Showing papers on "Gibberellic acid published in 1970"

Multiple Forms of Amylase Induced by Gibberellic Acid in Isolated Barley Aleurone Layers

Abstract: The addition of gibberellic acid to isolated aleurone layers of barley (Hordeum vulgare L.) causes the production and secretion of four α-amylases. Two of these are stable at pH 3.7 and are not inactivated by ethylenediaminetetraacetate. The other two represent the classical barley α-amylases; i.e., they are inactivated at pH 3.7 and by reagents which from complexes with divalent metal ions. All four forms are synthesized de novo in response to the addition of gibberellic acid.

Phytochrome and hormonal control of expansion and greening of etiolated wheat leaves

Abstract: Unrolling of etiolated wheat leaf segments is stimulated by short periods of exposure to red light. Both gibberellic acid and kinetin will stimulate unrolling in the dark, whereas abscisic acid (ABA) inhibits the unrolling response to these two hormones and to red light. Exposure to 5 minutes of red light leads to a rapid increase in endogenous gibberellin levels in etiolated wheat leaves, and this increase is followed by a rapid decline. Pre-treatment with ABA inhibits the increase in gibberellin levels in response to red light, but the ihibitory effect of ABA on unrolling cannot be ascribed only to its effect on gibberellin levels. Pre-treatment with red light reduces the lag-phase in chlorophyll development when wheat leaf segments are subsequently exposed to white light; the effect of red light may be replaced by pre-treatment with kinetin, but gibberellic acid is relatively ineffective in this respect.

Comparison of endogenous gibberellins and response to applied gibberellin of some dwarf and tall wheat cultivars.

Abstract: A number of dwarf wheat cultivars of the Norin 10 type were compared with several tall forms. Applied gibberellic acid markedly stimulated the growth of seedlings of the tall cultivars but not the growth of dwarf seedlings. Several other gibberellins were also inactive when tested with one dwarf cultivar. De-embryonated grains of all cultivars formed α-amylase in response to gibberellic acid. Gibberellic acid caused an increase in soluble carbohydrates in the leaves of the tall cultivars but not in those of the dwarfs. Germinating grains, light-grown seedlings and developing stems of the dwarf cultivars contained more endogenous gibberellin-like activity than those of tall cultivars. It is suggested that the dwarf cultivars have a block to the utilisation of gibberellin in the shoot.

β-GLUCAN AND β-GLUCANASE IN BREWING

Abstract: The development of endo β-glucanase during the micro-malting of barley, with and without the addition of gibberellic acid, was compared. Results indicated that the stimulative effect of gibberellic acid on the enzyme system was of only marginal practical importance. From the assessment of the enzyme activity in a number of commercial malts it would appear that the germination time used for some malts is too short to take full advantage of the critical phase of very rapid enzyme development. The viscosity-reducing power of β-glucanase was demonstrated in miniature brewery mashing experiments and details of the progressive degradation of β-glucan by the enzyme system were analysed by gel filtration methods. The β-glucan content of a number of varieties of barley was established.

Enzymic Mechanism of Starch Breakdown in Germinating Rice Seeds: III. alpha-Amylase Isozymes.

Abstract: The formation of amylase isozymes in germinating rice (Oryza sativa) seeds was studied by isoelectric focusing on polyacrylamide gel disc electrophoresis. Time sequence comparisons of the amylase zymogram were made between extracts from gibberellic acid-treated embryoless and embryo-attached half-endosperm of rice seeds. In both cases, 4 major and 9 to 10 minor isozyme bands were detectable at the maximal stage of the enzyme induction. However, in the embryo-attached half-seeds, bands started to diminish after the 5th day of incubation, in agreement with the results of time sequence analyses of enzyme activities. Nearly identical patterns of amylase isozyme bands on a polyacrylamide gel disc electrophoresis in combination with isoelectric focusing indicate the intrinsic role of gibberellic acid in the starch breakdown in germinating rice seeds. We tentatively assign the newly synthesized enzymes to be alpha-amylases based on experimental results concerning the lability of the preparation on a prolonged treatment at pH 3.3 and the stability on heat treatment for 15 minutes at 70 C.

Cytokinin-cytokinin-Induced tuber formation Tuber Formation on Stolons of Solanum tuberosum

Abstract: Kinetin-induced tuberization of isolated stolons was investigated with regard to accumulation of labelled kinetin, starch, protein and nucleic acid synthesis. Using kinetin-8-14C, it was found that more labelled meterial appeared at the locus of tyber formation that in other parts of the stolon. Substantial accumulation was evident before visible signs of tuber formation. The basal portion of the stolon also accumulated substantial amounts of labelled material. Kinetin-treated stolons showed extensive starch accumulation which was not evident in gibberellic acid-treated or untreated stolons. Starch accumulation occurred before any visible sign of tuber formation. There was no marked differences in the ability of the apical 0.5 cm of kinetin-treated and untrated stolons to incorporate 14 C uridine into RNA and 14C leucine into TCA precipitable protein. From these results it was concluded that kinetin-induced tuber formation may not involve the synthesis of new proteins. It is suggested that kinetin may be regulating tuber formation by suppressing starch hydrolase activity and stimulating starch synthetase activity whereas gibberellic acid inhibits tuber formation by promoting starch hydrolase activity or by suppressing starch synthesizing enzymes.

Hormonal regulation of apical dominance in soybeans

Abstract: Hormonal regulation of apical dominance in soybeans is dependent on the physiological stage of the lateral buds. In 7-day-old plants the cotyledonary buds are in an active state of mitosis and the application of a single hormone, gibberellic acid (GA) is effective in releasing the buds whilst indole acetic acid (IAA) is ineffective in inhibiting the buds of decapitated plants. In 16-day-old plants in which mitosis in the cotyledonary buds had ceased, a combination of both benzyladenine (BA) and GA was required for bud growth. BA initiated mitosis and GA promoted elongation. Application of IAA to the apical cut surface of these plants was effective in maintaining the inhibition of cotyledonary buds, and this inhibition could be overcome by a direct application of BA and GA to the inhibited buds. This study has shown that the growth of the inhibited cotyledonary buds in soybeans is regulated not only by auxins but by an interaction between auxins, cytokinins, and gibberellins. The effectiveness of any one o...

Germination Control of Johnsongrass Rhizome Buds

Abstract: Field-harvested johnsongrass (Sorghum halepense (L.) Pers.) rhizomes were assayed for bud dormancy and growth po- tential under a number of experimental conditions. Natural dor- inancy was not detected in single-node rhizome pieces harvested at any time of the year. Shoot growth rates were highly variable. Kinetin, benzyl adenine, gibberellic acid, and 2-chloroethylphos- phonic acid were ineffective in enhancing germination or normaliz- ing shoot growth. Scale leaves of rhizomes had no effect on bud growth. Rhizome buds were strongly influenced by apical dom- inance and emerged shoots partially suppressed germination of adjacent buds. The optimum temperature for bud germination an(d shoot growth was approximately 30 C. Bud germination was ssuppressed at 15 C. Johnsongrass rhizomes failed to exhibit cold har(liness at any time in their life cycle.

Radioactive Gibberellin A5 and Its Metabolism in Dwarf Peas

Abstract: Radioactive gibberellin A(5) ((3)H-GA(5)) was synthesized from gibberellic acid. When it was applied to dwarf peas grown in the dark, an average of 3% was converted to another acid gibberellin within 48 hours. The biological activity of the metabolite did not account for the response to applied GA(5). GA(5) is therefore assumed to be biologically active per se.(3)H-GA(5) did not appear to form a stable complex with a macromolecule in pea shoots. When injected into dwarf pea pods, (3)H-GA(5) was readily metabolized by maturing seed to more water-soluble substances and to two other acidic compounds. This metabolism continued even throughout germination of the seed without reconversion of the metabolites to GA(5). It is concluded that "bound" GA(5) plays no part in the germination of dwarf pea seeds.

Physiology of Oil Seeds: I. Regulation of Dormancy in Virginia-Type Peanut Seeds

Abstract: The germination and ethylene production by dormant Virginia-type peanut seeds were observed in relation to phytohormone treatments that could conceivably release the dormancy of these seeds. A comparison was made between the effects of these treatments on the less dormant apical seeds and the more dormant basal seeds. Indole-3-acetic acid did not stimulate ethylene production by, or germination of, the dormant seeds to any extent. Gibberellic acid at 5 x 10(-4) M stimulated ethylene production by apical seeds to 17 millimicroliters per hour and germination to only 40% above the control. The more dormant basal seeds were affected even less by gibberellic acid than the seeds. Ethylene gas at 8 microliters per liter stimulated germination to 85% above the control for both apical and basal seeds. At this ethylene concentration the physiology of the more dormant basal seeds was altered, so that they behaved in a manner similar to the inherently less dormant apical seeds. 2-Chloroethylphosphonic acid at 10(-3) and 5 x 10(-4) M provided results similar to ethylene gas. Both apical and basal seeds germinated 100% at 48 hours. Among the phytohormones tested in this study, ethylene gas produced the greatest germination at low concentrations, and it appears must directly related to initiating the reactions required for converting the quiescent cells to an active state of growth.

α-amylase-isozymes in gibberellic-acid-treated barley half seeds.

Abstract: The presence of multiple forms of α-amylase in gibberellic acid-treated embryoless barley half-seeds was demonstrated by separation on diethylaminoethyl-Sephadex and isoelectric focusing polyacrylamide gel disc electrophoresis. Two major α-amylase fractions (A and B), each consisting of two to three isozyme components, were purified. α-Amylase fractions A and B were distinguishable in their reaction patterns. The optimal pH of fraction A α-amylase was found to reside in the acidic side (pH 5.0), as was determined by analyzing the reducing sugars formed as well as the paper chromatographic detection of reaction products. At neutral pH, 6.9, fraction A exhibited weak amylolytic activity in forming maltose. The α-amylase activity in fraction A was markedly stimulated by heat treatment (70 C/15 minutes). Fraction B, constituting a major part of amylases in the endosperm extract, was also found to be composed of α-amylase, as evidenced by the loss of enzyme activity upon allowing fractions A and B to stand at pH 3.3 for a prolonged period. The possible physiological function of the two different types of α-amylase in the carbohydrate breakdown of barley seeds is discussed.

Increased Ribonucleic Acid Polymerase Activity Associated with Chromatin from Internodes of Dwarf Pea Plants Treated with Gibberellic Acid

Abstract: Gibberellic acid increases the level of RNA polymerase associated with chromatin isolated from expanding internodes of light-grown, dwarf pea plants (Pisum sativum L.), without a detectable increase in the amount of DNA template available.

Acceleration and delay of ripening in banana fruit tissue by gibberellic acid.

Abstract: Dipping of whole banana fruit in aqueous solutions of gibberellic acid (GAs) at concentrations of 10-L 10-2M delays ripening. In contrast, treatment of banana fruit slices by vacuum infiltration with GA3 at concentrations ranging from 10-6 to 10-2M accelerates ripening. These contrasting effects appear to be related to the differences in distribution of GA3 in the tissue, resulting from the two methods of treatment.

Axenic culture of meristem tips of Rosa multiflora

Abstract: Excised shoot apices (0.6 or 1.0 mm long) of Rosa multiflora were grown in axenic culture on defined media including auxins, gibberellic acid and cytokinins. In the presence of zeatin (10(-8)-10(-7)M) and 6-benzylaminopurine (10(-7)-10(-6) M) apices grew into plantlets but two other cytokinins, kinetin and 6-(3-methylbut-2-enyl)aminopurien, were ineffective. Auxins or gibberellic acid were either inhibitory or had no effect on differentiation.

Regulation of leaf form in Centaurea solstitialis L. I. Leaf development on whole plants in sterile culture

Abstract: Some factors controlling heteroblastic development in Centaurea solstitialis L. are reported and discussed. Whole plants were grown in sterile culture, and it was demonstrated that the level of available carbohydrates partly accounts for the heteroblastic series. Growing plants in sterile culture supplemented with gibberellic acid prevented the development of the adult leaf form, whereas Centaurea plants grown in media supplemented with Cycocel (CCC) formed adult leaves earlier than plants growing in media lacking CCC. When transferred to a GA-supplemented medium, plants already producing the adult leaf undergo transition to flowering, and all new leaves develop as the juvenile form. It is proposed that the heteroblastic series is in part regulated by the endogenous levels of gibberellins.

Export of photosynthate affected when leaves are pretreated with growth substances.

Abstract: SEVERAL investigators have shown that cytokinins are strong mobilizing agents1–3. For example, a spot of cytokinin on a leaf can attract such substances as amino-acids from adjacent untreated tissues, and treatment of fruits4,5, shoot tips6, or expanded leaves7 increases movement of photosynthate into the treated area. Gibberellic acid also enhances movement of assimilates into the treated area, but the growth retardant CCC ((2-chloro-ethyl)-trimethylammonium chloride) causes a decrease in the mobilizing power of the treated area4,6. We are not aware, however, that leaves on intact plants have ever been pretreated with growth regulators to study the effect on the export of photosynthate from the treated leaves.

Effects of growth substances on the absorption and transport of iron plants

Abstract: The effects of a number of growth substances on the absorption and translocation of iron were studied in bean plants. Gibberellic acid application to the trifoliate leaf enhanced absorption of Fe applied to the primary leaf. 2-Chloroethyltrimethylammonium chloride increased absorption by the primary leaf while 6-furfurylaminopurine (kinetin) increased the transport of Fe from the primary leaf to other parts. When the roots were pretreated with gibberellic acid, the absorption of Fe by the primary leaf and subsequent transport to the trifoliate leaves were increased. Triiodobenzoic acid reduced the absorption and transport of Fe.Absorption of Fe by roots and transport to other parts were increased by pretreatment of the roots with gibberellic acid, 2-chloroethyltrimethylammonium chloride or N,N-dimethylaminosuccinamic acid for 3 days. An increase in the transport to other parts of Fe absorbed by roots was obtained when roots were exposed to the growth substances following Fe absorption.Absorption and transport of Fe in corn plants were much less than those of Rb and phosphate. Absorption and transport of Fe were greater in plants with decorticated roots than in those with intact roots. N,N-Dimethylaminosuccinamic acid significantly promoted the transport of root-absorbed Fe to the shoots of corn plants.

Effects of Stratification, Gibberellic acid and Germination Temperature on the Germination of Betula nana

Abstract: Experiments were carried out with three seed lots of Betula nana collected in 1967 from different localities in Norway. Seeds were stratified for 0-20 days in dark at +2-+3 °C on filter papers moistened with distilled water, or treated with solution of GA3 for 24 h at room temperature, and then moved into special germination boxes that were placed in different temperature conditions. All the seed lots had conditional dormancy. Quantitatively, the dormancy was different in the different seed lots (pronenances), but there were no qualitative difference in the reaction to stratification gibberellic acid and to germination temperature. Differences between seed lots may have been due to different stage of seed development. The dormancy was deepest at low temperatures(12 and 15°C) decreasing gradually with increasing temperature (to 24 °C). The dormancy was effectively broken by a short stratification (from 5 to 15 days), and by treatment with gibberellic acid. The deeper the dormancy and the lower the germination temperature the longer the stratification that was needed for maximum germination. Similarly, the concentration of GA3 needed for maximum germination increased with decreasing temperature and with increasing dormancy.

Regulation of Bud Rest in Tubers of Potato, Solanum tuberosum L: VI. Biochemical Changes Induced in Excised Potato Buds by Gibberellic Acid.

Abstract: The rest period of the potato tuber was studied in relation to certain biochemical changes that are induced by gibberellic acid (GA(3)). The concentration of reducing sugars in excised plugs with buds treated with 10(-4)m GA(3) decreased in the first 4 hours after treatment and then rapidly increased up to 70 hours. The pattern in control buds was similar, but the changes occurred more slowly. The response to GA(3) is temperature-dependent and is not limited to any particular tissue of the tuber. The concentration of reducing sugars in excised buds increased proportionally to the log of the concentration of GA(3) in a range from 10(-8) to 10(-4)m. At 10(-3)m, GA(3) slightly inhibited production of reducing sugars. Malonate inhibits the initial decrease and the subsequent increase in reducing sugars in control buds, but not the increase induced by GA(3).Total protein in buds was not influenced by 10(-4)m GA(3) over a period of 40 hours, nor did activity of alpha-amylase increase significantly until 20 hours after beginning of treatment. Invertase activity was present initially and, in the presence of GA(3), increased after 20 hours. GA(3) had no effect on starch phosphorylase activity, which was always present and remained steady over the 20-hour test period.In short term experiments the rate of protein synthesis and synthesis of specific protein fractions were not affected by 10(-4)m GA(3), as measured by the incorporation of l-phenylalanine-U-(14)C or by experiments with (14)C- and (3)H- labeled l-phenylalanine or l-leucine.

The hormonal regulation of bud outgrowth in Phaseolus vulgaris L.

Abstract: Aqueous solutions of indole acetic acid, kinetin, gibberellic acid and abscisic acid were applied singly and in combination to the decapitated stem stump of Phaseolus seedlings. Application of indole acetic acid will not completely replace the intact stem apex with regard to the inhibition of lateral bud extension. The greatest inhibition of bud growth is obtained when indole acetic acid is applied in combination with both kinetin and abscisic acid. Treatment with gibberellic acid causes massive bud growth even in the presence of indole acetic acid, kinetin and abscisic acid. Although both abscisic acid and kinetin have only a slight promoting effect on bud outgrowth when applied singly, these hormones will modify the effects of indole acetic acid and gibberellic acid.

Floral Inducing Extract from Xanthium

Abstract: Flower formation was initiated in Lemna by acetone extracts of flowering cocklebur (Xanthium). These extracts also initiated flower formation in Xanthium when they were supplemented with gibberellic acid. No flower formation was initiated in dluckweed (Lemna) or Xanthium by extracts from vegetative Xanthium. Extracts from vegetative plants supplemented ivith gibberellic acid did not initiate flowers in Xanthium or Lemna.

Grafting and gibberellin effects on the growth of tall and dwarf peas

Abstract: Tall peas var. Alaska and dwarf peas var. Progress No. 9 were grafted onto their own roots or reciprocally grafted to determine the rootstock effect on the growth of the stem. In all cases the grafted stems grew the same as their ungrafted controls regardless of which rootstock they were grown on. When similarly grafted plants were supplied with gibberellic acid, good graft unions did not inhibit its translocation. This evidence supports the thesis that the mechanism controlling stem growth in peas is located in the stem and that the roots have no direct control over this mechanism.

Patterns of development of glycosidase activities in the pea epicotyl

Abstract: Rates of hydrolysis of α- and β-linked glucosides and galactosides were compared in reaction mixtures containing nitrophenol derivatives, maltose, or cellobiose as substrates, plus enzyme derived from various parts of the third internode of the pea epicotyl. β-Glucosidase activity (EC. 3.2.1.21) per unit fresh weight, protein, or DNA was concentrated in meristematic tissues (plumule and hook) and nearly absent from adjacent growing and maturing regions in the internode. The other glycosidase activities showed no such specific localization. β-Glucosidase was also the only one of these enzymes that increased in specific activity in the decapitated epicotyl after treatment with indoleacetic acid. The increase (about twofold in 2 days) occurred if cell division was evoked at the same time. Treatment with gibberellic acid had little effect on any glycosidase activity. It is concluded that β-glucosidase activity may have been especially useful in cells during or shortly after cytokinesis, but none of the glycos...

Response of cereal grains to gibberellic acid

Abstract: Aleurone cells of oats produce significantly less α-amylase than the aleurone cells of rye, wheat or barley after treatment with gibberellic acid (GA3). Furthermore, excised embryos from oats, rye, wheat or barley are more efficient than exogenous gibberellic acid in catalysing the production of α-amylase in oats endosperms. Enzymic modification of the endosperm of oats, as distinct from the other cereal grains, is associated with rapid elongation of the scutellar apex under the aleurone cells.

Effects of 2-Chloroethylphosphonic Acid and Gibberellic Acid on Sex Expression and Growth of Pumpkins

Abstract: Treatment of pumpkin plants with 2-chloroethylphosphonic acid (CEPHA) induced a greater production of female flowers, shorter internodes and earlier fruit set while treatment with gibberellic acid (GA) induced a greater production of male flowers, longer internodes and later fruit set. Although CEPHA induced the production of a greater number of female flowers, the bulk of the flowers aborted and only a slight increase in the number of fruits per pumpkin plant occurred. The addition of equal concentrations of CEPHA and GA resulted in pumpkin plants with longer internodes and a greater number of female flowers than the untreated plants, although GA partially overcame the effect of CEPHA. The mode of action of CEPHA and GA on sex expression is discussed.

Growth and flowering of Lemna paucicostata II. Role of growth regulators

Abstract: Lemna paucicostata HEGELM., a short-day plant, can be induced to flower under long days by provision of cytokinins in the medium. Of several cytokinins tested, zeatin and 6-benzylaminopurine are the most potent. They are effective when added in a medium containing excess of iron and thus can bring about the same affect as EDDHA. Interestingly, when both EDDHA and a cytokinin are provided together, flowering occurs even in the medium containing normal level of iron. Other cytokinins such as SD 8339, kinetin and 6-(δ,δ-dimethylallylamino)-purine are also effective in medium containing a slightly higher level of ferric citrate. In contrast to cytokinins, indole-3-acetic acid and gibberellic acid are not only ineffective by themselves, but even nullify the inductive effect of cytokinins on flowering. Growth retardants such as CCC and abscisic acid have been found to inhibit flowering at high levels.