Exogenous Application Of Polyamines Research Articles

Endogenous and exogenous polyamines in the organogenesis in Curcuma longa L.

The present work evaluated the development of different Curcuma longa L. explants (leaves basis, root tips and ancillary buds from rhizome) stimulated by exogenous polyamines, combined with naphtalen-acetic acid (NAA) or with 6-benzyl-aminopurine (BAP), to produce callus and its subsequent differentiation. The explants, isolated from field plants, were previously subjected to a basic cleaning method and were inoculated onto Murashige and Skoog culture medium (MS) [Murashige, T.S., Skoog, F., 1962. A revised medium for rapid growth and bioassays with tobacco tissue culture. Physiologia Plantarum 15, 473–497] supplemented with NAA (2.0 mg L −1). Buds were subjected to different treatments, with or without 5.0 and 10.0 mmol L −1 exogenous polyamines (mixture of putrescine:spermine:spermidine, 1:1:1) combined with NAA. The calluses obtained were transferred into the same medium, supplemented with the mixture of polyamines combined with BAP, in order to induce plant differentiation. For C. longa, buds were the most efficient explants for callus induction ( p < 0.05). The application of exogenous polyamines (5.0 and 10.0 mmol L −1) produced the most developed callus, with numerous roots. The medium supplemented with 10 mmol L −1 polyamine mixture, combined with BAP, induced good regeneration, producing vigorous plants and excellent shoot formation.Polyamines addition promoted the formation of callus, roots and leaves, representing an important factor in the determination of indirect organogenesis in C. longa L., and putrescine content may be considered a valuable marker of the differentiation process in this specie, as well as the enzyme peroxidase.

An efficient procedure for embryogenic callus induction and double haploid plant regeneration through anther culture of Thai aromatic rice (Oryza sativa L. subsp. indica)

Anther culture is a biotechnology technique that can be used for the production of pure lines. The aims of this investigation were to induce embryogenic callus from major and minor culms of Thai aromatic rice cultivars and to subsequently regenerate double-haploid green plantlets by the application of exogenous polyamines. Embryogenic callus derived from anther culture was successfully induced in varieties KDML105, Homjan (HJ), and Pathumthani 1 (PT1). Production of embryogenic callus from anthers collected from the major culms was greater than those collected from the minor culms, especially in cultivar HJ. Plantlet regeneration in the three rice cultivars was observed from embryogenic callus and was highest, at 12.1%, from variety HJ treated with 0.5 mM spermidine. Plantlet regeneration from anther-derived embryogenic callus was dependent on the plant genotype, the types of exogenous polyamines, and the interactions of these factors. The percentage of haploid plantlets regenerated in PT1, KDML105, and HJ were 68.1%, 70.7%, and 78.5%, respectively. Only haploid plantlets were treated with colchicine for double-haploid production. This investigation has increased the knowledge of both embryogenic callus induction and plantlet regeneration in aromatic rice and has lead to the development of a pure, double-haploid line for the use in rice breeding programs in Thailand.

Evidence of Symbiosis Between the Soil Yeast Cryptococcus laurentii and a Sclerophyllous Medicinal Shrub, Agathosma betulina (Berg.) Pillans

The interaction between a common soil yeast, Cryptococcus laurentii, and a slow-growing medicinal plant adapted to low-nutrient soils, Agathosma betulina (Berg.) Pillans, was studied. C. laurentii CAB 578 was isolated from the rhizosphere of wild A. betulina, and liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis revealed that the yeast was capable of producing polyamines, such as cadaverine and spermine, while growing in vitro in a chemically defined medium. Since the exogenous application of polyamines are known to impact on root growth, these findings supported the results obtained when axenic cultures of A. betulina seedlings were inoculated with C. laurentii CAB 578 and cultivated for 5 months under glasshouse conditions. The presence of the yeast increased root growth by 51%. Using soil dilution plates, it was demonstrated that yeast numbers were greater in the vicinity of the roots than in the bulk soil. In addition, fluoromicroscopy, in combination with the fluorescent probes Fungolight and Calcofluor white, revealed the presence of metabolic active yeast colonies on the rhizoplane 5 months after initiation of the experimentation. The study provided evidence for a symbiosis between C. laurentii and A. betulina.

INFLUENCE OF NITROGEN NUTRITION OF GRAPEVINES ON THEIR POLYAMINE METABOLISM IN FLOWERS AND BERRIES

Polyamines (PAs) seem to play an overwhelming role in plant growth and developmental processes. They are found to be essential for cell viability, cell division, prolongation of cell division, and cell elongation and modification (Evans and Malmberg, 1989; Heimer et al. 1979; Mader and Hanke 1997 and Berta et al. 1997). Correlations were found between increase of PA-levels with cell division and a drop in PAs during reduction of metabolic activity (Evans and Malmberg, 1989). Berlin and Forche (1981) reported that low doses of a-DL-difluoromethyl¬ornithine (DFMO) inhibited cell division in tobacco cell cultures, but not their enlargement. Bondi et al. (2000) have reported that the treatment of root cultures of Hyocyamus nutieus with jasmonates increased the putrescine level and also moderately the tropane alkaloid levels. A hypothesis exists that PA’s and ethylene production may regulate each others synthesis, either directly or by metabolic competetion for S-adenosylmethionine (SAM). PA’s inhibit ethylene formation in several plant tissues, i.e. apple fruits, bean and tobacco leaf explants (Apelbaum et al. 1984) Exogenous feeding of putrescine (Put) resulted in reduced ethylene production (Bais et al. 2000a). There exists also some information that PAs are involved in the fertilization process of different plants and their fruit set. Broquedis et al. (1996) could demonstrate that the exogenous application of PAs increased the percentage of fertilization in grape flowers. In the present study complete vine plants (Vitis vinifera L. cv. Riesling) were analysed in their different organs during growing season to achieve an insight in the dynamics of free PAs in that species. The time course of changes in the concentrations of PAs will probably give a better understanding of the flowering and fruit set process in grapevines. The observations were made in a N-fertilizer trial in order to see the additional interactions between nitrogen nutritional status, PAs and fruiting.

New perspective on the mechanism of alleviating salt stress by spermidine in barley seedlings

Salt stress is considered to be a major limiting factor for plant growth and crop productivity. Salt injuries in plants are mostly due to excess Na+ entry. A possible survival strategy of plants under saline environments is the effective compartmentation of excess Na+ by sequestering Na+ in roots and inhibiting transport of Na+ from roots to shoots. Our previous study showed that exogenous application of polyamines (PAs) could attenuate salt injuries in barley plants. In order to further understand such protective roles of PAs against salt stress, the effects of spermidine (Spd) on sodium and potassium distribution in barley (Hordeum vulgare L.) seedlings under saline conditions were investigated. The results showed that exogenous application of Spd induced reductions in Na+ levels in roots and shoots with comparison of NaCl-treated plants, while no significant changes in K+ levels were observed. Correspondingly, the plants treated with Spd exogenously maintained high values of [K+]/[Na+] as compared with salt-stressed plants. Moreover, it was shown by X-ray microanalysis that K+ and Na+ accumulated mainly in the exodermal intercellular space and cortical cells of roots under salinity stress, and low accumulation was observed in endodermal cells and stelar parenchyma, indicating Casparian bands possibly act as ion transport barriers. Most importantly, Spd treatment further strengthened this barrier effects, leading to inhibition of Na+ transport into shoots. These results suggest that, by reinforcing barrier effects of Casparian bands, exogenous Spd inhibits Na+ transport from roots to shoots under conditions of high salinity which are beneficial for attenuating salt injuries in barley seedlings.

Improved fruit retention, yield and fruit quality in mango with exogenous application of polyamines

Aqueous solutions (0, 0.01, 0.1, 1 mM) of PAs (putrescine, spermine, spermidine) containing a surfactant ‘Tween 20’ were sprayed onto panicles of mango (Mangifera indica L. cv. Kensington Pride) at final fruit set (FFS) stage (when all flowers abscised but remain attached to the panicle) during 1999–2001 to investigate their effects on fruit retention, yield, size, and fruit quality. The optimum time of PA application for improving final fruit retention and fruit yield was determined by spraying different concentrations (0, 0.01, 0.1, 1 mM) of spermine (SPM) containing a surfactant ‘Tween 20’ at four phenological stages including flower bud differentiation (FBD), 5–8 cm long grown panicles (GP), full bloom (FB) and at initial fruit set (IFS) stage (when 2/3rd of the flowers were abscised but attached to the panicle) during 2000. Exogenous application of PAs at FFS stage did not significantly increase fruit retention. However, compared to control (0.79 and 2.3% fruit retention), PAs treatments resulted in comparatively higher mean fruit retention (1.53 and 2.92%) during 1999–2000 and 2000–2001, respectively. Among three PAs tested, SPM was more effective in increasing mean final fruit retention. Fruit size was not significantly affected by any PA treatment. Among the four application times, SPM (0.01 mM) spray at FB stage resulted in significantly (P � 0.05) greater fruit retention (4.99%) compared with control (2.1%). However, fruit yield was comparatively higher with SPM (0.01 mM) application at IFS stage or 5–8 cm GP stage compared to the control. Overall FB application was found as the optimum time of application. Application of PAs at FFS stage retarded fruit skin colour development compared to the control. Sugars and total soluble solids (TSS) were generally reduced in PA-treated fruit. Fruit acidity was increased (16.7%) with SPM, whereas it was 11% with PUT treatment as compared to the control. Total carotenoids in pulp were generally improved (49%) with PA treatments, compared to the control. Ascorbic acid concentrations were significantly reduced with spermidine (SPD) (24%) and PUT (20%) treatments, whereas higher concentrations of SPM (1 mM) tended to increase it (12.7%) compared to the control. In conclusion, application of SPM (0.01 mM) at FB stage resulted in the highest fruit retention, whereas SPM (0.01) spray at GP or IFS stage resulted in higher fruit yield. PUT application at FFS stage significantly improved fruit quality by increasing total carotenoid, while reducing acid content of ripe fruit. # 2006 Elsevier B.V. All rights reserved.

EXOGENOUS APPLICATION OF POLYAMINES IMPROVES SHELF LIFE AND FRUIT QUALITY OF MANGO

This research aimed to investigate the benefit of postharvest application of polyamines {Spermine (SPM), Spermidine (SPD) and Putrescine (PUT)} on the shelf life and fruit quality of mango (Mangifera indica L. cv Kensington Pride). Polyamine application retarded fruit softness, colour development and reduced physiological weight loss during storage without a significant reduction in ethylene production. Lower concentrations of SPM (0.01 mM), and higher concentrations of SPD (0.5 mM) and PUT (1 mM) were more effective in retarding fruit softening. During fruit ripening, SPM (0.01 mM) exhibited the minimum respiration compared with the control fruit. Analysis of ripe fruit, which were stored for 3 or 4 weeks, showed that polyamine application significantly increased fruit firmness, acidity, ascorbic acid, while reducing the TSS/acid ratio and total carotenoid content compared with the control. The exogenous application of polyamines improved shelf life of mango without having deleterious effect on fruit quality. INTRODUCTION Mango is one of the most popular summer fruit in both domestic and international markets owing to its delicious taste and aroma. However, a short shelf life remains one of the major impediments in the market and to increasing international trade, despite several research efforts in the past to extend its storage life. Mango is a climacteric fruit, often harvested at the mature, hard green preclimacteric stage. The ripening process involves numerous rapid biochemical changes and is triggered by ethylene, whether derived from endogenous or exogenous sources (Wills et al., 1989). Polyamines {Spermine (SPM), Spermidine (SPD) and Putrescine (PUT)} and ethylene production are interrelated, since they share a common precursor (SAM) (Kakkar and Rai, 1993). Therefore, there is a possibility that polyamines may regulate the process of fruit ripening and storage. However, such a relationship between polyamines (PAs) and ethylene has yet to be determined in mangoes. Exogenous application of PAs has reduced fruit softening, and delayed senescence in various fruits (Kramer et al., 1991). The application of SPM (0.3, 3 mM) to papaya as a fruit dip treatment for 30 minutes before ripening at room temperature resulted in delayed softening, lower colour score, but did not retard weight loss. SPM (3 mM) extended the shelf life by up to 2.6 days, while SPD and putrescine at the highest concentrations retarded weight loss, but had no other effects (Purwoko et al., 1998). Mango fruit cv 'Arumanis' were pressure infiltrated (0.72 kg/cm for 3 min) with PUT (1, 3, 10 mM), SPM and SPD (0.3, 1, 3 mM) and then ripened at room temperature (28oC). PAs treatments maintained significantly higher fruit firmness than the controls, and SPM and SPD performed better than PUT (Purwoko et al., 1998). Likewise, the beneficial effects of PAs applications have also been reported during storage of different fruits (Valero et al., 1998, 2002). The effects of postharvest application of PAs on mango fruit during storage, and

Protective effect of exogenous polyamines on root tonoplast function against salt stress in barley seedlings

Salinity stress is one of the most serious factors limiting the productivity of agricultural crops. A possible survival strategy of plants under saline conditions is to sequester excess Na+ in the vacuole by vacuolar Na+/H+ antiport using a pH gradient generated by H+-ATPasc (EC 3.6.1.35) and H+-Pyrophosphatase (H+-PPase; EC 3.6.1.1) to maintain a higher K+/Na+ ratio in cytoplasm. The effect of exogenously applied polyamines (PAs) in stabilizing root tonoplast integrity and function against salt stress in the barley (Hordeum vulgare L.) seedlings was investigated. The NaCl-induced reductions in the contents of phospholipids and PAs in tonoplast vesicles isolated from barely seedling roots, as well as the activities of H+-ATPase, H+-PPase and vacuolar Na+/H+ antiport were all partially restored by the application of 0.5 mM putrescine and 0.5 mM spermidine, especially the former. The above results indicated that one of the mechanisms involved in attenuating salt injury in barley seedlings by exogenous PAs application was to maintain tonoplast integrity and function under saline conditions. Moreover, the possible mechanism involved in counteracting detrimental effects of salt on the barley seedlings by the application of exogenous PAs was discussed.

Abscission of mango fruitlets as influenced by biosynthesis of polyamines

SummaryThe role of polyamines in fruitlet abscission of mango (Magnifiera indica L.) was studied by estimating the endogenous polyamines in intact and about-to-abscind fruitlets and their pedicels, and the effect of exogenous applications of polyamines and inhibitors of polyamine biosynthesis. Endogenous free polyamines (putrescine, spermidine and spermine) were estimated in intact and about-to-abscind fruitlets and their pedicels at three developmental stages in ‘Kensington Pride’ and ‘Glen’ mango. Intact fruitlets and their pedicels exhibited 276% and 341% higher total free polyamines than about-to-abscind ones in ‘Kensington Pride’, whilst in ‘Glen’; the increase was 137% and 63%, respectively. Mean spermine concentrations were higher in intact tissues of ‘Kensington Pride’ (fruitlets 220 nmol g–1 FW, pedicels 172 nmol g–1 FW), while spermidine concentrations were greater in ‘Glen’ (fruitlets 244.5 nmol g–1 FW, pedicels 256 nmol g–1 FW). The role of spermine seems to be critical in mango fruitlet abscission as the about-to-abscind fruitlets had very low levels of spermine (10.4% and 19% of intact fruitlets) in ‘Kensington Pride’ and ‘Glen’, respectively. Exogenous applications of polyamines reduced fruitlet abscission during the initial heavy fruitlet abscission period (two weeks after fruit set) and the response was significantly influenced by type, concentration and time of application. Spermidine (0.1 mM) was the most effective of the three polyamines applied at the fruit-set stage, reducing fruitlet abscission by 6.8% compared with the control. Of the four times of application, spermine (0.1 mM) sprayed when the panicle had grown 5–8 cm showed least fruitlets abscission (91.5%) compared with controls (95.5%) after six weeks of fruit set. Higher levels of endogenous polyamines in intact fruitlets and their pedicels, compared with about-to-abscind ones, and the reduction of fruitlet abscission with exogenous application of polyamines, as well as the acceleration with inhibitors of polyamines, demonstrate the key role of polyamines biosynthesis in mango fruitlet abscission.

REGULATION OF FRUIT SET AND RETENTION IN MANGO WITH EXOGENOUS APPLICATION OF POLYAMINES AND THEIR BIOSYNTHESIS INHIBITORS

REGULATION OF FRUIT SET AND RETENTION IN MANGO WITH EXOGENOUS APPLICATION OF POLYAMINES AND THEIR BIOSYNTHESIS INHIBITORS

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. α-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. α-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.

Increased fruit set and retention in mango with exogenous application of polyamines

SummaryAqueous solutions of putrescine, spermine and spermidine of different concentrations (10−3, 10−4, 10−5, 10−6M) were sprayed onto panicles prior to anthesis or at full bloom, to study effects on fruit set and retention of the two self-incompatible cvs Langra and Dusheri, of mango (Mangifera indica L.). Putrescine (10−4M) increased fruit set in ‘Dusheri’ when applied prior to anthesis whereas spermine (10−4M) was most effective in stimulating fruit set in ‘Langra’ when applied at full bloom. The application of polyamines at full bloom resulted in higher fruit retention than when applied prior to anthesis. Spermine was more effective than putrescine or spermine in increasing fruit retention in both cultivars. Spray application of spermine (10−3M) prior to anthesis and putrescine (10−4M) at full bloom were most effective in increasing the final fruit retention in cvs Dusheri and Langra, respectively.

Endogenous polyamine content during in vivo maturation and in vitro culture of maize pollen

Changes in polyamine content during in vivo maturation and in vitro culture of maize (Zea mays L.) pollen were studied. The endogenous content of free, conjugated and bound polyamines was analyzed during 30 days of pollen evolution, in both developmental pathways (microsporogenesis and androgenesis). The induction of androgenesis from cold-pretreated uninucleate pollen results, in most of cases, in a lower total polyamine content than that of the in vivo uninucleate pollen. These differences indicate that polyamine metabolism is altered during the induction of androgenesis, and this could be a consequence of increased polyamine assimilation. In general, pollen stages that involve cell division (tetrades, pre-anthesis pollen and four-day cultured pollen) are characterized by a predominance of free Spd. The increase of Spd and Spm in 15-day cultured pollen, when the first embryoids are formed, outline the possible implication of these polyamines in embryogenetic processes. Furthermore, these findings may contribute to the improvement of maize androgenesis yield, especially in recalcitrant genotypes, by the exogenous application of polyamines or polyamine-inhibitors to the culture medium.