Showing papers on "Abscisic acid published in 1976"
TL;DR: Abscisic acid and 2-chloroethyl phosphonic acid act synergistically with the sucrose to enhance its induction of both total phenolics and anthocyanin, and the magnitude of this interaction depends on leaf age.
Abstract: Sucrose (0.04 to 0.12 m) induces accumulation of both total phenolics and anthocyanin in leaf discs of grapevine (Vitis vinifera L.) incubated in intermittent light. Abscisic acid (20 μM) and 2-chloroethyl phosphonic acid (60 μm) act synergistically with the sucrose to enhance its induction of both total phenolics and anthocyanin. The magnitude of this interaction depends on leaf age. Nitrate (30 mm) inhibits sucrose induction of phenolics and anthocyanin. Levels of total phenolics and anthocyanin changed independently.
306 citations
TL;DR: Determinations of endogenous ABA and DPA concentrations suggest that the ABA-hydroxylating and PA-reducing enzymes are extensively metabolizing ABA in the intact E. lobata seed.
Abstract: A cell-free enzyme system capable of metabolizing abscisic acid has been obtained from Eastern Wild Cucumber (Echinocystis lobata Michx.) liquid endosperm. The reaction products were determined to be phaseic acid (PA) and dihydrophaseic acid (DPA) by co-chromatography on thin layer chromatograms as the free acids, methyl esters, and their respective oxidation or reduction products. The crude enzyme preparation was separated by centrifugation into a particulate abscisic acid (ABA)-hydroxylating activity and a soluble PA-reducing activity. The particulate ABA-hydroxylating enzyme showed a requirement for O2 and NADPH, inhibition by CO, and high substrate specificity for (+)-ABA. Acetylation of short term incubation mixtures gave evidence for the presence of 6′-hydroxymethyl-ABA as an intermediate in PA formation. Determinations of endogenous ABA and DPA concentrations suggest that the ABA-hydroxylating and PA-reducing enzymes are extensively metabolizing ABA in the intact E. lobata seed.
112 citations
TL;DR: Results are consistent with a possible role for ABA in roots of water-stressed plants and when (S)-[2-14C]-ABA was fed to excised bean roots dihydrophaseic acid was the major metabolite formed.
Abstract: Abscisic-acid (ABA) levels in roots of bean plants exposed to a—4 bar stress in the root medium increased ca. 10fold within 1 h and 16fold by the end of the 2nd h. Several types of experiments indicated that there is no transport requirement from the shoot for the increase to occur. ABA levels in roots from pea (Pisum sativum L.) and sunflower (Helianthus annuus L.) also increased in response to a—4 bar stress, although not as dramatically as in bean. When (S)-[2-14C]-ABA was fed to excised bean roots dihydrophaseic acid (DPA) was the major metabolite formed. The levels of endogenous DPA and phaseic acid increased markedly during a 27-h stress period. These results are consistent with a possible role for ABA in roots of water-stressed plants.
109 citations
TL;DR: Changes in levels of abscisic acid (ABA) and cytokinin activity in the xylem sap of willow (Salix viminalis, L.) were followed throughout two growth cycles.
Abstract: Changes in levels of abscisic acid (ABA) and cytokinin activity in the xylem sap of willow ( Salix viminalis , L.) were followed throughout two growth cycles. Growth in spring was preceded by decreasing levels of ABA and an increase in cytokinin activity. The onset of dormancy was associated with low levels of cytokinins and high contents of ABA. A second peak of ABA was found in July which was not related to the dry weight of the sap. The main cytokinin activity in the sap was due to a zeatin riboside-like compound.
99 citations
TL;DR: Cordycepin, an inhibitor of RNA synthesis in barley aleurone cells, does not inhibit the gibberellic acid-enhanced alpha-amylase (EC 3.2.1.1.) synthesis if it is added 12 hours or more after the addition of the hormone, but the accumulation of alpha-Amylase activity can be decreased by abscisic acid.
Abstract: Cordycepin, an inhibitor of RNA synthesis in barley (Hordeum vulgare L.) aleurone cells, does not inhibit the gibberellic acid-enhanced alpha-amylase (EC 3.2.1.1.) synthesis in barley aleurone layers if it is added 12 hours or more after the addition of the hormone. However, the accumulation of alpha-amylase activity after 12 hours of gibberellic acid can be decreased by abscisic acid. The accumulation of alpha-amylase activity is sustained or quickly restored when cordycepin is added simultaneously or some time after abscisic acid, indicating that the response of aleurone layers to abscisic acid depends on the continuous synthesis of a short lived RNA. By analysis of the newly synthesized proteins by gel electrophoresis with sodium dodecylsulfate, we observed that the synthesis of alpha-amylase is decreased in the presence of abscisic acid while the synthesis of most of the other proteins remains unchanged. From the rate of resumption of alpha-amylase production in the presence of cordycepin and abscisic acid, it appears that abscisic acid does not have a measurable effect on the stability of alpha-amylase mRNA.
96 citations
TL;DR: DPA and epi -DPA were shown to be formed separately from PA and could not be inter-converted either by the extraction conditions employed or when fed to bean shoots during short term experiments, indicating that the applied abscisic acid is not metabolised in a manner identical with that of the endogenous material.
95 citations
Journal Article•
89 citations
TL;DR: In the developing seeds ABA levels correlated with growth rates, being the highest during the most active growth period of seed enlargement, and then decreasing to less than 10 ng/g fresh weight at maturity.
Abstract: Abscisic acid (ABA) concentrations and growth rates of developing soybean (Glycine max [L] Merr cv Wye) seeds and pod walls were determined from anthesis to maturation using high pressure liquid chromatographic techniques Developing soybean seeds contain up to 12,200 ng/g fresh weight of ABA compared to 330 ng/g fresh weight for pod walls In the developing seeds ABA levels correlated with growth rates, being the highest during the most active growth period of seed enlargement, and then decreasing to less than 10 ng/g fresh weight at maturity Higher levels of ABA were found to occur in the cotyledons and seed coats than the root-shoot axes at 21 days postanthesis The time required for excised root-shoot axes to initiate growth in liquid culture decreased as seed development progressed and ABA levels of the seeds declined
81 citations
TL;DR: The data indicate that abscisic acid hastens senescence of carnations largely as a result of advancing the onset of autocatalytic ethylene production.
Abstract: Abscisic acid hastened senescence of carnation flowers and this was preceded by stimulation of accelerated ethylene production. Carbon dioxide delayed the onset of autocatalytic ethylene production in flowers regardless of treatment with abscisic acid. Flowers exhibited a low and transient climacteric of ethylene production without wilting while in 4% carbon dioxide and underwent accelerated ethylene production culminating in wilting when removed from carbon dioxide. Hypobaric ventilation, which lowers ethylene to hyponormal levels within tissues, extended flower longevity and largely negated enhancement of senescence by abscisic acid. Supplementing hypobarically ventilated flowers with ethylene hastened senescence irrespective of abscisic acid treatment. Collectively, the data indicate that abscisic acid hastens senescence of carnations largely as a result of advancing the onset of autocatalytic ethylene production.
76 citations
76 citations
TL;DR: It is proposed that the function of this enzyme is to mobilise the endosperm cell wall polysaccharides as a nutrient source for the growing embryo.
Abstract: Lettuce seeds (Lactuca sativa L. cv. Grand Rapids) stimulated to germinate by gibberellin and red light produce large amounts of endo-β-mannanase. This enzyme increases markedly following radicle emergence and is capable of degrading mannose-containing polysaccharides, which are the major components of the endosperm cell wall. Non-germinated seeds contain little enzyme and under conditions where gibberellin- or red light-stimulated germination is prevented (eg. by abscisic acid or prolonged far red light) enzyme levels remain low. Cycloheximide inhibits the increase in enzyme levels when supplied to germinating seeds, but the enzyme once produced is stable in vivo in the presence of this inhibitor for at least 24h. The majority of the extractable mannanase activity is located in the endosperm and we propose that the function of this enzyme is to mobilise the endosperm cell wall polysaccharides as a nutrient source for the growing embryo.
TL;DR: The ability to synthesize ABA in response to wilting or chilling was strongly expressed in young leaves and declined with leaf age, and there was no difference between leaves in their content of the metabolites of ABA, phaseic, and dihydrophaseic acid, expressed per unit weight.
Abstract: Among the four uppermost leaves of greenhouse-grown plants of Xanthium strumarium L. the content of abscisic acid per unit fresh or dry weight was highest in the youngest leaf and decreased gradually with increasing age of the leaves. Expressed per leaf, the second youngest leaf was richest in ABA; the amount of ABA per leaf declined only slightly as the leaves expanded. Transpiration and stomatal conductance were negatively correlated with the ABA concentration in the leaves; the youngest leaf lost the least amount of water. This correlation was always very good if the youngest leaf was compared with the older leaves but not always good among the older leaves. Since stomatal sensitivity to exogenous (+/-)-ABA was the same in leaves of all four age groups ABA may be in at least two compartments in the leaf, one of which is isolated from the guard cells.The ability to synthesize ABA in response to wilting or chilling was strongly expressed in young leaves and declined with leaf age. There was no difference between leaves in their content of the metabolites of ABA, phaseic, and dihydrophaseic acid, expressed per unit weight.
TL;DR: The hypothesis that maintenance of tonoplast integrity is an important factor in the ability of plants to withstand drought is strengthened.
Abstract: The subcellular changes which occurred in sorghum leaves during increasing water stress and subsequent rewatering are described. Stomata were closed, abscisic acid levels were elevated, and the amounts of starch in the bundle sheath chloroplasts were much reduced by - 14 bars leaf water potential. Swelling of the outer chloroplast membrane, and reorganization of the tonoplast to form small vesicles from the large central vacuole, occurred by a leaf water potential of - 37 bars. Complete structural disruption of the tonoplast, as previously described for maize was not found. On rewatering, large amounts of starch reappeared within three hours. These findings strengthen the hypothesis that maintenance of tonoplast integrity is an important factor in the ability of plants to withstand drought.
TL;DR: It is concluded that abscisic acid, either applied to the seedlings or induced to increase by exposure to water shortage, was involved in the development of chilling resistance in cucumber seedlings.
Abstract: Three-day-old cucumber seedlings (Cucumis sativus L) were exposed to chilling temperatures of 2 ± 1 C for 24 h. Necrosis in the cotyledons and reduction of vegetative growth of both root and shoot became evident 6 days later Increased resistance to chilling, as indicated by the extent of overall reduction in chilling damages, was obtained through pretreatments: application of abscisic acid to the seedlings, withholding of water from the seedlings, and salinization of the root medium. We concluded that abscisic acid, either applied to the seedlings or induced to increase by exposure to water shortage, was involved in the development of chilling resistance in cucumber seedlings
TL;DR: Abscisic acid applied to the seedlings prior to chilling significantly ameliorated these injuries and development of the seedling after the exposure to chilling was impaired.
Abstract: Exposure of cucumber seedlings (Cucumis sativus L.) to chilling temperature resulted in injuries such as increased leakage of cellular materials, loss of water and wilting. In addition, the development of the seedlings after the exposure to chilling was impaired. Abscisic acid applied to the seedlings prior to chilling significantly ameliorated these injuries.
TL;DR: Hypotheses and data relevant to the possible role of hormones in plants subjected to environmental stresses are presented and discussed.
Abstract: In recent years, the involvement of plant hormones has become a subject of interest in plant water relations. The interest was initially stimulated by research into leaf ageing and plant senescence and the role of cytokinins in these processes. Plant water stress and some other stresses enhance senescence. They also bring about reduction in the levels of endogenous cytokinins. Exogenous cytokinins retard leaf senescence and may stimulate stomatal opening. Later, interest in the subject gained momentum from the various observations of the role of abscisic acid in stomatal opening. Abscisic acid brings about rapid stomatal closure, and its endogenous levels in leaves increase rapidly when plants are subjected to water stress or several other stresses. Hypotheses and data relevant to the possible role of hormones in plants subjected to environmental stresses are presented and discussed.
01 Jan 1976
TL;DR: In this article, it was shown that plant hormones play an important role in the regulation of ion transport and it may be safely predicted that recent observations will stimulate research into its mechanistic aspects.
Abstract: It is now recognized that plant hormones play an important role in the regulation of ion transport and it may be safely predicted that recent observations will stimulate research into its mechanistic aspects. This applies especially to such topics as the effect of auxin on the movement of H+ ions, the kinin-abscisic acid controlled mechanism of stomatal aperture, the stimulation of salt glands by kinetin, the abscisic acid-induced stimulation of Cl- influx in storage tissues and the effects of abscisic acid on K+ and Cl- exudation from cut ends of barley and maize roots.
TL;DR: The leaves of those tolerant to drought were shown to contain substantially more free abscissic acid, and the effect was more clearly shown by sorghum than by maize.
Abstract: SUMMARY
Abscisic acid levels were measured in turgid or wilted detached leaves from maize and sorghum seedlings. Lines, cultivars and hybrids known to exhibit different abilities to withstand water stress were compared. The leaves of those tolerant to drought were shown to contain substantially more free abscissic acid. The effect was more clearly shown by sorghum than by maize. The results are discussed in relation to the physiology of drought tolerance.
TL;DR: It is concluded that the effect which sucrose has on the ABA content of rose petals is at least partly due to its effect on changes in water deficit in the petals.
Abstract: Leafless cut Superstar roses ( Rosa hyb. ) were kept in a 1% sucrose solution. During the first few days of treatment, the abscisic acid content and the water deficit in the petals was higher in treated flowers than in controls kept in water. Later and up to the termination of the flower9s life, ABA content and water deficit values were lower in petals of sucrose-treated flowers than in controls. Water stress treatments resulted in higher water deficit values and higher ABA content of petals. An 8-day sucrose treatment following temporary water stress improved the quality of flowers and reduced the level of ABA in the petals. We conclude that the effect which sucrose has on the ABA content of rose petals is at least partly due to its effect on changes in water deficit in the petals. This happens in spite of the fact that rose petals have no stomata, and therefore, ABA is not involved in regulating water balance via the stomata.
TL;DR: Inclusion of 10-6 M ABA in the growth medium of Lemna minor L inhibited frond multiplication rate and increased dry weight and relative growth rate per frond and transfer of fronds to normal nutrient resulted in a higher growth rate than controls and a rapid decrease in accumulated carbohydrates.
Abstract: SUMMARY
Inclusion of 10-6 M ABA in the growth medium of Lemna minor L. inhibited frond multiplication rate and increased dry weight and relative growth rate per frond. Sugar and starch levels were increased over and above that expected from growth inhibition alone. Transfer of fronds to normal nutrient, after 6 days growth in 10-6 M ABA, resulted in a higher growth rate than controls and a rapid decrease in accumulated carbohydrates. Net photosynthetic rate was initially increased, but declined after 2 days growth in the presence of ABA. This decrease in photosynthetic rate is discussed in relation to the accumulation of carbohydrates. Respiration rate did not increase with higher carbohydrate levels in the presence of ABA.
TL;DR: It is suggested that one way by which ABA accelerates senescence of cut roses is by promoting petal growth and respiration, thus decreasing the carbohydrate level in the petals and triggering the chain of metabolic processes leading to aging.
Abstract: The effects of sucrose and abscisic acid (ABA) and their interaction on development and senescence of petals were studied with leafless roses cultivar Super Star. Sucrose and ABA had opposing effects on the cut flowers. Sucrose retarded and ABA promoted processes associated with senescence: wilting, increase in pH, “blueing” and decrease in protein content of petals. These opposing effects are mutually antagonized when both chemicals are applied. ABA applied to flowers cut at the bud stage, promoted the rate of petal growth (but not their final size), increased respiration and caused a decrease in sucrose and an increase in level of reducing sugars.
It is suggested that one way by which ABA accelerates senescence of cut roses is by promoting petal growth and respiration, thus decreasing the carbohydrate level in the petals and triggering the chain of metabolic processes leading to aging.
TL;DR: The degree of stomatal sensitivity to CO(2) was positively correlated with the content of abscisic acid of leaves of Xanthium strumarium grown in a greenhouse and then transferred for 24 hours or more to a cold or a warm growth chamber.
Abstract: The degree of stomatal sensitivity to CO2 was positively correlated with the content of abscisic acid of leaves of Xanthium strumarium grown in a greenhouse and then transferred for 24 hours or more to a cold (5/10 C, night/day) or a warm growth chamber (20/23 C). This correlation did not exist in plants kept in the greehouse continuously (high abscisic acid, no CO2 sensitivity), nor in plants transferred from the cold to the warm chamber (low abscisic acid, high CO2 sensitivity). The abscisic acid content of leaves was correlated with water content only within narrow limits, if at all. At equal water contents, prechilled leaves contained more abscisic acid than leaves of plants pretreated in the warm chamber. There appear to be at least two compartments for abscisic acid in the leaf.
TL;DR: The life-span of coffee seeds is extended when seeds are stored with high moisture content as mentioned in this paper, and the seeds are always higher in the dark than in the light, while the opposite combination of regulators delays germination.
Abstract: The life-span of coffee seeds is extended when seeds are stored with high moisture content. Germination in darkness is always higher than in the light. Exogenous gibberellic acid and abscisic acid inhibit germination while kinetin reverses this inhibitory effect. Low levels of endogenous gibberellin- and abscisic acid-like and high levels of cytokinin-like substances favour germination while the opposite combination of regulators delays germination.
TL;DR: In this article, a stereoselective synthesis of (±)-abscisic acid was described in which 2-cis 3-methylpent-2-en-4-yn-1-ol (2) was used to introduce the 2cis, 4-trans geometry.
Abstract: A stereoselective synthesis of (±)-abscisic acid (7) is described in which 2-cis 3-methylpent-2-en-4-yn-1-ol (2) is used to introduce the 2-cis, 4-trans geometry.
TL;DR: An investigation was conducted into the relation of ABA (cis-trans-abscisic acid) in the dormant buds of alternate bearing ;Valencia' orange (Citrus sinensis [L.] Osbeck) trees, and there was a drastic drop in t-ABA in both types of buds as spring growth approached.
Abstract: An investigation was conducted into the relation of ABA ( cis-trans -abscisic acid) in the dormant buds of alternate bearing `Valencia9 orange ( Citrus sinensis [L.] Osbeck) trees. ABA did not appear to be related to alternate bearing but t -ABA (2- trans abscisic acid) did. There was 5- to 10-fold more t -ABA than ABA in the buds. There was more t -ABA in the buds of the “on” trees than in the buds of the “off” trees, and a drastic drop in t -ABA in both types of buds as spring growth approached. Bud dormancy and readiness for growth as related to t -ABA are discussed.
TL;DR: The abscisic acid (ABA) content was determined quantitatively in the leaves from wilted and unwilted tomato plants by the use of the wheat coleoptile test and gas-liquid chromatography.
Abstract: The abscisic acid (ABA) content was determined quantitatively in the leaves from wilted and unwilted tomato plants (Lycopersicon esculentum Mill. CV. Revermun) by the use of the wheat coleoptile test and gas-liquid chromatography (GLC). Plants which have received an insufficient daily water supply for 18 days showed adaptation to wilting conditions. The plants adjust to the added amount of water by regulating their water loss through transpiration. The concentration of ABA was not higher in the leaves of plants adapted to water stress than in plants that were watered abundantly. Wilted detached leaves and leaves from rapidly wilted intact plants showed the well-known reaction by increasing the ABA level. A possible role of ABA in the early stages of the adaptation process is discussed.
TL;DR: It is concluded that ABA has no function in the regulation of dormancy in C. album seeds and the uptake of labeled hormone strongly increases during the growth of the radicle.
Abstract: In the seeds of Chenopodium album L. visible phenomena preceding the final protrusion of the radicle enable a clear distinction between the induction and the progress of growth inside the covering structures. The light-dependent induction of radicle growth is not inhibited by exogenously applied abscisic acid (ABA). Experiments with 1-14C-ABA ruled out a lack of penetration of the hormone.
However, ABA does inhibit the growth of the radicle before final protrusion. This inhibition and the uptake of 1-14C-ABA are enhanced at lower pH values, indicating absorption of the undissociated molecule. The uptake of labeled hormone strongly increases during the growth of the radicle. This increase is not merely a reflection of extra water uptake.
Seeds of different degrees of dormancy contain equallly low levels of endogenous ABA. Much higher levels of ABA in the seeds were obtained by exogenous application of the hormone but these levels stills do not prevent the breaking the dormancy by light. It is concluded that ABA has no function in the regulation of dormancy in C. album seeds.
TL;DR: Sorghum is better able to tolerate water shortage than most crops, and further studies of its physiological mechanisms should lead to a better understanding of how to provide protection for more susceptible crops.
Abstract: Artificially induced partial closure of stomata can improve the efficiency with which plants use available water; in other words, there is a fall in the transpiration: photosynthesis ratio The careful use of some metabolic inhibitors can achieve the required inhibition of stomatal opening, but properly controlled application under field conditions is difficult and metabolic inhibition of photosynthesis in the mesophyll can occur In the search for a more specific inhibitor of the activities of stomatal guard cells, most attention has been focused on abscisic acid, a hormone which appears to function as an endogenous regulator of stomatal opening External application of abscisic acid achieves a useful reduction in the transpiration: photosynthesis ratio Studies are being made of the effects of chemical analogues of abscisic acid in the search for more active compounds Another naturally occurring substance which induces stomata to close, all- trans -farnesol, has been found in water-stressed sorghum plants Sorghum is better able to tolerate water shortage than most crops, and further studies of its physiological mechanisms should lead to a better understanding of how we can provide protection for more susceptible crops
TL;DR: In this article, it was shown that in the presence of either phosphon D or β-chlorethyltrimethylammonium chloride (CCC) at 20° C there was inhibition of both GA accumulation and germination, consistent with the hypothesis that GA biosynthesis is a necessary prerequisite for the germination of chilled hazel seeds.
Abstract: When dormant hazel seeds were subjected to six weeks chilling at 5° C their subsequent transfer to 20° C resulted in the accumulation of gibberellin (GA) followed by germination. In the presence of either phosphon D or β-chlorethyltrimethylammonium chloride (CCC) at 20° C there was inhibition of both GA accumulation and germination, a finding consistent with the hypothesis that GA biosynthesis is a necessary prerequisite for the germination of chilled hazel seeds. As abscisic acid showed a strong inhibition of germination but had little effect on GA accumulation it is presumed not to have affected GA biosynthesis but to have inhibited GA action. These conclusions were supported by experiments in which the interaction of exogenous GA3 with growth retardants and ABA was tested on the germination of chilled hazel seeds. Experiments in which the embryonic axes and cotyledons of chilled seeds were incubated separately at 20° C established that GA biosynthesis de novo occurred in the embryonic axis and indicated that in the intact seed some of the GA would have been translocated to the cotyledons. The isolated cytoledons showed no GA biosynthesis de novo but gave some release of GA from one or more bound forms.
TL;DR: Bean callus was induced to form roots (tissue differentiation) and vascular nodules (cell differentiation) by lowering the ratio of auxin to cytokinin in the growth medium and phenylalanine ammonia lyase activity of the calluses was closely correlated with the amount of cell differentiation which had occurred.
Abstract: Bean callus was induced to form roots (tissue differentiation) and vascular nodules (cell differentiation) by lowering the ratio of auxin to cytokinin in the growth medium. Both types of differentiation were inhibited by the addition of abscisic acid (at concentrations greater than I muM) to induction medium. Initiation of differentiation was inhibited, but its subsequent development was not, and the inhibition was not affected by the addition of gibberellic acid. Addition of gibberellic acid (GA) alone to induction medium stimulated tissue differentiation, although cell differentiation was unaffected (30 muM GA) or inhibited (45 muM GA) and its onset was delayed at both concentrations. Root initiation was also stimulated by gibberellic acid (0.I-45 muM) at an auxin-to-kinin ratio 10 times that normally optimal for cell differentiation. The phenylalanine ammonia lyase (PAL) activity of the calluses was closely correlated with the amount of cell differentiation which had occurred, and measurement of this confirmed that gibberellic acid delayed the initiation of cell differentiation. The increase and subsequent decline of PAL and betaI leads to 3 glucan synthetase activities, normally induced by transfer to induction medium, was abolished by abscisic acid. Addition of gibberellic acid did not affect the betaI leads to 3 glucan synthetase activity.