Effect of polyamines on adventitious root formation from Tobacco (Nicotiana tabaccum) leaf segments

To elucidate the effect of polyamines on adventitious root formation, we investigated the relationship between the frequency of adventitious root formation and the endogenous content of free polyamines in tobacco leaf segments which had been treated with polyamine biosynthesis inhibitors and polyamines. Adventitious root formation was inhibited in rooting medium (10 μM IAA) with methylglyoxal-bis(guanylhydrazone) (MGBG) or cyclohexylamine (CHA), and promoted with spermidine and putrescine. Treatment with high IAA (100 μM) medium plus CHA or MGBG promoted rooting up reversion of the rooting inhibition than the one treated with high IAA concentration alone. Spermidine promoted adventitious root numbers on low IAA (1 μM) medium when applied during culture period. The rooting inductive phase (in the presence of IAA) was determined by periodical transfer of leaf segments from IAA-containing medium to IAA free medium, and by changing polyamine contents, to be inductive phase. Putrescine and spermidine were accumulated to a maximum during the inductive phase. Therefore, the results point out the involvement of polyamines in inductive phase of adventitious root formation in tobacco leaf segments.     

Involvement of polyamines in the adventitious rooting of micropropagated shoots of the apple rootstock MM106

Apple rootstock MM106 shoots, raised in vitro, rooted at 96.7% after culture on a medium supplemented with an auxin for 5 d in darkness followed by culture on a second medium without growth regulators for 25 d in light. In control conditions (in absence of auxin in the first medium), these shoots did not root. Putrescine (PUT), spermidine (SPD), cyclohexylamine (CHA), and aminoguanidine (AG) enhanced rooting when applied during the first d of culture in the absence of IBA; on the contrary, α-difluoromethylornithine (DFMO) added to the first medium with IBA inhibited rooting. The endogenous levels of indole 3-acetic acid (IAA) and indole 3-acetylaspartic acid (IAAsp) increased up to a maximum concentration at days 2 and 3, respectively, in initial rooting conditions. PUT, when added with IBA, did not affect the typical IAA and IAAsp increase; when applied alone, it provoked an increase of their levels. Similar results were recorded with CHA. SPD, AG, and DFMO did not induce an increase of IAA and IAAsp in nonrooting conditions. The levels of endogenous PUT increased to a maximum at day 2 in rooting conditions; it was slightly affected by exogenous PUT and CHA application but reduced by SPD, AG, and DFMO. In rooting conditions, if the first medium was supplemented with SPD or AG, a small increase in peroxidase activity was observed, similar to that obtained with PUT treatment. The present work indicates an involvement of polyamines in the control of rooting and an interaction with auxins during the physiological phase of rooting. The consequence of this relationship was a different rooting expression, according especially to the content of these regulators in the culture medium.     

Polyamines and ethylene in relation to adventitious root formation in Prunus avium shoot cultures

An attempt was made to identify some of the hormonal factors that control adventitious root formation in our Prunus avium micropropagation system in order to improve rooting in difficult-to-root genotypes. Changes in endogenous contents of free polyamines were determined at intervals during auxin-induced rooting of shoot cultures. Accumulation of putrescine and spermidine peaked between days 9 and 11. Spermine was only present in traces, Exogenously supplied putrescine or spermine (50-500 μM), in the presence of optimal or suboptimal levels of indolebutyric acid (IBA), had no effect on rooting percentage or root density, except for spermine at 500 μM. At this external concentration spermine caused a substantial accumulation in both free spermine and putrescine. The use of several inhibitors of polyamine biosynthesis, namely α-difluoromethylornithine (DFMO), α-difluoromethylarginine (DFMA), dicyclohexylammonium sulphate (DCHA) and methylglyoxal-bis-guanyl-hydrazone (MGBG) alone or in combination in the 0.1 to 5 μM range, resulted in an inhibition of rooting that was partially reversed by the addition of the corresponding polyamine. Cellular polyamine levels were significantly reduced by DFMO and DFMA but not by DCHA and MGBG, Labeled putrescine incorporation into spermidine increased somewhat in the presence of the ethylene synthesis inhibitor aminoethoxyvinylglycine (AVG). A system based on [3,4-¹⁴C]methionine incorporation was used to measure ethylene synthesis by the in vitro cultured shoots. Label incorporation was drastically reduced by 10 μM AVG and increased 3.5-fold in the presence of 50 μM IBA with respect to controls (no IBA). Labeled methionine incorporation into spermidine increased to some extent when ethylene synthesis was inhibited by AVG. Adding the ethylene precursor 1-aminocyclopropane-l-carboxylic acid (ACC) to the rooting medium significantly inhibited rooting percentage; AVG caused the formation of a greater number of roots per shoot but delayed their growth. Supplying the shoots with both compounds resulted in an intermediate rooting response, in which both rooting percentage and root density were affected. These results indicate that polyamines may play a significant role at least in some stages of root formation. The polyamine and ethylene biosynthetic pathways seem to be competitive but under our conditions, the enhancement of one pathway when the other was inhibited, was not dramatic. Although IBA promoted ethylene synthesis, AVG, which drastically reduced it, also promoted root formation. Thus, the auxin effect on root induction cannot be directly related to its ability to enhance ethylene synthesis.     

Putrescine and polyamine inhibitors in culture medium alter in vitro rooting response of <Emphasis Type="Italic">Decalepis hamiltonii</Emphasis> Wight &amp; Arn.

The influence of polyamine putrescine (PUT), and polyamine inhibitors were tested for in vitro rooting response from micro shoots that initially established on Murashige and Skoog (MS) medium comprising 2.7 µM α-Naphthaleneacetic acid (NAA) and 8.9 µM 6-Benzylaminopurine (BA) by using nodal explants of Decalepis hamiltonii. Incorporation of putrescine alone in rooting medium devoid of auxins supported the best response for in vitro rooting qualitatively and quantitatively. Incorporation of putrescine at 50 µM able to induce 8.62?±?1.93 roots with a maximum root length of 9.10?±?1.65 cm wherein, the root fresh weight was also found to be high compared to all other treatments (5.248?±?1.71 g). Addition of putrescine inhibitor cyclohexylamine (CHA) in medium curtailed rooting response from microshoots. Among the three polyamine inhibitors, CHA in presence of 9.8 µM Indole-3-butyric acid (IBA) outperformed α-DL-difluromethylarginine (DFMA) and α-DL-difluoromethylornithine (DFMO) combination with 9.8?µM IBA. The least response for root number (1.55?±?0.72), root length (1.96?±?0.45 cm), and root weight (1.94?±?0.35 g) was found for IBA?+?PUT?+?DFMA and the best response was noted for IBA?+?PUT?+?CHA (2.6?±?1.1, 2.92?±?0.73 cm, 3.03?±?0.75 g) respectively. Endogenous content of putrescine, spermidine and spermine supported the rooting response from in vitro shoots. These results have clearly demonstrated that putrescine plays a crucial role in rooting of D. hamiltonii. Plantlets were transferred to micro-pots for a short acclimatization stage in greenhouse where they survived at 90?%. This highly reproducible procedure can be adopted for large scale swallow root propagation. Overall, supplementing putrescine in the rooting medium enhances the quantity and quality of roots in D. hamiltonii, thus confirming its role.     

Polyamines and Adventitious Root Formation in the Juvenile and Mature Phase of English Ivy

The involvement of polyamines during adventitious root formationwas evaluated using a de-bladed petiole rooting assay for theeasy-to-root juvenile and difficult-to-root mature phase ofEnglish ivy (Hedera helix L.). Auxin (NAA 0.1 mM) stimulatedroot formation in juvenile phase cuttings, but failed to promoterooting in the mature phase. The addition of putrescine, spermineor spennidine (1.0 mM) with or without NAA (0.1 mM) did notaffect the rooting response in either the juvenile or maturephase cuttings. There was a significant increase in endogenouslevels of putrescine and spermidine in NAA-treated cuttings,but the only significant difference between the root formingjuvenile and the non-root forming mature phase cuttings wasan increase in putrescine levels. In NAA-treated juvenile cuttings,the polyamine biosynthesis inhibitor DFMA (1.0 mM) promotedroot formation from 9.2 to 14.5 roots per cutting, while DFMO(1.0 mM) reduced root formation from 9.1 to 1.4 roots per cutting.The promotion of rooting by DFMA was completely reversed byputrescine (1.0 mM), but putrescine, spermine or spermidine(1.0 mM) could not reverse the inhibitory effect of DFMO. NeitherDFMA nor DFMO promoted root formation in mature phase cuttings.DFMA was also added to NAA-treated juvenile petioles at variousstages during the root formation process. DFMA promoted rootingwhen applied during the early stages of root induction (0–3d), but became inhibitory to root formation when applied duringthe organization (6–9 d) or root elongation stages (9–12d). Key words: Hedera helix, organogenesis, root initiation, polyamines, DFMA, DFMO     

Polyamines and related enzymes in rice seeds differing in germination potential

In ungerminated rice seeds, (Japonica rice variety, CV Tapei 309), the content of free amines (putrescine, spermidine, spermine, tyramine) was higher in seed lots having a low germination frequency compared to those with high germination potential. Conversely, amine conjugates (di-feruloylputrescine, di-feruloylspermidine, diferuloyldiaminopropane and feruloyltyramine) decreased with loss of viability. Thus, these compounds appeared to constitute biochemical markers of seed viability. In seeds with high germination potential, conjugates decreased drastically during germination, with an early and rapid increase in free amines (putrescine, spermidine, tyramine). Arginine decarboxylase (ADC) activity was highest during the germination of high germination potential seeds, its activity gradually declining with loss of viability and being closely correlated with agmatine content. The polyamine biosynthetic inhibitors (-DL-difluoromethylarginine, DFMA, a specific and irreversible inhibitor of ADC; -DL-difluoromethylornithine, DFMO, a specific irreversible inhibitor of ornithine decarboxylase (ODC); cyclohexylammonium sulfate, CHA, inhibitor of spermidine synthase) neither depleted putrescine and spermidine levels nor inhibited germination in high germination potential seeds. In low germination potential seeds, the germination process was inhibited by DFMA or CHA. Application of agmatine resulted in a reversal of inhibition. DFMA inhibited ADC activity in both categories of seeds. In low germination potential seeds treated with CHA no ADC activity was found. These results suggest that amines are involved in the germination process of rice seeds. It appears that amine conjugates may serve as a storage form of amines which, upon enzymatic hydrolysis, could supply the cell with an additional amine reserve and influence cell division and/or cell elongation.Abbreviations ADC arginine decarboxylase - ODC ornithine decarboxylase - DFMA -DL-difluoromethylarginine - DFMO -DL-difluoromethylornithine - CHA cyclohexylammonium sulfate     

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-inducedsenescence of detached rice leaves was investigated by quantitatinglevels of various polyamines by HPLC. Putrescine, spermidineand spermine were all present throughout senescence. Neithercadaverine nor 1,3-diaminopropane was detected. During dark-inducedsenescence, there was a marked decrease in levels of putrescineand an increase in those of spermidine and spermine. The rateof production of ethylene increased markedly upon excision ofleaves. -Difluoromethylarginine (DFMA) and -difluoromethylornithine(DFMO) caused a reduction in levels of putrescine, yet had noeffect on levels of spermidine and spermine. Neither DFMA norDFMO had any effect on senescence or on the production of ethylene.Treatment with dicyclohexylamine (DCH) and methylglyoxal bis-(guanylhydrazone)(MGBG) reduced levels of spermine and increased those of putrescinein detached leaves. After treatment with DCH or MGBG, both senescenceand the production of ethylene were significantly promoted.The current results suggest that endogenous polyamines may notplay a significant role in the control of dark-induced senescenceof rice leaves. This conclusion is supported by the furtherobservations that (a) benzyladenine, which is known to retardsenescence, decreased levels of putrescine but had no effecton those of spermidine and spermine; and (b) ABA, which promotedsenescence, increased levels of putrescine and had no effecton those of spermidine and spermine. (Received March 30, 1991; Accepted June 27, 1991)     

Polyamine metabolism during seedling development in rice

The main free amines identified during growth and development of rice seedlings were agmatine, putrescine, spermidine, diaminopropane and tyramine. Amine composition differed according to tissue and stages of development. Conjugated amines were only found in roots. We present evidence that arginine decarboxylase (ADC) regulates putrescine during the development of rice seedlings. When ADC action was blocked by DFMA (-DL-difluoromethylarginine, a specific irreversible inhibitor of ADC), polyamine titers and seedling development were diminished; when agmatine or putrescine was added, normal polyamine titers and growth were restored. The effects of DFMA were concentration dependent. DFMO (-DL-difluoromethylornithine, a specific irreversible inhibitor of ornithine decarboxylase or ODC) promoted growth and development at concentrations below 2 mM. This effect was probably related to its unexplained, but consistently observed slight enhancement of rice ADC. When the increase in the concentration of spermidine was prevented by CHA (cyclohexylammonium sulfate), the number of roots increased and the increase in length of leaves and roots was strongly inhibited. The addition of exogenous spermidine at the time of treatment with CHA reversed the inhibition by CHA.Abbreviations ADC arginine decarboxylase - ODC ornithine decarboxylase - DFMA -DL-difluoromethylarginine - DFMO -DL-difluoromethylornithine - CHA cyclohexylammonium sulfate     

Effects of putrescine and inhibitors of putrescine biosynthesis on organogenesis inEuphorbia esula L.

Summary Exogenous putrescine (&#x2264;5 mM) had little effect on root or shoot formation in aseptically isolated hypocotyl segments of leafy spurge (Euphorbia esula L.) grown on full-strength B5 medium. Unexpectedly, putrescine inhibited root and shoot formation in hypocotyl segments grown on B5 medium diluted 10-fold. In the full-strength medium, root and shoot formation were inhibited by 0.5 mM concentrations ofdl-&#x03B1;-difluoromethylornithine (DFMO) anddl-&#x03B1;-difluoromethylarginine (DFMA). DFMO and DFMA are inhibitors of the ornithine decarboxylase and arginine decarboxylase pathways, respectively, of putrescine biosynthesis in plants. Exogenous putrescine (0.5 to 5 mM) did not reverse either the DFMO-or DFMA-induced inhibition of shoot formation. However, the DFMA-induced inhibition of root formation was partially reversed by exogenous putrescine. The auxin, indole-3-acetic acid (IAA), reduced the inhibitory effects of DFMO+DFMA (applied together) on both roots and shoots. In the first few days of culture, the endogenous levels of putrescine and spermidine, but not of spermine, increased in the presence of IAA. The levels of putrescine and spermidine in the tissues did not correlate well with either root or shoot production in the later stages of organ formation; especially in tissues treated with IAA. These results show that there were no obvious correlations between polyamine levels and organogenesis in leafy spurge hypocotyl segments, although residual putrescine or spermidine or both in the tissues at the time of excision may be indirectly involved in the early stages of root formation.     

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     

Physiological and biochemical changes related to methyl jasmonate-induced chilling tolerance of rice (Oryza sativa L.) seedlings

Physiological and biochemical changes related to methyl jasmonate (MeJA)-induced chilling tolerance of rice (Oryza sativa L. cv. Taichung Native 1) seedlings were investigated. Treatment of whole plants with 10 mmol m^?3 MeJA for 48 h before chilling (5 °C) was optimal for the induction of chilling tolerance. MeJA greatly improved the survival ratio of chilled seedlings and ameliorated chilling injury such as demolition of membrane structure (estimated by electrolyte leakage). MeJA also prevented water loss in chilled seedlings by reducing the opening of stomata and decreasing the root bleeding rate. Putrescine and spermine levels in shoots increased but spermidine levels decreased on exposure to MeJA. In roots, putrescine levels also increased and spermidine levels increased transiently on exposure to MeJA. Activities of arginine decarboxylase (ADC; EC 4.1.1.19) and S-adenosylmethionine decarboxylase (SAMDC; EC 4.1.1.50) in both shoots and roots increased on exposure to MeJA, while the activity of ornithine decarboxylase (ODC; EC 4.1.1.17) remained unchanged. The MeJA-induced putrescine increase was inhibited by 50 mmol m^?3α-difluoromethylarginine (DFMA), an irreversible inhibitor of ADC, but not by 50 mmol m^?3α-difluoromethylornithine (DFMO), an irreversible inhibitor of ODC. The effect of MeJA on the induction of chilling tolerance was also reduced by 50 mmol m^?3 DFMA. The effects of DFMA were partly prevented by 1 mol m^?3 putrescine. This indicates that putrescine accumulation is required for the induction of chilling tolerance of rice seedlings by MeJA.     

Changes in peroxidase activity,auxin level and ethylene production during root formation by poplar shoots raised in vitro

Shoots of poplar (Populus tremula × P. tremuloïdes) were multiplied in vitro and rooted on a rooting medium in the presence of NAA. No rooting occurred in the absence of exogenous auxin. A peak of soluble peroxidase activity, which corresponded to a decrease in the free IAA level in the shoots, preceded rooting These events were considered as corresponding to the initiative phase of rooting. They are preceded by a peak in free IAA activity which might initiate the inductive phase of the rooting process. A burst of ethylene production was measured in both rooting and non-rooting shoots, but the ethylene peak from rooting shoots appeared earlier and was higher. The use of ACC indicated that the exogenous auxin might have enhanced ACC-synthetase activity.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - NAA naphthaleneacetic acid - IAA indole-3-acetic acid - 2-iP 2-isopentenyladenine - IAAsp indole-3-acetylaspartic acid - IBA indole-3-butyric acid - GC gas-chromatography     

Levels of endogenous polyamines and NaCl-inhibited growth of rice seedlings

The role of endogenous polyamines in the control of NaCl-inhibited growth of rice seedlings was investigated. Putrescine, spermidine and spermine were all present in shoots and roots of rice seedlings. NaCl treatment did not affect spermine levels in shoots and roots. Spermidine levels in shoots and roots were increased with increasing concentrations of applied NaCl. NaCl at a concentration of 50 mM, which caused only slight growth inhibition, drastically lowered the level of putrescine in shoots and roots. Addition of precursors of putrescine biosynthesis (L-arginine and L-ornithine) resulted in an increase in putrescine levels in NaCl-treated shoots and roots, but did not allow recovery of the growth inhibition of rice seedlings induced by NaCl. Pretreatment of rice seeds with putrescine caused an increase in putrescine level in shoots, but could not alleviate the inhibition effect of NaCl on seedling growth. The current results suggest that endogenous polyamines may not play a significant role in the control of NaCl-inhibited growth of rice seedlings.Abbreviations PUT putrescine - SPD spermidine - SPM spermine     

Plasticity of polyamine metabolism associated with high osmotic stress in rape leaf discs and with ethylene treatment

In rape leaf discs the response to osmotic stress has been found to be associated with increases in putrescine and 1,3-diaminopropane (an oxidation product of spermidine and/or spermine) and decreases in spermidine titers. In contrast, agmatine and spermine titers showed small changes while cadaverine accumulated massively. Similar results were observed in whole rape seedlings subjected to drought conditions. -DL-difluoromethylarginine (DFMA), a specific irreversible inhibitor of arginine decarboxylase, strongly inhibited polyamine accumulation in unstressed rape leaf discs, which suggested that the arginine decarboxylase pathway is constitutively involved in putrescine biosynthesis. In leaf discs treated under high osmotic stress conditions, both DFMA and DFMO (-DL-difluoromethylornithine, a specific and irreversible inhibitor of ornithine decarboxylase) inhibited the accumulation of polyamines. Although the stressed discs treated with DFMA had a lower concentration of putrescine than those treated with DFMO, we propose that under osmotic stress the synthesis of putrescine might involve both enzymes. DFMA, but not DFMO, was also found to inhibit cadaverine formation strongly in stressed explants. The effects on polyamine biosynthesis and catabolism of cyclohexylamine, the spermidine synthase inhibitor, aminoguanidine, the diamine-oxidase inhibitor and -aminobutyric acid, a product of putrescine oxidation via diamine oxidase or spermidine oxidation via polyamine oxidase were found to depend on environmental osmotic challenges. Thus, it appears that high osmotic stress did not block spermidine biosynthesis, but induced a stimulation of spermidine oxidation. We have also demonstrated that in stressed leaf discs, exogenous ethylene, applied in the form of (2-chloroethyl) phosphonic acid or ethephon, behaves as an inhibitor of polyamine synthesis with the exception of agmatine and diaminopropane. In addition, in stressed tissues, when ethylene synthesis was inhibited by aminooxyacetic acid or aminoethoxyvinylglycine, S-adenosylmethionine utilization in polyamine synthesis was not promoted. The relationships between polyamine and ethylene biosynthesis in unstressed and stressed tissues are discussed.     

Polyamines in grapevine microcuttings cultivated in vitro. Effects of amines and inhibitors of polyamine biosynthesis on polyamine levels and microcutting growth and development

The main free amines identified during growth and development of grapevine microcuttings of rootstock 41 B, (Vitis vinifera cv. Chasselas × Vitis berlandieri) cultivated in vitro were agmatine, putrescine, spermidine, spermine, diaminopropane and tyramine (an aromatic amine). Amine composition differed according to tissue, with diaminopropane the major polyamine in the apical parts, internodes and leaves. Putrescine predominated in the roots. There was also a decreasing general polyamine and specific tyramine gradient along the stem from the top to the bottom. Conjugated amines were only found in roots. The application of exogenous amines (agmatine, putrescine, spermidine, tyramine) stimulated development and growth of microcuttings, suggesting that the endogenous concentrations of these amines can be growth limiting. Diaminopropane (the product of oxidation of spermidine or spermine by polyamine oxydases) strongly inhibited microcutting growth and development. -DL-difluoromethylarginine (DFMA), a specific and irreversible inhibitor of the putrescine-synthesizing enzyme, arginine decarboxylase (ADC), led to inhibition of microcutting development. Application of agmatine or putrescine to the inhibited system resulted in a reversal of inhibition indicating that polyamines are involved in regulating the growth and development of grapevine microcuttings. -DL-difluoromethylornithine (DFMO), a specific and irreversible inhibitor of putrescine biosynthesis from ornithine decarboxylase (ODC), had no effect on microcutting development and growth. We propose that ADC regulates putrescine biosynthesis during microcutting development.     

Effects of inhibitors of polyamine biosynthesis and of polyamines on strawberry microcutting growth and development

The primary free polyamines identified during growth and development of strawberry (Fragaria × ananassa Duch.) microcuttings cultivated in vitro were putrescine, spermidine and spermine. Polyamine composition differed according to tissue and stages of development; putrescine was predominant in aerial green tissues and roots. -DL-difluoromethylarginine (DFMA), a specific and irreversible inhibitor of the putrescine-synthesizing enzyme, arginine decarboxylase (ADC), strongly inhibited growth and development. Application of agmatine or putrescine to the inhibited system resulted in a reversal of inhibition, indicating that polyamines are involved in regulating the growth and development of strawberry microcuttings. -DL-difluoromethylornithine (DFMO), a specific and irreversible inhibitor of putrescine biosynthesis by ornithine decarboxylase, promoted growth and development. We propose that ADC regulates putrescine biosynthesis during microcutting development. The application of exogenous polyamines (agmatine, putrescine, spermidine) stimulated development and growth of microcuttings, suggesting that the endogenous concentrations of these polyamines can be growth limiting.Abbreviations ADC arginine decarboxylase - ODC ornithine decarboxylase - DFMA -difluoromethylarginine - DFMO -difluoromethylornithine - Put putrescine - Spd spermidine - Sp spermine - DW dry weight - PA polyamine - PPF photosynthetic photon flux     

Lignosulfonates: Novel promoting additives for plant tissue cultures

Summary Lignosulfonates (LIGNs) are low-cost by-products from the paper industry and are already commercialized as fertilizers. Because earlier laboratory and glasshouse assays had shown a beneficial effect of LIGNs on rooting and general plant vigor, their incorporation in several plant tissue culture types was examined here. The present assays indicated that well-chosen concentrations of LIGNs, whether they were chelated with Ca or Fe, stimulated growth of a normal and an habituated sugarbeet callus, improved multiplication rate and vigor of a shoot-proliferating poplar cluster, and increased the rooting percentage of holly, ginseng, and poplar shoots. Complementing the exogenous rooting auxin with LIGNs enhanced the increases of endogenous levels of indoleacetic acid and its aspartate conjugate in the basal parts of poplar shoots at the rooting inductive phase. Although LIGNs exerted some effects in the absence of the growth regulators, they could not replace them. Their possible mode of action is discussed.     

Effects of exogenous polyamines and difluoromethylornithine on seed germination and root growth of Arabidopsis thaliana

Effects of exogenous polyamines and difluoromethylornithine (DFMO) on seed germination and seedling root growth of Arabidopsis thaliana were investigated. Root growth was stimulated by low concentrations of putrescine but was increasingly inhibited by high concentrations of putrscine. DFMO inhibited root growth and this inhibition was reversed by applying putrescine. In contrast, both spermidine and spermine had no effect on root growth but inhibited seed germination. The results suggest a possible requirement of endogeneous putrescine for normal root growth of Arabidopsis seedlings.Abbreviations DFMO difluoromethylornithine - DFMA difluoromethylarginine - ODC ornithine decarboxylase - Put Putrescine - Spd Spermidine - Spm Spermine     

Changes in Polyamine Contents Development of the Frog, Microhyla ornata

Putrescine, spermidine and spermine levels were measured during development, metamorphosis and adult life of the frog, Microhyla ornata . Development of Microhyla was accompanied by high fluctuating levels of putrescine and spermidine with low and steady levels of spermine. Putrescine was the major polyamine during development from egg to mature tadpole. During metamorphosis both putrescine and spermidine decreased significantly; but the decrease in putrescine content was more rapid than that of spermidine. Thus, in the freshly metamorphosed frog, the concentration of spermidine exceeded that of putrescine. In most of the adult tissues also spermidine concentration was higher than putrescine and spermine. While the free form of putrescine and spermidine increased during early development of the fertilized egg to tadpole, the levels of protein conjugated polyamines decreased. In the free form, putrescine was the major polyamine while in the protein conjugated form spermidine concentration was higher than putrescine and spermine. Thus polyamine pattern is different in early development, during metamorphosis and in differentiated adult tissues of this frog. ∞-Difluoromethylornithine treatment at early blastula stage did not interfere with the normal development of Microhyla embryos.     

Anatomical and Biochemical Events duringin vitroRooting of Microcuttings from Juvenile and Mature Phases of Chestnut

A comparative study of thein vitrorooting process of chestnut(Castanea sativa)shoots of the same genotype exhibiting juvenile(easy-to-root) and mature (difficult-to-root) characteristicsis described. The two culture lines originated from shoots collectedfrom the base (juvenile) and crown (mature) of an 80-year-oldtree. Anatomically, juvenile and mature shoots had a similarstem structure at the time of excision, the main differencebeing that secondary phloem and xylem were more developed inmature than in juvenile shoots. A substantial reactivation ofcell division was observed in both shoot lines 48 h after theroot inductive treatment with indole-3-butyric acid. Meristemoidsand root primordia developed only in juvenile shoots, beginning3 d after the inductive treatment, and the first adventitiousroots emerged 10 d after treatment. However, in mature shootspericlinal divisions of cambial cells occurred, especially onthe phloem side, maintaining the normal orientation of the cambialderivatives. No meristemoids formed in this proliferating tissue.During the time course of the rooting process, more endogenousindole-3-acetic acid (IAA) was detected in mature than in juvenileshoots, indicating that the level of IAA is not the limitingfactor accounting for the lack of rooting capacity in matureshoots. The levels of polyamines (putrescine, spermine and spermidine)were also higher in mature than in juvenile shoots.Copyright1999 Annals of Botany Company Adventitious rooting, anatomy, auxins,Castanea sativaMill., chestnut, juvenile phase, mature phase, polyamines, tissue culture.