首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
Abstract. Aging of chloroplasts both in vivo and in vitro causes a considerable loss in the 2,6-dichlorophenol indophenol (DCPIP)-Hill reaction with water as electron donor. The loss can be reduced by exogenous electron donors like diphenyl carbazide (DPC). suggestive of aging-induced damage of the oxygen evolving system. Aging also brings about a considerable loss in methylviologen (MV) reduction mediated by Photosystem I (PS I) of chloroplasts with an ascorbate-DCPIP couple as the electron donating system.
The loss in the electron transport ability of the plastids is faster during in vitro compared to in vivo aging of the chloroplasts.
Light protects the photo-electron transport ability of chloroplasts during aging of intact leaves in contrast to its action during aging of the isolated organelles.  相似文献   

2.
A technique for collection of phloem exudate from detached leaves using 20 millimolar EDTA (pH 7.0) has previously been developed (King, Zeevaart 1974 Plant Physiol 53: 96-103). It was the aim of the present study to determine the efficiency of this technique in relation to undisturbed export from attached leaves. Paired primary leaves of bean seedlings (Phaseolus vulgaris L. cv Montcalm) were used to minimize variations in plant material. Attached leaves, exposed to 14CO2 for 10 minutes with subsequent excision of one of the leaves and collection of the exudate over a 12-hour period, showed a 25% export of total assimilated 14C from the attached versus 15% of total assimilated 14C in the form of exudation from the detached ones. Leaf excision changed the labeling pattern within the leaf, increasing% total leaf 14C-activity in the ethanolic fraction, while decreasing activity in the starch fraction, as compared to attached leaves. This was presumably caused by a lack of translocation from the detached leaves. Excision did not affect dark respiration. However, measurements of total nonstructural carbohydrates in leaf starch and neutral fractions indicated no significant differences between attached and leaves detached in EDTA. Thus, in terms of actual carbon export, and accompanying distribution of nonexported carbohydrate within the leaf, EDTA-enhanced exudation compares favorably with translocation from attached leaves.  相似文献   

3.
Flowering is a unique and highly programmed process, but hardly anything is known about the developmentally regulated proteome changes in petals. Here, we employed proteomic technologies to study petal development in rose (Rosa hybrida). Using two-dimensional polyacrylamide gel electrophoresis, we generated stage-specific (closed bud, mature flower and flower at anthesis) petal protein maps with ca. 1,000 unique protein spots. Expression analyses of all resolved protein spots revealed that almost 30% of them were stage-specific, with ca. 90 protein spots for each stage. Most of the proteins exhibited differential expression during petal development, whereas only ca. 6% were constitutively expressed. Eighty-two of the resolved proteins were identified by mass spectrometry and annotated. Classification of the annotated proteins into functional groups revealed energy, cell rescue, unknown function (including novel sequences) and metabolism to be the largest classes, together comprising ca. 90% of all identified proteins. Interestingly, a large number of stress-related proteins were identified in developing petals. Analyses of the expression patterns of annotated proteins and their corresponding RNAs confirmed the importance of proteome characterization.Electronic Supplementary Material Supplementary material is available for this article at  相似文献   

4.
5.
6.
7.
Diurnal regulation of scent emission in rose flowers   总被引:3,自引:0,他引:3  
Hendel-Rahmanim K  Masci T  Vainstein A  Weiss D 《Planta》2007,226(6):1491-1499
Previous studies have shown diurnal oscillation of scent emission in rose flowers with a peak during the day (Helsper in Planta 207:88–95, 1998; Picone in Planta 219:468–478, 2004). Here, we studied the regulation of scent production and emission in Rosa hybrida cv. Fragrant Cloud during the daily cycle and focused on two terpenoid compounds, germacrene D and geranyl acetate, whose biosynthetic genes have been characterized by us previously. The emission of geranyl acetate oscillated during the daily light/dark cycle with a peak early in the light period. A similar daily fluctuation was found in the endogenous level of this compound and in the expression of its biosynthetic gene, alcohol acetyl transferase (RhAAT). The rhythmic expression of RhAAT continued under conditions of constant light or darkness, indicating regulation by the endogenous circadian clock. However, the accumulation and emission of geranyl acetate ceased under continuous light. Our results suggest that geranyl acetate production is limited by the level of its substrate geraniol, which is suppressed under constant light conditions. The emission of germacrene D also oscillated during the daily cycle with a peak early in the light period. However, the endogenous level of this compound and the expression of its biosynthetic gene germacrene D synthase (RhGDS) were constant throughout the day. The diurnal oscillation of germacrene D emission ceased under continuous light, suggesting direct regulation by light. Our results demonstrate the complexity of the diurnal regulation of scent emission: although the daily emission of most scent compounds is synchronized, various independently evolved mechanisms control the production, accumulation and release of different volatiles. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

8.
Li L  Ng TB  Gao W  Li W  Fu M  Niu SM  Zhao L  Chen RR  Liu F 《Life sciences》2005,77(2):230-240
The activities of the antioxidant enzymes catalase (CAT) and glutathione peroxidase (GPx) in the blood and liver of the aging model induced by injection of different doses of D-gal into normal mice, and in senescence accelerated mice (SAM) of different ages, were determined. The results showed that the enzyme activities in the D-gal treated mice did not alter appreciably but the enzyme activities in blood of the SAM declined significantly with the increase in age, especially in the 9-month-old SAM. When gallic acid purified from rose flowers was used to treat the 9-month-old male SAM, it not only reinstated the activities of CAT and GPx but also significantly reduced the amount of malondialdehyde (MDA) in the liver, brain and kidney. The results demonstrated that 9-month-old male SAM represent an appropriate animal model to evaluate the antioxidant activities of natural products.  相似文献   

9.
10.
The role of abscisic acid and ethylene in the senescence of rose petals cv. Golden-Wave was examined. A rise in ethylene evolution, followed by an increase in the level of abscisic acid was observed. The presence of abscisic acid in rose petals was established, using different chromatography systems, several bioassays, and immunoassay. External application of ethylene accelerated senescence and induced a rise in endogenous abscisic acid-like activity. Application of abscisic acid promoted senescence, but suppressed ethylene production. The data suggest that the participation of these two hormones in the control of senescence is via the same pathway. The possibility of interrelationship between abscisic acid and ethylene was tested and experimental evidence in favor of this hypothesis is presented. It was suggested that ethylene affects senescence in rose petals by inducing an increase in abscisic acid activity, which in turn may control ethylene evolution, via a feedback mechanism.  相似文献   

11.
Plants emit chemically diverse volatile compounds for attracting pollinators or putting up a chemical defense against herbivores. 2-Phenylethanol (2PE) is one of the abundantly emitted scent compounds in rose flowers. Feeding experiments with l-[2H8]phenylalanine into rose flowers and subsequent analysis using gas chromatography–mass spectrometry analysis revealed the hypothetical biosynthetic intermediates to [2H8]-2PE, and the biochemical and genetic analyses elucidated the principal pathway to [2H8]-2PE. We recently found season-specific 2PE pathway producing [2H7]-2PE from l-[2H8]phenylalanine. This is a unique example where the dominant pathway to a specific compound changes with the seasons. This review focuses on the biosynthesis of floral volatiles and their regulation to adapt to the changes in the environment.  相似文献   

12.
Beta-glucosidase was partially purified from Rosa 'Hoh-Jun' petals. The enzyme was highly specific for such beta-D-glucopyranosides as 2-phenylethyl beta-D-glucopyranoside. The optimal activity was observed at pH 6.0 and 35 degrees C. The enzymes were composed with two proteins (160 and 155 kDa) by blue native-PAGE, and were classified in a family 1 glucosidase based on LC-MS/MS analyses.  相似文献   

13.
The effects of oleate, spermine and chlorpromazine were assayed in the presence or absence of 0.15 M KCl on the translocation of phosphatidate phosphohydrolase activity from cytosol to endoplasmic reticulum membranes in liver homogenates obtained from rats aged 1, 30, 60, 180 and 360 days. Marked age-associated decreases in phosphatidate phosphohydrolase distribution onto the membranes were demonstrated under nearly all conditions. In liver homogenates taken from 1-day-old rats and incubated with 0.15 M KCl, most of the enzyme was active (associated with the membranes). Physiological salt concentration (0.15 M KCl) produced a 2-fold increase of oleate-induced translocation of phosphatidate phosphohydrolase activity in liver homogenates from 1-day-old rats; it had no effect on those from 60-day-old rats, and produced a notable decline in liver homogenates obtained from 180- and 360-day-old rats. The promoting effect of spermine on oleate-induced translocation of this enzyme activity was higher in younger rats when incubated in the absence of 0.15 M KCl. Chlorpromazine did not show its usual antagonizing effect on oleate-induced translocation of phosphatidate phosphohydrolase when added to homogenates taken from 1-day-old rats. The antagonizing effect was slightly apparent in liver homogenates from 30-day-old rats and was more pronounced in those from 60-day-old rats in which the values diminished to one-half and to one-third either in the presence or absence of 0.15 M KCl.  相似文献   

14.
The carbon dioxide and ethylene concentrations in tomato fruit ( Lycopersicon esculentum cv. Castelmart) and their stage of ripeness (characteristic external color changes) were periodically measured in fruit attached to and detached from the plant. An external collection apparatus was attached to the surface of individual tomato fruit to permit non-destructive sampling of internal gases. The concentration of carbon dioxide and ethylene in the collection apparatus reached 95% of the concentration in the fruit after 8 h. Gas samples were collected every 24 h. A characteristic climacteric surge in carbon dioxide (2-fold) and ethylene (10-fold) concentration occurred coincident with ripening of detached tomato fruit. Fruit attached to the plant exhibited a climacteric rise in ethylene (20-fold) concentration during ripening, but only a linear increase in carbon dioxide concentration. The carbon dioxide concentration increases in attached fruit during ripening, but the increase is a continuation of the linear increase seen in both attached and detached fruit before ripening and does not exhibit the characteristic pattern normally associated with ripening climacteric fruit. In tomato fruit, it appears that a respiratory climacteric per se, which has been considered intrinsic to the ripening of certain fruit, may not be necessary for the ripening of "climacteric" fruit at all, but instead may be an artifact of using harvested fruit.  相似文献   

15.
Smillie, R. M., Nott, R., Hetherington, S. E. and Öyustt, G. 1987. Chilling injury and recovery in detached and attached leaves measured by chlorophyll fluorescence Chilling injury was compared in detached and attached leaves chilled at 0 or 0.5°C by measuring the decrease in induced chlorophyll fluorescence in vivo. The fluorescence parameter measured was FR, the maximal rate of rise of induced chlorophyll fluorescence emission after irradiating dark-adapted leaves. The plants used were bean, Phaseolus vulgaris L. cv. Pioneer, and maize, Zea mays L. cvs hybrid GH 390 and Northern Belle. Leaves were detached and placed on wet paper and covered with thin polyethylene film to prevent water loss during chilling. Leaves left attached on plants were treated similarly. When chilled in this way at 100% relative humidity, the chilling-induced decrease in FR was the same in detached and attached leaves. For the attached leaves, the same result was obtained whether just a single leaf was chilled or the whole plant. Expression of chilling injury was greatest in fully turgid leaves and comparisons can be invalid unless the water status of the detached and attached leaves are the same. Problems arising from diurnal fluctuations in water potential of plants grown in a glasshouse were circumvented by placing leaves on the wet filter paper under polyethylene film prior to chilling, which allowed high water potentials to be regained, or mist sprays in the glasshouse were employed. Determinations of the time course for changes in FR of maize (cv. Northern Belle) during chilling at 0°C showed that FR decreased exponentially, at the same rate (time to 50% decrease in FR was 9.3 h) in detached and attached leaves. Chilling injury was largely reversible for the first 20 h of chilling stress as both detached and attached leaves recovered their pre-chilling values of FR after a further 20 h at 20°C in darkness. Leaves chilled for 48 h showed partial recovery, while those chilled for 72 h did not recover. Recovery was impeded by light. Inability to recover from chilling as indicated by measurements of FR was paralleled by the incidence of visible symptoms of injury. It is concluded that detached and attached leaves behave similarly during chilling and short-term recovery, provided a similarity in treatments is rigorously maintained.  相似文献   

16.
During the vase life of a rose flower, changes in the levels of abscisic acid (ABA) were observed: a decrease during the first 3 days, followed by a steady state at a low level, and finally a sharp increase in late senescence. Feeding [2-14C]ABA to isolated petals showed that metabolism was very active despite the age of the flower, oxidation processes increased with age, whereas conjugation decreased but the level of nonmetabolized ABA remained stable. When the isolated petal was subjected to water stress, whatever its age, the ABA level increased. Hydrolysis of ABA-GE was not involved in this phenomenon. Thus, ABA synthesis occurred in the isolated petal; it could be directly correlated to the decrease in water potential. However, the ABA increase in isolated petals was limited. Moreover, on the rose tree, increases in ABA levels were not correlated to water potential changes. ABA levels seemed, therefore, mainly regulated by changes in import from leaves and other parts of the flower.  相似文献   

17.
During the vase life of a rose flower, changes in the levels of abscisic acid (ABA) were observed: a decrease during the first 3 days, followed by a steady state at a low level, and finally a sharp increase in late senescence. Feeding [2-14C]ABA to isolated petals showed that metabolism was very active despite the age of the flower, oxidation processes increased with age, whereas conjugation decreased but the level of nonmetabolized ABA remained stable. When the isolated petal was subjected to water stress, whatever its age, the ABA level increased. Hydrolysis of ABA-GE was not involved in this phenomenon. Thus, ABA synthesis occurred in the isolated petal; it could be directly correlated to the decrease in water potential. However, the ABA increase in isolated petals was limited. Moreover, on the rose tree, increases in ABA levels were not correlated to water potential changes. ABA levels seemed, therefore, mainly regulated by changes in import from leaves and other parts of the flower.  相似文献   

18.
Tweedia caerulea flowers are sensitive to ethylene and the closing of the flowers, a characteristic of senescence, is accelerated by exposure to ethylene. T. caerulea flowers were continuously treated with ethanol at concentrations of 0, 2, 4, 6, 8, 10 or 12 %, and treatment levels at 4 % and above showed delayed closing. Ethanol accelerated climacteric increase in ethylene production from flowers. Although ethylene production was higher in gynoecium than in petals, ethanol treatment accelerated ethylene production by both organs. Exposure to ethylene increased autocatalytic ethylene production, and production was further accelerated by ethanol treatment. When flowers treated with ethanol were exposed to ethylene, senescence was delayed compared to that for untreated flowers, suggesting that ethanol reduces the sensitivity of flowers to ethylene. These results indicate that treatment with ethanol delays petal senescence in cut T. caerulea flowers, possibly through reduced sensitivity to ethylene.  相似文献   

19.
Silverthiosulphate which is a potent inhibitor of ethylene action was found to be ineffective in delaying senescence of detached flowers of Iris germanica whereas cycloheximide, a protein synthesis inhibitor, effectively delayed the senescence of these flowers and extended the longevity to 6 days. However, this treatment resulted in suppression of bud opening. When cycloheximide treatment was given at progressive intervals it became less effective in inhibiting bud opening and delaying senescence. Cycloheximide treatment maintained a higher protein content in the perianth tissue of flowers compared to untreated flowers.  相似文献   

20.
The effect of p -chloromercuribenzenesulfonic acid (PCMBS), carbonylcyanide- m -chlorophenylhydrazone (CCCP) and a high apoplastic pH (pH 7.5 compared with pH 5.5) on the release of sugars (sucrose and glucose) and amino acids from attached and detached seed coats of Pisum sativum L. cv. Marzia into a bathing solution was measured by means of the 'empty seed coat technique'. PCMBS reduced the release of sugars and amino acids from attached as well as from detached seed coats, suggesting that carrier-mediated transport might be involved. CCCP reduced sugar release from attached seed coats while amino acid release was hardly affected. In experiments with detached seed coats CCCP had no effect on release of either sugar or amino acids, suggesting that it is not energy-dependent. Raising the pH of the bathing solution from pH 5.5 to pH 7.5 slightly increased sugar release from both attached and detached seed coats while amino acid release was not affected. This might indicate a role of the apoplastic pH in regulating sugar release from the seed coat via a retrieval mechanism. The presented data indicate that there are important differences between sugars and amino acids with respect to transport processes in the seed coat. This is supported by the observation that the rate of amino acid release from the seed coat was higher than the rate of sugar release. The release data of detached seed coats were subjected to compartmental analysis in order to calculate rate constants for release from cell compartments. In the case of sugars, the half-times for emptying the cytoplasmic and vacuolar compartment were 0.8 h and 12.5 h. respectively. For amino acids the half-times were 0.5 h for emptying the cytoplasmic and 3.8 h for emptying the vacuolar compartment.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号