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.     

In vitro regeneration of the tropical multipurpose leguminous tree Sesbania grandiflora from cotyledon explants

Summary A system using cotyledon pieces as explants and a BAP/NAA containing medium was developed for in vitro mass propagation of Sesbania grandiflora, a tropical nitrogen-fixing leguminous tree. The age and the lighting conditions of seedlings providing the explants were shown to be critical factors for both bud induction and bud elongation. Optimal choice for an efficient and reproducible bud induction process consisted of dark-grown seedlings, 24/36 h-old-post-imbibition, that yielded up to 96% of explants producing more than 30 buds each, after one week in culture. Bud development occurred throughout a direct organogenesis pathway, from the proximal and adaxial cut surface of the explants as proved by histological studies. Additional sites of regeneration were also obtained after wounding on the epidermal surface of explants, suggesting a large distribution of regenerative cells all along the explants. Bud elongation, i.e. stem differentiation and leaf growth, was improved by bud isolation from cotyledon explants and their further subculture in liquid bud elongation media for one week. Rooting was obtained on an auxin medium after 3 weeks and plants were established in soil with 92% success.Abbreviations BAP 6-BenzylAminoPurine - NAA a-Naphthalene Acetic Acid - IBA Indole-3-Butyric Acid - IAA Indole-3-Acetic Acid - GA3 Gibberellic Acid - MS Murashige and Skoog (1962) medium     

GA,ABA, phenol interaction in the control of growth: Phenolic compounds as effective modulators of GA-ABA interaction in radish seedlings

Abscisic acid, a potent growth inhibitor inhibits hypocotyl growth ofRaphanus sativus seedlings. Phenolic compounds,viz., trans-cinnamic acid, chlorogenic acid, ferulic acid, salicylic acid, tannic acid and quercetin when applied with ABA, antagonize ABA action and restore normal seedling growth. Gibberellic acid promotes hypocotyl growth and on combined application with ABA, the ratio of their concentrations determines the course of the resultant growth. This interaction can be modulated by phenolic compounds. Phenolic compounds in low concentrations when present together with GA and ABA, favour GA-induced growth by antagonizing the inhibitory influence of ABA. The inhibitory action of abscisic acid on a wide range of growth processes is so far known to be reversed only by growth promoting hormones,viz., IAA, GA and cytokinins. Antagonistic action of phenolic compounds towards ABA, and increasing the action of GA when present together with GA and ABA, establishes a dual role to this class of compounds; balancing the effect of both growth promoting and growth inhibiting hormones. Part I.     

Cloning and Characterization of <i>EuGID1</i> in <i>Eucommia ulmoides</i> Oliver

Gibberellic acid controlled the key developmental processes of the life cycle of landing plants, and regulated the growth and development of plants. In this study, a novel gibberellin receptor gene EuGID1 was obtained from Eucommia ulmoides Oliver. The cDNA of EuGID1 was 1556 bp, and the open reading frame was 1029 bp, which encoded 343 amino acids. EuGID1 had the homology sequence with the hormone-sensitive lipase family. Amino acid sequence alignment confirmed EuGID1 protein had the highest homology with the GID1 protein of Manihot esculenta. EuGID1 was located in the nucleus and cell membrane and had expression in four plant organs. Overexpression of EuGID1 in transgenic Arabidopsis plants promoted plant elongation and increased siliques yield.     

Contributo alla flora del valdarno superiore

Summary

Considering variously aged individui of the short-day plants Chenopodium amaranticolor Coste et Rein, and Perilla ocymoides Lour. var. nanckinensis Voss., researches were carried out concerning differences in photoperiodic behaviour due to ontogenetical progress and other conditions.

Experiments showed that plants behave photoperiodically in a quantitative different manner in relation to age degree. In connection with ontogenetic progress there is a lowering in the minimal anto-inductive number of fotocicli (short day); if a series of fotocicli is given, the minimal duration of the photophase, as well as the need of light intensity, are also lowered. Chenopodium plants, cultivated during 14 weeks in long days, shows — as an extreme manifestation — the ability to form inflorescence primordia even only after one photoinductive ciclus treatment. (i. e. one 16-hours nictophase). Perilla plants cultivated during 16 weeks in long days (more aged plants were not taken into consideration) are able to form inflorescence primordia after 3 photo-inductive cicli (12-hours nictophases). Also these plants, nevertheless, form infl. primordia by means of the action of one nictophase solely, provided this nictophase is cospicuosly prolonged beyond the critical duration; the nictophase shows, in this case, a florigenic action (of particular character: see below) that goes further quantitatively in connection with the exceeding prolongation of conditions of darkness beyond the critical point. The samething may be said for Chenopodium 10-weeks old plants (that do not form infl. primordia with one nictophase of 16 hours). All these tests are able to form infl. primordia in continuous darkness and, always in dark conditions, form possibly flower and liable seeds. Young individui do not behave as aged ones. The age is not the only requisite that grants to the plants this behaviour; such characteristics depends also on the general conditions of nutrition, etc.; therefore, according to the conditions of culture, plants will have the same prerogatives at differents ages.

As to the problem of mechanism under which the infl. primordia formation and flowering is afforded in continuous darkness, and in general in connection with the causes determining the variations in photoperiodical behaviour with aging, many possibilities are discussed. Special importance has been granted to the fact that the individuus, with aging, becomes by and by anto-autonomous (at various degrees) owing to the slow accumulation of eu-florigenic materials formed in long-day conditions.

The anto-autonomous plants are able to form infl. primordia, in darkness, even leaveless (plants deprived of leaves before the treatment): storage occurs expecially in the stem or stock; the storage eu-florigenic substances may be considered simply trophic substances, but of a certain composition and quantity.

The anto-autonomous plant, even at a high degree, do not flower in long-day condition owing to a mechanism of pure photoperiodic anto-inhybition. In continuous darkness it flowers essentially owing to the euflorigenes reserves (a positive factor) and — at the same time — owing to the inability of leaves and stem parenchims to actualise any antiflorigenic process (negative factor).

Many problems are object of discussion and will be bound to further experimental work. Thus the behaviour of leaves in continuous darkness or in a dark-period prolonged beyond the critical point. The leaves of aged plants do not seem to remain, in this case, merely actionless in as much as it concerns the developmental processes.     

Impiego delle sezioni di coleoptile di alcune varietà italiane di frumento nel dosaggio biologico di sostanze promotrici ed inibitrici della crescita

Abstract

Growth response of coleoptile sections from four Italian cultivars of wheat to some growth regulators.—The following Italian wheat varieties were used to obtain the coleoptile sections used throughout the experiments: Funo, S. Pastore, Abbondanza, Generoso.

The growth substances tested were Indolacetic acid (IAA), Abscisic acid (ABA), Kinetin and Gibberellic acid.

The colcoptile response of each variety was tested with three different concentrations for each growth regulator in combination with two sucrose concentrations and three different pH levels.

The experiments indicated that the coleoptiles from the variety « Funo » react linearly to incresing IAA and ABA concentration resulting the best one to be used in this bioassay.     

Blockade des Gibberellinsäure-Transports in Hypocotylsegmenten durch Trijodbenzoesäure. Zugleich ein Neuer Agarblocktest auf Gibberelline

Summary Gibberellic acid (GA) was incubated in agar blocks, transported through hypocotyl sections of sunflower plants, and collected in acceptor blocks of plain agar. The amount of GA transported through the sections was tested with dwarf pea plants using a new test method in which the acceptor block was applied directly to the test plant. The GA transport was significantly lower through hypocotyl section from plants which had been treated with triiodobenzoic acid (TIBA) before isolation of the sections. TIBA inhibits the transport of GA.

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Mit 1 Textabbildung

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Herrn Prof. Dr. Dr. h. c.Hermann von Guttenberg zum 80. Geburtstag.     

Characterization of the first dominant dwarf maize mutant carrying a single amino acid insertion in the VHYNP domain of the <Emphasis Type="Italic">dwarf8</Emphasis> gene

The “green revolution” involving mainly wheat and rice was based on the use by breeders of semidominant mutations involved in the signal transduction pathway of Gibberellin (GA). In particular, mutations in the Reduced height (Rht) gene of wheat have been used to reduce plant height and consequently to avoid storm damage and lodging. These genes have been cloned and they encode for DELLA proteins which contain an N-terminal DELLA and a VHYNP domain essential for GA-dependent degradation of these proteins. In maize several mutations have been isolated which affect gibberellin biosynthesis and perception and in particular, mutations in Dwarf8 (D8) gene cause a severe dwarfing phenotype. D8 gene has been identified as an orthologue of Rht (Reduced height), Slr1(Slender rice 1) and Gibberellic Acid Insensitive (GAI) genes, this latter is a negative regulator of GA response in Arabidopsis. In this work, for the first time, we isolated and characterized a single amino acid insertion in the VHYNP domain of D8 maize gene causing the appearance of a dominant dwarf mutation. This spontaneous mutation, named D8-1023, showed a phenotype which is less severe in comparison with the other D8 mutants previously isolated which have modifications in the DELLA domain. This mutant appears to be an useful tool either to study the mechanism of GA-modulated growth in plants or to lower the height of maize tropical germplasm for breeding purposes.     

Diversity of Mechanical Architectures in Climbing Plants: An Evolutionary Perspective

Mechanical architectures of a wide range of climbing plants are reviewed from a wide phylogenetic range and evolutionary contingencies. They include an herbaceous lycopod (Lycopodiaceae) - a woody tropical liana (Apocynaceae), temperate climbers, herbs and shrubs (Ranunculacae), and two representative climbing palms (Arecoideae, Calamoideae). Trends in mechanical properties during development are reviewed and interpreted via changes in anatomical development of the stem and type of connection to host supports. The results indicate that there are some biomechanical features common to diverse climbing plants including (1) phases of relatively rigid stem growth where the climbing stem has to span between supports and (2) a mechanism to achieve greater compliancy towards the base or at points where the slender climbing stem is at risk from excessive mechanical stress. Evolutionary contingencies such as basal plesiomorphic constraint, complexification, simplification and developmental loss can drastically influence ways in which different plants have evolved different biomechanical climbing architectures. Two key developmental features controlling the biomechanics of the climbing stem are (1) the presence/absence of secondary growth and (2) the number, complexity and coordination of development of primary or secondary tissues with varying mechanical properties. Recent research has suggested that evolution of specialized climbing architectures can canalize subsequent evolution of alternative growth forms. The results suggest that the origin and type of climbing architecture can be heavily influenced by ancestral growth forms and architectures. Despite the extremely complex patterns of plant growth form evolution involving escapes to and from more specialized or simpler bauplans, selective pressure towards non-self-supporting growth forms is a remarkably persistent and iterative feature of growth form evolution in land plants.     

Effect of sand culture and sodium chloride on growth physical structure and organic acid metabolism inBryophyllum pinnatum

Summary Bryophyllum pinnatum, a classical example of Crassulacean Acid Metabolism, was grown in sand and soils as well as in increasing concentrations of chloride and sulphate ions to test the effect of rooting medium and salts on growth, physical structure of leaves and on organic acids. Plants grown in sand medium show fewer and smaller stomata, a shorter and profusely branched root system and also a decrease in organic acid metabolism, as compared with plants grown in garden soil. This indicates that the subtratum plays an important role in controlling growth, physical structure of leaves and Crassulacean Acid Metabolism. The presence of chlorides tends to produce thicker leaves which have more organic matter and less moisture. Increase in NaCl-concentration retards growth and also affects CAM. In plants treated with 0.04M NaCl there is a stimulation in organic acid synthesis which results in higher TAN values. Another interesting observation is that the development of a succulent habit is due to effect of chlorides and not by sulphate or sodium ions.     

Effect of gibberellic acid on the ion ratios in a dwarf maize mutant (Zea mays L. d1)

The effect of gibberellic acid (GA₃) on ion ratios in a dwarf maize mutant (Zea mays L. d₁) exhibiting normal growth after hormone treatment has been investigated by electron microprobe analysis. Gibberellic-acid treatment increased the ion content in chloroplasts and vacuoles whereas no change of the ion content was found in the cytoplasm. The relation of these observations to the action of the hormone is discussed.Abbreviation GA₃ Gibberellic acid     

Promotion of leaf sheath growth by gibberellic acid in a dwarf mutant of rice

The mechanism of gibberellin (GA)-induced leaf sheath growth was examined using a dwarf mutant of rice (Oryza sativa L. cv. Tan-ginbozu) treated in advance with an inhibitor of GA biosynthesis. Gibberellic acid (GA₃) enhanced the growth of the second leaf sheath, but auxins did not. Measurement of the mitotic index and cell size revealed that cell elongation rather than cell division is promoted by GA₃. Gibberellic acid increased the extensibility of cell walls in the elongation zone of the leaf sheath. It also increased the total amount of osmotic solutes including sugars in the leaf sheath, but did not increase the osmotic concentration of the cell sap, due to an accompanying increase in cell volume by water absorption. In the later stage of GA₃-induced growth, starch granules completely disappeared from leaf sheath cells, whereas dense granules remained in control plants. These findings indicate that GA enhances cell elongation by increasing wall extensibility, osmotic concentration being kept unchanged by starch degradation. Received: 28 August 1997 / Accepted: 16 October 1997     

Embryological studies on Indian Taraxacum Weber. Embryo sac,endosperm and embryo

Abstract

The present paper deals with the embryological studies of ten species of Taraxacum, out of which nine polyploid species are apomictic and one diploid species T. wallichii shows normal sexual behaviour. Occasional formation of normal megaspore tetrads and triads are observed in tetraploid and triploid species.

Autonomous development of endosperm from the secondary nucleus seems to be the rule. The growth of endosperm is relatively slow.     

The double cloak of invisibility: phenotypic plasticity and larval decoration in a geometrid moth,Synchlora frondaria,across three diet treatments

Abstract 1. Crypsis is one of the main defences that insects use to avoid predators, and both the juveniles and adults of many geometrid moths are remarkable in their ability to blend into different host backgrounds. The larvae of Synchlora frondaria have two methods to achieve crypsis: phenotypic plasticity in colouration that enable them to hide more effectively on their host plants, and a self‐decorating behaviour whereby the larvae camouflage themselves with materials from their host plants. 2. Larvae of Synchlora frondaria reared on three different host plants showed systematic differences in relative growth rate, survivorship and larval colouration. 3. Larval colouration varied across diet treatments in a way that was consistent with diet‐induced phenotypic plasticity, and larvae also exhibited characteristic decorating behaviour on all three hosts. 4. Larvae showed highest survivorship on Heterotheca subaxillaris (Asteraceae), and had significantly higher relative growth rates on H. subaxillaris (Asteraceae) and Lantana camara (Verbenaceae) than on Bejaria racemosa (Ericaceae). 5. Synchlora frondaria provides an example of a species where both decorating behaviour and phenotypic plasticity in larval colouration produce a cryptic form that is remarkably responsive to its background.     

The calcifuge behaviour of Visearía vulgarís

Soil factors responsible for the inability of Visearía vulgaris to colonize or survive on calcareous soils in Scandinavia were studied using experiments with plant establishment from seeds and re-establishment of mature plants, in soils of naturally differing or artificially varied chemical properties. Limestone soil proved less suitable for re-establishment of mature plants, and establishment from seeds was not possible in this soil. The plants grown on limestone had a very low phosphorus content and displayed deficiency symptoms. Acid leptite soil and soil from the A-horizon of a dystric cambisol were suitable for plant establishment from seeds and re-establishment of adult individuals, respectively. However, growth increased significantly when pH-KCl was raised to 7.6 by adding CaC0₃. Establishment from seeds was successful in the Archaean and Ordovician limestone soils only when CaHP0₄ was added. The calcifuge behaviour of Visearía vulgaris is not due to negative effects of a high pH or a high Ca concentration in the soil. Inability to utilize the native phosphorus of such soils is the most evident explanation.     

Transformation of potato (Solanum tuberosum) cv. Mantiqueira using Agrobacterium tumefaciens and evaluation of herbicide resistance

Summary In search of establishing a system for genetic transformation of Brazilian potato cultivars, Agrobacterium tumefaciens carrying the plasmid pGV1040, was used to transform leaf discs of three cultivars of local importance, i.e., Aracy, Baronesa and Mantiqueira. This plasmid contains marker genes for resistance to kanamycin and phosphinothricin plus the gene for the enzyme -glucuronidase. A two step regeneration/selection procedure produced shoots of potato cultivar Mantiqueira with in vitro resistance to kanamycin and to phosphinothricin. After transfer to the greenhouse, the potentially transgenic plants, sprayed with the herbicide Finale^® (20% a.i.; Hoechst^®) remained green as compared to control clones that died immediately afterwards. Southern blot analysis and histochemical and fluorimetric assay for -glucuronidase indicated that the gene coding for the enzyme was integrated in the potato genome and could be expressed in potato tissues. No success was obtained for transformation of cultivars Aracy and Baronesa using this procedure.Abbreviations NAA Naphthalene Acetic Acid - BAP Benzyl-aminopurine - GA₃ Gibberellic Acid - PPT Phosphinothricin - PAT Phosphinothricin Acetyl Transferase     

Sulla stimolazione da Saccarosio della Crescita di Cotiledoni Isolati di Semi di Ricino germinanti

Abstract

The effect of sugars on growth of isolated cotyledons from germinating castor bean seeds. — The presence of sugars in the medium induces a number of biochemical and physiological changes in the cotyledons isolated from germinating castor bean seeds. In the present research, the extent and the mechanism of the effect of sugars on growth of the isolated cotyledons was investigated.

The results achieved may be summarized as follows:

• Sucrose markedly stimulates the growth (as increase of fresh weight) of the isolated cotyledons; its action is already apparent when using a 10^-2M concentration and reaches a maximum (stimulation by about 400%) for the concentration between 5.10^-2M and 1,5.10^-3M. The increase of sucrose induced growth is due in almost equal proportions to water uptake and to increase of dry weight.

• The difference (Δ P.O.) between the osmotic pressure (P.O.) of the cell sap and that of the external medium is markedly higher for the cotyledons treated with sucrose (7–8 atm.) than the Δ P.O. of cotyledons incubated in water.

• Analyses of cell contents in sugars show that sucrose is taken up by the cotyledon cells against a concentration gradient. The increase of the difference of osmotic pressure between cotyledon and the external medium is satisfactorily accounted for by this active accumulation of sugars.

• When mannitol is added to the incubating medium in addition to sucrose, the active uptake of sugar is not disturbed; but the effect of sucrose on growth decreases, and it completly disappears when mannitol concentration in the medium is such, to make the value of Δ P.O. for the cotyledons in sucrose plus mannitol equal to the Δ P.O. for the cotyledons incubated in water.

• Besides increasing the P.O. in the cotyledons, sucrose markedly accelerates the decrease of free aminoacid in the isolated cotyledons.

• Auxin (β—indolacetic acid) does not stimulate, or stimulates weakly, growth of the cotyledon incubated in water; some stimulation can be observed only when sucrose is present. Gibberellic acid stimulates growth (though to a much lower extent than sucrose) in the cotyledons in water, while its action does no longer appear when sugar is present.

The decrease of free aminoacid together with other observations, indicates an effect of sucrose on protein metabolism; however, growth stimulation by sucrose seems to depend essentially on its active accumulation - against a concentration gradient - and thuson the increase of osmotic pressure. It is thus suggested that in these tissues osmotic pressure is the most important factor in limiting growth by cell extension.     

EFFECT OF METAL TOLERANT PLANT GROWTH PROMOTING BACTERIA ON GROWTH AND METAL ACCUMULATION IN ZEA MAYS PLANTS GROWN IN FLY ASH AMENDED SOIL

The present study was undertaken to examine the effect of the application of fly ash (FA) into Garden soil (GS), with and without inoculation of plant growth promoting bacteria (PGPB), on the growth and metal uptake by Zea mays plants. Three FA tolerant PGPB strains, Pseudomonas sp. PS5, PS14, and Bacillus sp. BC29 were isolated from FA contaminated soils and assessed for their plant growth promoting features on the Z. mays plants. All three strains were also examined for their ability to solubilize phosphate and to produce Indole Acetic Acid (IAA), siderophores, and hydrogencynide acid (HCN) production. Although inoculation of all strains significantly enhanced the growth of plants at both the concentration of FA but maximum growth was observed in plants inoculated with BC29 and PS14 at low level (25%) of FA concentration. The experimental results explored the plant growth promoting features of selected strains which not only enhanced growth and biomass of plants but also protected them from toxicity of FA.