Effet de l'acide gibberellique (GA3) sur la croissance d'Asparagopsis armata (Rhodophycées,Bonnemaisoniales) en culture

Abstract

Effect of gibberellic acid (GA₃) on the growth of Asparagopsis armata in culture.—The gibberellic acid (GA₃) stimulates the growth of the Asparagopsis armata in culture. This effect was observed by adding doses of 6,5X10^?5M or 6,5X10^?7M of this acid in Von Stosch medium.     

Ulteriori ricerche sulla germinazione di Cercis siliquastrum L. Azione dell'acido gibberellico e ruolo dell'endosperma nel fenomeno della dormienza

Abstract

Further research on the germination of Cercis siliquastrum L. Effect of gibberellic acid (GA₃) and role of endosperm in dormancy.—In order to locate the causes of the dormancy in Cercis siliquastrum L., researches have been carried out also on non-scarified seeds without integument, as well as on isolated embryos.

We have noted that gibberellic acid can substitute the cold treatment to interrupt the dormancy and we have also investigated the optimal concentrations.

The results we have obtained do not show the inhibition to be located in the integument and point out a determinant role of the endosperm.

Histological investigations are being carried out to study better the possible occurrence of a mechanical restraint imposed by the albumen on the non-dormant embryo.     

Modification of logarithmic growth rates of tobacco callus tissue by gibberellic Acid

Logarithmic growth rates (either fresh or dry weight basis) of tobacco callus tissues grown on 10⁻⁴ to 10⁻¹ μm cytokinin are increased if gibberellic acid (10⁻³-2 μm) is incorporated into the medium. At higher (1-10 μm) cytokinin concentrations gibberellic acid has little effect on growth rate but extends the duration of logarithmic growth. The gibberellic acid effect is noticeable only after one weight doubling, is dependent on concentration, and occurs when either glucose or sucrose is used as carbon source. The gibberellic acid response includes a decrease in percentage of dry weight relative to control tissues. The maximum dry weight yield, although achieved sooner than controls, does not differ appreciably from yields of tissue not treated with gibberellic acid.     

Effect of silicone oil on gibberellic acid production by Gibberella fujikuroi and Aspergillus niger

The effect of silicone oil on gibberellic acid production was investigated using Gibberella fujikuroi and Aspergillus niger fungi. Silicone oil was used as an oxygen vector in the gibberellic acid production process. When silicone oil was used, the concentration of gibberellic acid increased 4.6 and 6.7 times with respect to the control run having A. niger and G. fujikuroi microorganisms, respectively. The text was submitted by the authors in English.     

Plant growth regulator interactions results enhancement of antioxidant enzymes in Catharanthus roseus

Abstract

The present investigation was carried out with the objectives to understand the effect of paclobutrazol, gibberellic acid and Pseudomonas fluorescens on the enzymatic antioxidants like Ascorbate peroxidase (APX, EC: 1.11.1.11), Superoxide dismutase (SOD, EC: 1.15.1.1), Catalase (CAT, EC: 1.11.1.6), Peroxidase (POX, EC 1.11.1.7) and polyphenol oxidase (PPO, Ec 1.10.3.1) activities of Catharanthus roseus plants under field conditions. 10 mg l^?1 paclobutrazol, 5 µM gibberellic acid and 1 mg P. fluorescens concentrations were used for the treatments, and control plants were irrigated with well water. The treatments were given 38, 53, 68 and 83 days after planting (DAP) by soil drenching. The plants were taken randomly 45, 60, 75 and 90 DAP and separated into root, stem, leaves and flowers and used for estimating the antioxidant enzymes. The results showed that these plant growth regulators have significant effects on antioxidant enzymes of C. roseus.     

Azione Esercitata Da Alcuni Inibitori Respiratori Sull'Inverdimento Di Apici Caulinari Di Piantine Eziolate Di Pisello

Abstract

Action of some respiratory inhibitors on the greening of apices of etiolated pea. — Aim of the research is to study the effect of some of the best kown respiratory inhibitors on the greening of etiolated apices of peas excised from the plant and kept in light in solutions containing saccharose. The inhibitors studied may act on more than one of the reactions leading to the synthesis of the chlorophyll molecule.

The following can be concluded from the present study:

1. A good level of chemical energy seems to be necessary for greening.

2. Terminal iron-oxidases seem to be necessary in this process, while a stimulating effect on greening may be attributed to an inhibition of the terminal copper-oxidases (particularly ascorbic-oxidase); the effect can be explained with the hormonal control of greening by the indoleacetic/ascorbic system.

3. Enzymes of the Krebs cycle regulate both the uptake of the essential metabolites starting from the chlorophyll molecule and the production of chemical energy.

4. Some enzymes of the glycolysis take part in some of the reactions leading to the synthesis of the chlorophyll molecule.     

Effects of gibberellic acid and zeatin on the growth response of cucumber cotyledons

In contrast to cytokinin, gibberellic acid has no effect on the growth of the isolated cucumber cotyledon in darkness. Like cytokinins in light, gibberellic acid causes increases in fresh weight and area of the cotyledon at concentrations from 10^–7 to 10^–3 M. Radiant energies in the blue, red, and far-red regions of the spectrum all induce the growth responses to gibberellic acid. The effect of the far red is greater than that of the red, which is greater than that of the blue. Gibberellic acid is ineffective in the promotion of chlorophyll development, whereas cytokinins are very effective. Although zeatin and gibberellic acid both cause an increase in fresh weight and area of the cotyledons in light, they appear to have entirely separate actions in the growth responses.     

Gibberellic acid-induced prolongation of the dormancy in tubers or rhizomes of several species of East Asian Dioscorea

Effects of the application of gibberellic acid on sprouting of tubers or rhizomes were tested in seven species of the genus Dioscorea that are native to the temperate regions of East Asia. The lowest concentrations for significant inhibition of sprouting in these species varied from 0.1–1 µM Application of gibberellic acid at 100 µM inhibited sprouting for more than 500 days at 20 °C. Some responses to the application of gibberellic acid differed between species and between sections of the genus. In D. japonica, the application of gibberellic acid inhibited sprouting of tubers and bulbils while it promoted seed germination.     

Promoting Effect of Fusicoccin on Seed Germination

The effects of fusicoccin on the germination of dormant, light-requiring or abscisic acid-inhibited seeds has been investigated. (1) Fusicoccin (10^?6M) induces germination in dormant wheat seeds (Triticum durum cv. Cappelli; 1972 crop) and stimulates it in seeds already relieved from dormancy (1971 crop), with an effect similar to that of gibberellic acid. (2) Fusicoccin (1.5 × 10^?6M) is more active than the two phytohormones gibberellic acid and benzyladenine and than white light in stimulating light-requiring lettuce seeds (Lactuca sativa cv. Grand Rapids) to germinate. Germination of radish seeds (Raphanus sativus) is also accelerated by fusicoccin, while benzyladenine and gibberellic acid are less active in this material. (3) Fusicoccin (1.5 × 10^?5M) removes almost completely the inhibitory effect of abscisic acid on germination of radish and lettuce seeds, whereas benzyladenine (10^?4M) and gibberellic acid (3 × 10^?4M) remove the inhibition only partially. The possible relationship between these results and previous information on growth by cell enlargement is discussed in terms of the mechanism of action of fusicoccin as compared with natural hormones.     

Responsivencess of Intact and Scarified Seeds of Barbarea vulgaris to Gibberellic Acid and Changes in Phytochrome

Either red light or millimolar levels of gibberellic acid promoted germination of seeds of yellow rocket (Barbarea vulgaris R. Br.), and their effects were generally additive. Buffering the substrate pH at 3.0, addition of 20 mM nitrate to the substrate, preliminary incubation at 10 or 30°C, and brief scarification of the seeds increased responsiveness of the seeds to gibberellic acid. Scarification increased several thousandfold the sensitivity of the seeds to gibberellic acid. Pretreatment of the seeds in darkness or far-red light did not lower their responsiveness to gibberellic acid. These results suggest that uptake of gibberellic acid is a limiting factor in the stimulation of germination in intact seeds and that there is only a minimal requirement for active phytochrome to express gibberellic acid action.     

Hormonal effects on phyllotaxis ofEuphorbia lathyris L.

Benzyladenine and gibberellic acid sprays (100 mg/l) onEuphorbia lathyris L. plants were absolutely successful (100% of the plants) in inducing a change in its normal decussate phyllotaxis. Benzyladenine produced a change to tetracussate, tricussate and bijugate, and gibberellic acid to spiral phyllotaxis. Benzyladenine and gibberellic acid treatments resulted in a significant increase in apex diameter (72.8% and 19.1% respectively). CCC, Ancymidol, Alar and Glyphosine did not alter decussate phyllotaxis.     

Sulle Cause Determinanti La Formazione Di Tumori in Ibridi Di Nicotiana

Abstract

Cause of tumor formation in NICOTIANA hybrids. Further serological studies. — Additional researches have been carried out about genetical tumors in genus Nicotiana. By means of serological procedure the affinity among pairs of species that give rise to tumorous and non-tumorous hybrids has been tested, considering also their phyletic interrelation. Using ion exchange chromatography a qualitative analysis of the total proteins of tumorous and non-tumorous tissue of hybrids and of normal leaves taken from hybrids and their parental species was carried out. Serological analysis of affinity between the species tested gave following results:

1) higher serological affinity was found between species belonging to the same subgenus than between species belonging to different subgenera.

2) serological affinity between pairs of species giving rise to tumorous hybrids is higher than the affinity observed between other pairs of species that give rise to normal hybrids in spite of the same sistematic position. The same serological responses were obtained studying many species of Nicotiana with the single apparent exception of N. langsdorffii. The results of chromatographical analysis have revealed a high constancy of protein composition of the normal and tumorous tissue of hybrids. This conferms the genetical uniformity of the whole plant.     

Hormonal content and sensitivity of transgenic tobacco and potato plants expressing single rol genes of Agrobacterium rhizogenes T-DNA

The expression of single rol genes of the T_L-DNA of Agrobacterium rhizogenes strain A4 in transgenic tobacco (Nicotiana tabacum L.) and potato (Solanum tuberosum L.) plants alters the internal concentrations of, and the sensitivity to, several plant hormones. The levels of immunoreactive cytokinins, abscisic acid, gibberellins and indole-3-acetic acid were analysed in tissues of the apical shoots, stems, leaves, roots and undifferentiated callus tissue. The addition of the dominant and morphogenetically active rolA, rolB, or rolC genes resulted in alterations in the content of several hormones. rolC overexpression in particular led to an up to fourfold increase in the content of isopentenyladenosine, dihydrozeatin riboside and trans-zeatin riboside-type cytokinins in potato plants. This increase correlated well with different levels of expression of the rolC gene in different transgenic plants. Furthermore it was shown that the dwarfism of P_35s-rolC transgenic tobacco and potato plants is correlated with a 28–60% reduction of gibberellic acid A₁ concentration in apical shoots. Exogenous addition of gibberellic acid completely restored stem elongation in P_35s-_rolC transgenic plants. Apical shoots of dwarf rolA transgenic tobacco plants also contained 22% less gibberellic acid A₁ than control plants, but growth cannot be restored completely by exogenously added gibberellic acid. Similarly, the sensitivity of transgenic tobacco seedlings or callus tissues towards different phytohormone concentrations can be altered by the expression of single rol genes. The overexpression of the rolC gene in seedlings led to an altered response to auxins, cytokinins, abscisic acid, gibberellic acid and the ethylene precursor 1-aminocyclopropane-carboxylic acid. The overexpression of the rolB gene in tobacco calli led to necrosis at lower auxin concentrations than in the wild-type, while other parameters of auxin action, like the induction of cell growth, remained unchanged.     

Effects of plant growth regulators on three wood-rotting polypores

The results of the effects of plant growth regulators, kinetin, gibberellic acid, 3-indoleacetic acid and ethrel (2-chloroethylphosphonic acid) on three wood-rotting polypores,viz. Polyporus palustris, Daedalea flavida andTrarnetes badia, are given. 3-Indoleacetic acid, kinetin and gibberellic acid increased the dry mass and protein, and decreased free amino acids, while ethrel decreased dry mass and protein, and increased free amino acids inP. palustris. All the treatments decreased dry mass and protein, and increased free amino acids inD. flavida. Kinetin decreased dry mass and protein, and increased free amino acids whereas 3-indoleacetic acid, gibberellic acid and ethrel increased dry mass and protein, and decreased free amino acids inT. badia over the control. The effects were most pronounced in the three species upon treatment with 50 μm kinetin, 50 μm gibberellic acid, 50 μm 3-indoleacetic acid and 25 μm ethrel. Among the treatments, the effects of 3-indoleacetic acid were most marked in enhancing growth, measured by dry mass ofT. badia out of the three species studied.     

Sviluppo Vegetativo E Riproduttivo Di Alcune Longidiurne in Rapporto All'Azione Dell'Acido Gibberellico

Summary

Continuing the experiments on the action of Gibberellic acid on growth and development of herbaceous plants, the Authors have examined once more several species which require “long day” for espletion of some phases of their reproductive development.

The principal aim was to bring into evidence whether Gibberellic acid can really substitute for some manifestations of the reproductive development itself, or whether some apparent manifestations of reproductive development provoked by this substance are due primarily to modifications of vegetative processes determinated by it.

The experiments were carried out on Papaver somniferum L., Centaurea calcitrapa L., Oenothera acaulis L., Aethusa Cynapium L. and Myosurus minimus L.

Results obtained on Papaver somniferum demonstrate that Gibberellic acid accelerates the macroscopic flowering manifestations under short day conditions of plants already induced to flowering, substituting in this for the effect of “long day” factor in so far as concerns the lengthening of the floral axis. No experiments which can establish whether Gibberellic acid may have an action on specific processes involved in the transition to the reproductive stage, have so far been conducted on Papaver.

Experiments on Centaurea calcitrapa have revealed that Gibberellic acid, treatment though promoting in plants manteined in short-day conditions a “bolting” effect simulating that obtained usually only at long-day, does not succeed in flowering this is true in our experimental conditions (experiments limit: 10 weeks; (photo-phase at light intensity inferior to 2000 lux). Experiments on Centaurea were also supplemented with histological observation of esperimental material.

In the experiments on Oenothera acaulis, a long-day plant only for the macroscopic development phase of floral apparatus, and indeterminate for the formation of floral primordia, has been noted that Gibb. acid can, in the long run, partly substitute for the long-day effect. However, development of floral structures at shortday, is more easily obtained if the plants are supplied, besides with Gibberellic acid, also with other stimulating and trophic substances. This and others observations may indicate that Gibberellic acid represent only one of the substances involved in the metabolism of plants under long-day conditions.

Aethusa Cynapium has furnished results similar to those obtained with Centaurea, even if within very long experimental limits some apparently indirect action of Gibberellic acid towards flowering may occurs.

Preliminary experimental data on logday Myosurus minimus L. show that Gibberellic acid can substitute sooner or later for longday requirements in flowering. In fact, two months old plants flower when Gibberellic acid is supplied under 9 hr. shortday conditions while the controls in shorday remain vegetative. We must note that Myosurus flowers better when light extension is prevalently constituted by far red radiation the effect of which is apparently substituted more easily by Gibberellic acid even if its action appears less afficient and rapid than that of supplementary illumination.     

Production of essential oils by flowers of Hyacinthus orientalis L. regenerated in vitro

Essential oils were produced by flowers of Hyacinthus orientalis L. that had been regenerated in vitro. The production of these oils was affected by the concentration of gibberellic acid and sucrose in the medium and by temperature. The highest concentration of essential oils was obtained when regenerated flowers were cultured in vitro for 3 weeks at 20 °C on Murashige and Skoog's medium that contained 30 g/l sucrose plus 1 mg/l gibberellic acid, whereas the highest amount of essential oils was obtained after a culture period of 3 weeks at 25 °C. The composition of essential oils from flowers that had been regenerated in vitro was compared with that from flowers grown in the field. Essential oils detected by gas-liquid chromatography included nine components in the case of the regenerated flowers and six and ten components in the case of stage 3 and stage 4 flowers grown in the field, respectively. There were four common components, namely, 1-hepten-3-ol, benzyl alcohol, phenethyl alcohol and cinnamyl alcohol. In the regenerated flowers, a single component, phenethyl alcohol, was a major constituent (75%), whereas two compounds, phenethyl alcohol (stage 3, 55%; stage 4, 48%) and cinnamyl alcohol (stage 3, 23%; stage 4, 29%) were the major constituents in the case of flowers grown in the field. Four and five other components were specific to flowers regenerated in vitro and field-grown flowers, respectively.Abbreviations BA 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - ABA abscisic acid - GA₃ gibberellic acid - ACC 1-aminocyclopropane-1-carboxylic acid - ethephon (2-chloroethyl)phosphonic acid - MS medium Murashige and Skoog's medium - GLC gas-liquid chromatography - GC-MS gas chromatography-mass spectrometry - FW fresh weight     

Osservazioni Sull'Assunzione Dell'Acqua Durante le Prime Fasi Di Germinazione Di Semi Di Pinus Pinea L

Abstract

Water assumption during the early germination stages in «Pinus pinea» L. seeds. – Germination of «Pinus pinea» L. seeds in several conditions has been studied. The main results attained are the following: 1) The micropyle appears to be the only water way into the seed, to start root growth. When this route is prevented and water is absorbed only by the seed surface, the embryo grows into a big cotyledon-hypocotyl complex, where the radicle is still blocked in the embryonic stage; 2) The micropyle appears to be involved also in gas exchange processes during germination.     

Inibizione della nodulazione radicale nel pisello meteor come conseguenza del trattamento nictofasico intermittente con luce rosso-estrema

Abstract

INHYBITION OF NODULATION IN METEOR PEA, BY NICTOPHASIC TREATMENT WITH FAR-RED RADIATION. — A remarkable inhybiting effect of far-red light (given to the aerial part of the plants as a flash befor and during the nictophase) on Pea root nodulation, has been achivied through some preliminary experiments. The relations between irradiated aerial parts and the activities of the underground organs in general, are being studied in the picture of photo-chromoperiodism.

Relations with the action of gibberellic acid (GA) are preliminary attempted. The inhibiting action of GA is far less striking in comparison with that of far-red radiation. Kinetin favores, at some extent, the nodulation process.     

Production of the new antimalarial drug artemisinin in shoot cultures of Artemisia annua L.

From aseptically grown Artemisia annua plantlets, shoot cultures were initiated. Using different concentrations of auxine, cytokinine and sucrose, a suitable culture medium was developed, with respect to the growth of the shoots and their artemisinin accumulation. Nitrate concentration and conductivity appeared to be suitable growth parameters. The artemisinin content was measured gas chromatographically. The shoot cultures were maintained in the developed standard medium, consisting of a half concentration of MS-salts with vitamins, 0.2 mg l^-1 BAP, 0.05 mg l^-1 NAA and 1% sucrose. The growth of the shoots and the artemisinin content remained stable for a longer period. They showed considerable photosynthetic activity and generally contained ca. 0.08% artemisinin on a dry weight basis. The highest artemisinin content found was 0.16% in the above mentioned standard medium, but also on the same medium with 0.5% sucrose. Attempts were made to further improve the artemisinin production by varying the medium composition through addition of gibberellic acid or casein hydroly-state; by omitting plant growth regulators; by precursor feeding, i.e. mevalonic acid; by influencing the biosynthesis routing through inhibition of the sterol synthesis by miconazole, naftifine or terbinafine; by changing gene expression with 5-azacytidine or colchicine; and by elicitation, using cellulase, chitosan, glutathione or nigeran. Enhanced artemisinin production was found with 10 mg l^-1 gibberellic acid, 0.5 g l^-1 casein hydrolysate, 10 mg l^-1 or 20 mg l^-1 naftifine. Relative increases of 154%, 169%, 140% and 120% were found, respectively. Other additions caused the growth to cease and the artemisinin contents to drop.Abbreviations BAP benzylaminopurine - DW dry weight - FW fresh weight - GA₃ gibberellic acid - MS Murashige & Skoog basal medium - NAA naphthaleneacetic acid