrescine provokes a marked inhibition of protein synthesis. This inhibition is almost completely relieved in polyamine-depleted cells. The differential behaviour of bacterial protein synthesis depending on the endogenous levels of polyamines is not due to a change in the uptake of amino acids used to measure protein synthesis, nor to the decreased growth rate of polyamine-depleted cells. During leucine starvation, cells grown with putrescine synthesized a somewhat lower amount of high-molecular-weight proteins than polyamine-depleted bacteria. In addition, cells with normal endogenous levels of polyamines accumulated significant amounts of 62 and 41 kDa polypeptides as well as several low-molecular-weight peptides.

Polyamines as growth substances in higher plants.

Aliphatic polyamines, recently recognized as a new class of plant growth substances or plant hormones (Bagni et al., 1982), are present in all the plants examined to date and mainly act on cell division processes. However, as other well-known plant hormones (auxins, cytokinins, gibberellins, but also abscisic acid and ethylene), they display a broad spectrum of effects on plant tissues, but very little is understood of the underlying events and processes. In spite of the wide variety of responses, the tendency is to generalize from observations made on a single type of response. We propose, therefore, to examine some of the characteristics of polyamines especially in relation to their role as plant growth substances. The early studies showed that in a plant tissue, temporarily lacking in polyamines, a positive effect on the induction of cell division was demonstrated by supplying exogenous polyamines (Bertossi et al., 1965), while in plants with a normal polyamine level this positive effect could not be recognized. Anyway a direct correlation between endogenous polyamine levels and growth rate was shown in normal and tumour plant tissues (Bagni and Serafini-Fracassini, 1979 and 1985). In the absence of plant mutants deficient in the enzymes responsible for putrescine synthesis, contrary to those isolated in microorganisms (Tabor and Tabor, 1983; Tabor et al., 1983) and animals (Pohjanpelto et al., 1981; Steglich et al., 1983), the approach used until a few years ago was to study the mechanisms of polyamine-induced plant growth by utilizing different competitive and irreversible inhibitors of polyamine synthesis.

Changes of polyamines and ethylene in cucumber seedlings in response to chilling stress

Cucumber (Cucumis sativus L. cv. Victory) seedlings were exposed to chilling at 5°C and endogenous levels of polyamines and 1‐aminocyclopropane‐1‐carboxylic acid (ACC) were measured after chilling and after warming at 20°C. The level of spermidine was higher in the chilled seedlings than in the non‐chilled seedlings. Treatment with a plant bioregulator, (2RS,3RS)‐1‐(4‐cholorophenyl)‐4,4‐dimethyl‐2‐(1,2,4‐triazol‐1‐yl)pentan‐3‐ol (paclobutrazol), reduced the chilling injury and the levels of spermidine in the chilled seedlings. The levels of ACC and production of ethylene showed sharp increases after warming following exposure to chilling. These increases were suppressed by the application of aminooxyacetic acid (AOA). However, AOA treatment did not reduce chilling injury or affect the levels of polyamines in the tissue. These data indicate that the increase in ACC and ethylene is a response of the tissue to the chilling exposure and is not a cause of the injury. The data also suggest that the syntheses of polyamines and ethylene are not competitive with each other even under chilling stress conditions.

Ornithine and arginine decarboxylases and polyamine involvement during in vivo differentiation and in vitro dedifferentiation of Datura innoxia leaf explants

The effects of exogenous ornithine, arginine and polyamines added to media leading to root, callus or bud initiation of Datura innoxia Mill. leaf explants growing in vitro were examined. Ornithine and arginine decarboxylase activities (ODC, EC 4.1.1.17; ADC, EC 4.1.1.19) as well as endogenous polyamine levels were also determined during the course of in vivo differentiation of the leaves and their subsequent in vitro dedifferentiation under rooting, callusing, or budding conditions. Decarboxylase activities were determined by measuring the 14CO2 released and the polyamines were quantified after dansylation by thin‐layer chromatography. In vivo, ODC and ADC activities decreased from shoots to young to old leaves. In vitro, synergistic effects between ornithine and indole‐3‐acetic acid on rhizogenesis were detected, while arginine was not effective. Exogenous putrescine also acted synergistically with auxin by promoting root growth. A close relationship was found between rhizogenesis, ODC activity and increase in endogenous putrescine and spermidine levels. ODC increased during the induction and time course of cell dedifferentiation and seemed to support these events, while ADC seemed to support only the later events involving redifferentiation.

Automated chromatographic analysis of human placenta polyamines

The levels of endogenous polyamines were quantified in human placenta at different stages of fetal development by an automated chromatographic technique. The appearance around the sixth month of pregnancy of an unidentified basic compound was observed.