共查询到20条相似文献,搜索用时 15 毫秒
1.
Excision of Phaseolus vulgaris L. c.v. Red Kidney abscission zone explants results in senescence, mobilization, and abscission. Because these processes take place at about the same time, there has been some question as to whether they are causally related or are occurring in an independent but simultaneous fashion. Data presented here suggest that the latter interpretation is correct. After abscission zone explants are isolated from the leaf an aging process is set into motion and a degradation of metabolites in the pulvinus takes place. During the aging process the explants also become increasingly sensitive to ethylene which in turn promotes cell separation. Indoleacetic acid, cytokinins, and coumarin appear to retard aging since both degradative processes and abscission are inhibited. However, ethylene increased abscission without increasing degradative processes indicating that abscission and senescence are independent processes occurring at the same time. 相似文献
2.
Tobacco plants ( Nicotiana rustica L.) pre-exposed to leaf dehydration, mineral deprivation, salination, or BO 33− toxicity exhibited increased resistance to subzero temperature and to reduced oxygen in the root medium. The stressed plants all showed an elevated content of leaf abscisic acid. Upon transfer of mineral deprived and salinated plants to prestress conditions, a decline in leaf abscisic acid content to prestress levels took place together with a loss of the increased resistance to subzero temperature and to deprivation of root oxygen. Treatment with abscisic acid by direct application to the leaves or by addition to the root medium improved leaf resistance to subzero temperature and to deprivation of root oxygen. A common hormone-regulation mechanism involving abscisic acid is suggested for this phenomenon of “cross-adaptation” by which a given stress confers increased resistance to other, apparently unrelated stresses. 相似文献
4.
As part of a continuing effort to elucidate the mode of action of abscisic acid (ABA) in barley ( Hordeum vulgare L. cv Himalaya) aleurone layers, we have investigated the induction of several polypeptides by ABA in this tissue. There were nine ABA-induced polypeptides as observed by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and considerably more (at least 16 spots) on a two-dimensional gel. These proteins started to show enhanced synthesis 2 to 4 hours after ABA treatment, and their synthesis continued for at least 48 hours. In vitro translation using total RNA isolated from ABA-treated aleurone layers indicated that translatable mRNA levels of these proteins essentially paralleled the levels of in vivo synthesized proteins. The most abundant of the ABA-induced proteins was a 29 kilodalton polypeptide which was also synthesized in tissue incubated without ABA. In vivo synthesis of this protein declined as ABA concentration was decreased, with 1 nanomolar ABA approaching control level. Cell fractionation experiments located the 29 kilodalton major ABA-induced protein in 1,000 g and 13,000 g pellets; most other induced proteins were in the 80,000 g supernatant. The 29 kilodalton protein appeared to be sensitive to degradation by sulfhydryl type proteases. As expected, the induction of these proteins by ABA was suppressed by gibberellic acid. Phaseic acid, the first stable metabolite of ABA, suppressed the gibberellic acid-enhanced α-amylase synthesis but was unable to induce the ABA-induced proteins. None of the ABA-induced proteins were secreted into the incubation medium. A 36 kilodalton ABA-induced protein showed cross-reactivity with antibody against a barley lectin specific for glucosamine, galactosamine, and mannosamine. 相似文献
5.
Submergence induces rapid elongation of rice coleoptiles ( Oryza sativa L.) and of deepwater rice internodes. This adaptive feature helps rice to grow out of the water and to survive flooding. Earlier, we found that the growth response of submerged deepwater rice plants is mediated by ethylene and gibberellin (GA). Ethylene promotes growth, at least in part, by increasing the responsiveness of the internodal tissue to GA. In the present work, we examined the possibility that increased responsiveness to GA was based on a reduction in endogenous abscisic acid (ABA) levels. Submergence and treatment with ethylene led, within 3 hours, to a 75% reduction in the level of ABA in the intercalary meristem and the growing zone of deepwater rice internodes. The level of GA 1 increased fourfold during the same time period. An interaction between GA and ABA could also be shown by application of the hormones. ABA inhibited growth of submerged internodes, and GA counteracted this inhibition. Our results indicate that the growth rate of deepwater rice internodes is determined by the ratio of an endogenous growth promoter (GA) and a growth inhibitor (ABA). We also investigated whether ABA is involved in regulating the growth of rice coleoptiles. Rice seedlings were grown on solutions containing fluridone, an inhibitor of carotenoid and, indirectly, of ABA biosynthesis. Treatment with fluridone reduced the level of ABA in coleoptiles and first leaves by more than 75% and promoted coleoptile growth by more than 60%. Little or no enhancement of growth by fluridone was observed in barley, oat, or wheat. The involvement of ABA in determining the growth rate of rice coleoptiles and deepwater rice internodes may be related to the semiaquatic growth habit of this plant. 相似文献
6.
Specificities of three monoclonal antibodies (15-I-C5, DBPA 1, and MAC 62) raised against the plant hormone (S)-(+)-abscisic acid (ABA) have been compared. Immunological cross-reactivities against fifteen biologically active analogs of ABA were measured. The ABA analogs were altered at one or more of four positions: the double bonds in the ring, at C-2 C-3 and at C-4 C-5, and in the oxidation level at C-1. Several analogs were optically active with chiral centers at C-1′ and C-2′. For cross-reactivity, all three monoclonal antibodies required the carboxylic acid group, and the cis configuration of the double bond at C-2 C-3 of the ABA molecule. Monoclonals 15-I-C5 and DBPA 1 required the entire ABA sidechain from the C-1 to C-1′, but these monoclonals did cross-react with analogs with the ring double bond reduced and the C-2′ methyl cis to the sidechain. Only MAC 62 recognized analogs containing an acetylene at C-4 C-5. MAC 62 had more strict requirements for the ring double bond, but gave some cross-reactivity with acetylenic analogs having a saturated ring. All three monoclonals had higher specificity for analogs having the same absolute configuration at C-1′ as (S)-(+)-ABA. This work provides new information about the spatial regions of the ABA molecule that elicit immunological recognition, and serves as a basis for future investigations of the ABA receptor using ABA analogs and anti-idiotypic antibodies. 相似文献
7.
The role of abscisic acid in the control of flower abscission in Lupinus luteus L. was examined. Using a modified extraction and purification technique, endogenous abscisic acid levels in the upper flowers of an inflorescence were found to increase markedly some days before abscission could be detected. When abscisic acid was injected into flower-bearing nodes or fed via the roots, no increase in the abscission rate was obtained at any position in the flowerhead. Application of abscisic acid to only the leaves resulted in a marked increase in flower abscission. The role of abscisic acid per se as a primary controlling factor of flower abscission in yellow lupin is questioned. 相似文献
8.
Cotton (Gossypium hirsutum L. cv LG102) seedlings raised from seeds exposed to 100 [mu]M norflurazon (NFZ) during imbibition contained reduced levels of free abscisic acid (ABA) and were visibly achlorophyllous. Exposure of untreated cotton seedlings to ethylene concentrations >1 [mu]L/L for 24 h resulted in cotyledon abscission. In contrast, exposure of NFZ-treated seedlings to concentrations of ethylene [less than or equal to]50 [mu]L/L elicited no cotyledon abscission. Application of ABA, an ABA analog, or jasmonic acid to NFZ-treated seedlings restored ethylene-induced abscission. Isolated cotyledonary node explants prepared from NFZ-treated seedlings exhibited an altered dose-response pattern of ethylene-induced petiole abscission. Endogenous levels of free IAA were unaltered in NFZ-treated seedlings. Ethylene treatment (50 [mu]L/L, 24 h) had no effect on free indoleacetic acid (IAA) levels in either control or NFZ-treated seedlings. Levels of conjugated (ester plus amide) IAA were substantially increased in NFZ-treated seedlings regardless of ethylene treatment. These results indicate that endogenous ABA plays an essential, but physiologically undefined, role in ethylene-induced cotyledon abscission in cotton. 相似文献
9.
Abscisic acid (ABA) and decanoic acid inhibited shoot elongation and floral development of Dutch iris ( Iris hollandica Hoog. cv Ideal) meristems cultured in vitro. No synergism with respect to inhibition of leaf growth between ABA and decanoic acid was observed. With monthly harvest dates, from July 10, 1981 to October 10, 1981, there was a progressive decrease in endogenous level of free ABA in `Ideal' iris bulbs. Bulbs subjected to a full set of the usual preplanting storage conditions flowered, on average, 46 days after planting versus 194 days after planting for bulbs planted directly after harvest. ABA levels at harvest were 4- to 5-fold those after the preplanting storage treatment. In general, ABA levels did not correlate well with the length of time from planting until flowering of iris bulbs. Endogenous decanoic acid levels did not follow any pattern with respect to harvest date or postharvest treatment. After the postharvest high temperature treatment, there was about a 3-fold increase in nonscale decanoic acid concentration. Decanoic acid levels, in nonscale tissue, remained high after each of the other postharvest treatments. It is concluded that there is no good evidence to support the contention that either ABA or decanoic acid is directly involved in iris bulb dormancy. 相似文献
10.
Cordycepin, an inhibitor of RNA synthesis in barley ( Hordeum vulgare L.) aleurone cells, does not inhibit the gibberellic acid-enhanced α-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 α-amylase activity after 12 hours of gibberellic acid can be decreased by abscisic acid. The accumulation of α-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 α-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 α-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 α-amylase mRNA. 相似文献
11.
Upon exposure to 2°C day/night (D/N), leaves of Solanum commersonii ( Sc) began acclimating on the 4th day from a −5°C (killing temperature) hardy level to −12°C by the 15th day. Leaves of S. tuberosum L. ( St) cv `Red Pontiac' typically failed to acclimate and were always killed at −3°C. Leaves of control (20/15°C, D/N) and treated plants (2°C, D/N) of St showed similar levels of free abscisic acid (ABA) during a 15-day sampling period. In treated Sc plants, however, free ABA contents increased 3-fold on the 4th day and then declined to their initial level thereafter. The increase was not observed in leaves of Sc control plants. Treated St plants showed a slightly higher content of leaf soluble protein than controls. In Sc, leaves of controls maintained relatively constant soluble proteins, but leaves of treated plants showed a distinct increase. This significant increase was initiated on the 4th day, peaked on the 5th day, and remained at a high level throughout the 15-day sampling period. Exogenously applied ABA induced frost hardiness in leaves of Sc plants whether plants were grown under a 20°C or 2°C temperature regime. When cycloheximide was added to the medium of stem-cultured plants at the beginning of 2°C acclimation, or at the beginning of the ABA treatment in the 20°C regime, it completely inhibited the development of frost hardiness. However, when cycloheximide was added to plants on the 5th day during 2°C acclimation, the induction of frost hardiness was not inhibited. The role of ABA in triggering protein synthesis needed to induce frost hardiness is discussed. 相似文献
12.
Abscisic acid accumulates in detached, wilted leaves of Xanthium strumarium. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% 18O 2 and 80% N 2 indicates that one atom of 18O is incorporated in the 6′-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase. Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing 18O2 indicates that one atom of 18O is present in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-stressed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggests that either (a) the oxygen present in the 1′-, 4′-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1′- and 4′-positions of abscisic acid which is converted to abscisic acid under conditions of water stress. 相似文献
14.
The influence of abscisic acid (ABA) on carbon metabolism, rate of photorespiration, and the activity of the photorespiratory enzymes ribulose bisphosphate oxygenase and glycolate oxidase in 7-day-old barley seedlings ( Hordeum vulgare L. var. Alfa) was investigated. Plants treated with ABA had enhanced incorporation of labeled carbon from 14CO 2 into glycolic acid, glycine, and serine, while 14C incorporation into 3-phosphoglyceric acid and sugarphosphate esters was depressed. Parallel with this effect, treated plants showed a rise in activity of RuBP oxygenase and glycolic acid oxidase. The rate of photorespiration was increased twofold by ABA treatment at IO −6 molar while the CO 2-compensation point increased 46% and stomatal resistance increased more than twofold over control plants. 相似文献
16.
Endogenous production of ethylene and endogenous levels of abscisic acid were measured from Hibiscus rosa-sinensis L. abscission zone explants at six stages of development: tight bud, open flower, closed flower, petal abscission, calyx abscission, and peduncle abscission. 相似文献
17.
Several lines of evidence indicate that abscisic acid (ABA) is derived from 9′- cis-neoxanthin or 9′- cis-violaxanthin with xanthoxin as an intermediate. 18O-labeling experiments show incorporation primarily into the side chain carboxyl group of ABA, suggesting that oxidative cleavage occurs at the 11, 12 (11′, 12′) double bond of xanthophylls. Carbon monoxide, a strong inhibitor of heme-containing P-450 monooxygenases, did not inhibit ABA accumulation, suggesting that the oxygenase catalyzing the carotenoid cleavage step did not contain heme. This observation, plus the ability of lipoxygenase to make xanthoxin from violaxanthin, suggested that a lipoxygenase-like enzyme is involved in ABA biosynthesis. To test this idea, the ability of several soybean ( Glycine max L.) lipoxygenase inhibitors (5,8,11-eicosatriynoic acid, 5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, and naproxen) to inhibit stress-induced ABA accumulation in soybean cell culture and soybean seedlings was determined. All lipoxygenase inhibitors significantly inhibited ABA accumulation in response to stress. These results suggest that the in vivo oxidative cleavage reaction involved in ABA biosynthesis requires activity of a nonheme oxygenase having lipoxygenase-like properties. 相似文献
18.
Quantitative analyses of abscisic acid in the elongating zone of a single maize root ( Zea mays L. cv LG 11) were performed by gas chromatography-mass spectrometry using negative chemical ion ionization. Data showed that the more abscisic acid, the slower the growth, but a large dispersion of individual values was observed. We assume that abscisic acid is perhaps not correlated only to the growth rate. 相似文献
19.
Partially purified protein extracts from maize ( Zea mays L.) embryos, whether treated or not with abscisic acid (ABA), were incubated with linoleic acid (LA) and 1-[ 14C]LA. The resulting LA metabolites were monitored by high performance liquid chromatography with a radioactivity detector and identified by gas chromatography-mass spectrometry. α- and γ-ketol metabolites arising from 9-lipoxygenase activity were the more abundant compounds detected in the incubates, although the corresponding metabolites produced by 13-lipoxygenase were also present in the samples. In addition, a group of stereoisomers originating from two isomeric trihydroxy acids (9, 12, 13-trihydroxy-10-octadecenoic and 9, 10, 13-trihydroxy-11-octadecenoic acids) are described. Important variations in the relative proportions of the LA metabolites were observed depending on the embryo developmental stage and on ABA treatment. Two new ABA-induced compounds have been detected. These compounds are present in embryos at all developmental stages, being more abundant in old (60 days) embryos. Furthermore, ABA induction of these compounds is maximum at very young developmental stages, decreasing as maturation progresses. A tentative structure for these compounds (10-oxo-9, 13-dihydroxy-11-octadecenoic acid and 12-oxo-9, 13-dihydroxy-10-octadecenoic acid) is also provided. This study revealed an early stage in maize embryogenesis characterized by a higher relative sensitivity to ABA. The physiological importance of ABA on LA metabolism is discussed. 相似文献
20.
The effect of the abiotic stress hormone abscisic acid on plant disease resistance is a neglected field of research. With few exceptions, abscisic acid has been considered a negative regulator of disease resistance. This negative effect appears to be due to the interference of abscisic acid with biotic stress signaling that is regulated by salicylic acid, jasmonic acid and ethylene, and to an additional effect of ABA on shared components of stress signaling. However, recent research shows that abscisic acid can also be implicated in increasing the resistance of plants towards pathogens via its positive effect on callose deposition. 相似文献
|