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1.
The regulatory role of ethylene in leaf senescence was studied with excised tobacco leaf discs which were allowed to senesce in darkness. Exogenous ethylene, applied during the first 24 hours of senescence, enhanced chlorophyll loss without accelerating the climacteric-like pattern of rise in both ethylene and CO 2, which occurred in the advanced stage of leaf senescence. Rates of both ethylene and CO 2 evolution increased in the ethylene-treated leaf discs, especially during the first 3 days of senescence. The rhizobitoxine analog, aminoethoxy vinyl glycine, markedly inhibited ethylene production and reduced respiration and chlorophyll loss. Pretreatment of leaf discs with Ag + or enrichment of the atmosphere with 5 to 10% CO 2 reduced chlorophyll loss, reduced rate of respiration, and delayed the climacteric-like rise in both ethylene and respiration. Ag + was much more effective than CO 2 in retarding leaf senescence. Despite their senescence-retarding effect, Ag + and CO 2, which are known to block ethylene action, stimulated ethylene production by the leaf discs during the first 3 days of the senescing period; Ag + was more effective than CO 2. The results suggest that although ethylene production decreases prior to the climacteric-like rise during the later stages of senescence, endogenous ethylene plays a considerable role throughout the senescence process, presumably by interacting with other hormones participating in leaf senescence. 相似文献
2.
High CO 2 concentration (0.5%) increased the rate of ethylene production, measured in a continuous flow system, in intact sunflower ( Helianthus annuus L.) plants. However, the rate of ethylene production subsided to near control levels after approximately 24 hours. The effect of high CO 2 could only be observed in light. Although high CO 2 concentration had no effect on the rate of ethylene production in darkness, prolonged exposure (approximately 16 hours) of plants to high CO 2 in the dark prevented the increase in ethylene production when the plants were exposed to light and high CO 2. 相似文献
3.
Ethylene production and respiration by Granny Smith apples were inhibited by treatment with 20% CO 2 for 2 hours. A similar effect was observed in tissue slices when treated at either 0 or 25°C. The inhibition continued even after an extended aeration period. There is also an inhibition of ethylene emission in tissue slices incubated with exogenous 1-aminocyclopropane-1-carboxylic acid (ACC). In general, CO2 treatment increased the ACC content of the tissue. These observations are consistent with the idea the action of CO2 is directed toward the enzyme system responsible for the conversion of ACC into ethylene. 相似文献
4.
The mechanism of light-inhibited ethylene production in excised rice ( Oryza sativa L.) and tobacco ( Nicotiana tabacum L.) leaves was examined. In segments of rice leaves light substantially inhibited the endogenous ethylene production, but when CO 2 was added into the incubation flask, the rate of endogenous ethylene production in the light increased markedly, to a level which was even higher than that produced in the dark. Carbon dioxide, however, had no appreciable effect of leaf segments incubated in the dark. The endogenous level of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, was not significantly affected by lightdark or CO 2 treatment, indicating that dark treatment or CO 2exerted its effect by promoting the conversion of ACC to ethylene. This conclusion was supported by the observations that the rate of conversion of exogenously applied ACC to ethylene was similarly inhibited by light, and this inhibition was relieved in the presence of CO 2. Similar results were obtained with tobacco leaf discs. The concentrations of CO 2 giving half-maximal activity was about 0.06%, which was only slightly above the ambient level of 0.03%. The modulation of ACC conversion to ethylene by CO 2 or light in detached leaves of both rice and tobacco was rapid and fully reversible, indicating that CO 2 regulates the activity, but not the synthesis, of the enzyme converting ACC to ethylene. Our results indicate that light inhibition of ethylene production in detached leaves is mediated through the internal level of CO 2, which directly modulates the activity of the enzyme converting ACC to ethylene.Abbreviation ACC
1-aminocyclopropane-1-carboxylic acid
Recipient of a Republic of China National Science Council Fellowship 相似文献
5.
The effect of light and CO 2 on both the endogenous and 1-aminocyclopropane-1-carboxylic acid (ACC)-dependent ethylene evolution from metabolically active detached leaves and leaf discs of Gomphrena globosa L. is reported. Treatment with varying concentrations of ACC did not appear to inhibit photosynthesis, respiration, or stomatal behavior. In all treatments, more ethylene was released into a closed flask from ACC-treated tissue, but the pattern of ethylene release with respect to light/dark/CO 2 treatments was the same. Leaf tissue in the light with a source of CO2 sufficient to maintain photosynthesis always generates 3 to 4 times more ethylene than tissue in the dark. Conversely, the lowest rate of ethylene release occurs when leaf tissue is illuminated and photosynthetic activity depletes the CO2 to the compensation point. Ethylene release in the dark is also stimulated by CO2 either added to the flask as bicarbonate or generated by dark respiration. Ethylene release increases dramatically and in parallel with photosynthesis at increasing light intensities in this C4 plant. Ethylene release appears dependent on CO2 both in the light and in the dark. Therefore, it is suggested that the important factor regulating the evolution of ethylene gas from leaves of Gomphrena may be CO2 metabolism rather than light per se. 相似文献
6.
The relationship of respiration and growth of seed, pericarp tissue and whole fruit of snap beans ( Phaseolus vulgaris L.) was studied. The whole fruit exhibited an apparent climacteric type of respiration pattern. This pattern resulted from an increase in CO 2 production by the enlarging seed followed by a rapid decrease in CO 2 evolution by the pericarp tissue, and the pattern was not associated with any concomitant increase in ethylene production. Therefore, the apparent climacteric respiration pattern of a developing bean fruit is not comparable to the phenomenon that occurs in other ripening fruits. 相似文献
7.
Both carbon dioxide and ethylene can affect the rate of root elongation. Carbon dioxide can also promote ethylene biosynthesis by enhancing the activity of 1-aminocylopropane-1-carboxylic acid (ACC) oxidase. Since the amount of CO 2 in the soil air, and in the atmosphere surrounding roots held in enclosed containers, is known to vary widely, we investigated the effects of varying CO 2 concentrations on ethylene production by excised and intact sunflower roots ( Helianthus annuus L. cv. Dahlgren 131). Seedlings were germinated in an aeroponic system in which the roots hung freely in a chamber and were misted with nutrient solution. This allowed for treatment, manipulation and harvest of undamaged and minimally disturbed roots. While exposure of excised roots to 0.5% CO 2 could produce a small increase in ethylene production (compared to roots in ambient CO 2), CO 2 concentrations of 2% and above always inhibited ethylene evolution. This inhibition of ethylene production by CO 2 was attributed to a reduction in the availability of ACC: however, elevated CO 2 had no effect on ACC oxidase activity. ACC levels in excised roots were depressed by CO 2 at a concentration of 2% (as compared to ambient CO 2), but n-malonyl-ACC (MACC) levels were not affected. Treating intact roots with 2% CO 2 inhibited elongation by over 50%. Maximum inhibition of elongation occurred 1 h after the CO 2 treatment began, but elongation rates returned to untreated values by 6 h. Supplying these same intact roots with 2% CO 2 did not alter ethylene evolution. Thus, in excised sunflower roots 2% CO 2 treatment reduces ethylene evolution by lowering the availability of ACC. Intact seedlings respond differently in that 2% CO 2 does not affect ethylene production in roots. These intact roots also temporarily exhibit a significantly reduced rate of elongation in response to 2% CO 2. 相似文献
8.
With glucose as a substrate, the oxygen consumption in yeast in inhibited by 2· 10 -5M ethylene diisothiocyanate. The degree of inhibition was only to a small extent dependant on pH. Radiorespirometric experiments with uniformely labelled glucose showed that the CO 2-production from glucose increased, probably due to increased glycolytic activity. Conversion of C-1 to CO 2 was unaffected by the inhibitor, while the evolution of CO 2 from C-6 was strongly inhibited. The same was the case with CO 2 from C-1 in acetate. Respiration of ethanol was more strongly inhibited than that of glucose or acetate. Experiments with dual wavelength spectrophotometry showed the inhibition to be located on the Krebs cycle side of the respiratory flavoproteins. It is concluded that the action of ethylene diisothiocyanate on respiration must be located at the mitochondria. 相似文献
9.
A method has been developed to measure concentrations of CO 2 in gases rapidly. A gas sample is injected into a flowing carrier gas that passes through an infrared CO 2 analyzer. A strip chart recorded peak response is obtained which is proportional to the CO 2 concentration. A resolution of better than 2 microliters of CO 2 per liter of gas was obtained. Seven to 10 seconds were required for sample analysis once the sample was obtained. Sorghum bicolor plant respiration was determined at different temperatures by measuring CO 2 using this system and by using a conventional system. The correlation between techniques was 0.996, and about the same variation occurred within each method. This technique greatly increased the efficiency of the infrared CO 2 analyzer in our laboratory for use in plant respiration and photosynthetic studies. 相似文献
10.
The effects of ethylene and CO 2 on shoot regeneration in excised leaf cultures of Paulownia kawakamii were examined. When both the gases were prevented from accumulating in the headspace of cultures using mercuric perchlorate and potassium hydroxide traps, shoot regeneration frequency improved and callus production was reduced compared to the control and cultures with only one of the gases trapped. Incorporation of either aminoethoxyvinylglycine (AVG) or 1-amino-cyclopropane-1-carboxylic acid (ACC) in the culture medium caused significant reduction in shoot regeneration. There was profuse callus production in the presence of high amounts of ACC, which was accompanied by over sixfold increase in the rate of ethylene production. However, in the presence of AVG callus production was delayed and shoot regeneration decreased, suggesting that low levels of ethylene might be needed for de novo shoot bud induction in Paulownia cultures.Abbreviations IAA
Indole-3-acetic acid
- MP
mercuric perchlorate
- AVG
aminoethoxyvinylglycine
- ACC
1-aminocyclopropane-1-carboxylic acid 相似文献
11.
森林和湿地是CO2、CH4和N2O等温室气体重要的源、汇和转换器,在全球气候变化过程中起着重要作用。森林和湿地温室气体通量受到诸多因子的作用,其中干扰便是一个重要的因素。不同干扰因素对于森林和湿地生态系统温室气体通量的影响,国际上已经开展了相应的研究。基于人为和自然两大类干扰方式,分别从采伐、施肥、垦殖等人为干扰因素和火烧、台风(飓风)等自然干扰因素综述了干扰对于森林和湿地生态系统CO2、CH4和N2O通量的影响。根据目前研究中存在的不足,提出了今后应需加强的领域,以期更好地揭示干扰对于森林和湿地生态系统温室气体通量的影响及作用机制,为今后深入开展相关研究提供一定的参考价值。 相似文献
12.
A comparison was made of energy metabolism of nodulated N 2 fixing plants and non-nodulated NO 3-fed plants of Lupinus albus L. Growth, N-increment, root respiration (O 2 uptake and CO 2 production) and the contribution of a SHAM-sensitive oxidative pathway (the alternative pathway) in root respiration were measured. Both growth rate and the rate of N-increment were the same in both series of plants. The rate of root respiration, both O 2 uptake and CO 2 production, and the activity of the SHAM-sensitive pathway were higher in NO 3-fed plants than in N 2 fixing plants. The rate of ATP production in oxidative phosphorylation was computed also to be higher in NO 3-fed plants. It is concluded that both carbohydrate costings and ATP costings for synthesis + maintenance of root material were lower in N 2 fixing than in NO 3-fed plants. The respiratory quotient of root respiration was 1.6 in N 2-fixing plants and 1.4 in NO 3-fed plants. These values were slightly higher than the values calculated on the basis of CO 2 output due to N-assimilation and the experimental values of O 2 uptake, but showed the same trend: highest in N 2 fixing plants. Root respiration of NO 3-fed plants showed a diurnal pattern (both O 2 uptake, CO 2 production and the activity of the SHAM-sensitive pathway), whilst no diurnal variation in root respiration was found in N 2 fixing plants. However, C 2H 2 reduction did show a diurnal rhythm, which is suggested to be related to the diurnal variation in transpiration. Addition of NO 3 to N 2 fixing plants increased the rate of root respiration and the activity of the alternative pathway. This treatment did not decrease C 2H 2 reduction and H 2 evolution within 4 days. Withdrawal of NO 3-supply from NO 3-fed plants decreased the rate of root respiration but had no effect on the relative activity of the alternative pathway. It is suggested that the higher rate of root respiration and the higher activity of the SHAM-sensitive pathway in NO 3-fed plants is due to a larger supply of carbohydrates to the roots, partly due to a better photosynthetic performance of the shoots and partly due to a higher capacity of the roots to attract carbohydrates. 相似文献
13.
The effect of Ca on senescence was followed in detached cucumber ( Cucumis sativus L.) cotyledons floating on various solutions in the dark. Compared with those in water, cotyledons in 10 −4 molar CaCl 2 exhibited reduced chlorophyll loss and H 2O 2 production, reduced and delayed ethylene production, and did not undergo a burst in CO 2 production. In contrast, Mg had little effect on cotyledon senescence, whereas K stimulated chlorophyll loss but did not increase H 2O 2 accumulation of ethylene and CO 2 production. This reduction in the rate of senescence by Ca could also be achieved by increasing the endogenous levels of Ca in the cotyledons before excision, although the reduction was less than that with Ca in the external solution. The addition of H 2O 2 to the solutions on which cotyledons were floated stimulated chlorophyll breakdown, but effects on ethylene and CO 2 were not consistent. 相似文献
14.
When treated with ethylene in O 2, conditioned potato ( Solanum tuberosum L. cv. Russet Burbank) tubers – that is, tubers kept at room temperature for 10 days or more – yield slices that are CN ? resistant. Ten % CO 2 in the gas mixture not only synergizes the effect of ethylene, but replaces the need for conditioning as well. The response to CO 2 is more pronounced with increasing time from harvest. By contrast fresh slices from untreated tubers are CN ? sensitive, as are slices from tubers incubated in O 2 or O 2 plus CO 2. The suggestion is made that CN ? resistance is constitutive, and that treatment with ethylene/CO 2 in O 2 confers on potato tuber tissue a resistance to the extensive degradation of membrane phospholipids that normally attends slicing and leads to the loss of CN ? resistance. In this connection respiration inhibition by imidazole, an inhibitor of fatty acid α-oxidation, is extensive in slices of untreated tubers, and sharply diminished in slices of ethylene-treated tubers in proportion to their CN ? resistance. The coextensive rise of respiration rate and CN ? resistance in aged potato slices has led to the presumption that the CN ?-resistant path mediates the respiration climax. Accordingly the alkaloid, lycorine, has been considered to inhibit the development of CN ? resistance in aging potato slices because it curtails the wound-induced respiration. A comparison was carried out on the effect of lycorine on CN ?-sensitive and CN ?-resistant fresh slices – the latter obtained from ethylene/CO 2-treated tubers. Lycorine suppressed the development of the wound-induced respiration without restricting the development of CN ? resistance. 相似文献
15.
Tomato fruit ( Lycopersicon esculentum Mill. var. V. R. Moscow) harvested at the mature green stage were ripened by treatments with ethylene, oxygen, and oxygen plus ethylene. Treatments were made under dark and light conditions. Ethylene increased the ripening and respiration rates of the tomatoes. The fruit treated with ethylene had a general increase in beta carotene and lycopene when compared with untreated controls. The per cent acid was variable from year to year in the fruit treated with ethylene. The fruit ripened in ethylene had higher concentrations of citric acid than did the untreated controls. Treatments with oxygen decreased the reducing sugars and at the high concentrations used, had no effect on the rate of lycopene synthesis. Light treatments increased the per cent acid, reducing sugars, and color of the ripened fruit. The increase in color was related to an increase in both beta carotene and lycopene. Light treatment seemed to decrease the respiration rate of the fruit not treated with ethylene. Studies usingC 14O 2 showed that this may be due to utilization of CO 2 evolved from respiration by the green fruit in photosynthesis. 相似文献
16.
Significant increases in root density, crop growth and productivity have been observed following soil additions of biochar, which is a solid product from the pyrolysis of biomass. In addition, alterations in the soil microbial dynamics have been observed following biochar amendments, with decreased carbon dioxide (CO 2) respiration, suppression of methane (CH 4) oxidation and reduction of nitrous oxide (N 2O) production. However, there has not been a full elucidation of the mechanisms behind these effects. Here we show data on ethylene production that was observed from biochar and biochar-amended soil. Ethylene is an important plant hormone as well as an inhibitor for soil microbial processes. Our current hypothesis is that the ethylene is biochar derived, with a majority of biochars exhibiting ethylene production even without soil or microbial inoculums. There was increased ethylene production from non-sterile compared to sterile soil (215%), indicating a role of soil microbes in the observed ethylene production. Production varied with different biomass sources and production conditions. These observations provide a tantalizing insight into a potential mechanism behind the biochar effects observed, particularly in light of the important role ethylene plays in plant and microbial processes. 相似文献
17.
Although desert ecosystems are predicted to be the most responsive to elevated CO 2, low nutrient availability may limit increases in productivity and cause plants in deserts to allocate more resources to root biomass or activity for increased nutrient acquisition. We measured root respiration of two Mojave Desert shrubs, Ambrosia dumosa and Larrea tridentata, grown under ambient (~375 ppm) and elevated (~517 ppm) CO 2 concentrations at the Nevada Desert FACE Facility (NDFF) over five growing seasons. In addition, we grew L. tridentata seedlings in a greenhouse with similar CO 2 treatments to determine responses of primary and lateral roots to an increase in CO 2. In both field and greenhouse studies, root respiration was not significantly affected by elevated CO 2. However, respiration of A. dumosa roots <1 month old was significantly greater than respiration of A. dumosa roots between 1 and 4 months old. For both shrub species, respiration rates of very fine (<1.0 mm diameter) roots were significantly greater than those of fine (1–2 mm diameter) roots, and root respiration decreased as soil water decreased. Because specific root length was not significantly affected by CO 2 and because field minirhizotron measurements of root production were not significantly different, we infer that root growth at the NDFF has not increased with elevated CO 2. Furthermore, other studies at the NDFF have shown increased nutrient availability under elevated CO 2, which reduces the need for roots to increase scavenging for nutrients. Thus, we conclude that A. dumosa and L. tridentata root systems have not increased in size or activity, and increased shoot production observed under elevated CO 2 for these species does not appear to be constrained by the plant's root growth or activity. 相似文献
18.
The effect of gibberellin A 1 (GA 1) on production of ethylene by cowpea ( Vigna sinensis cv Blackeye pea no. 5) epicotyl explants and its relationship to epicotyl elongation was investigated. The explants were placed upright in water and incubated in sealed culture tubes or in large jars. GA, and IAA in ethanol solution were injected into the subapical tissues of the decapitated epicotyls. Cowpea epicotyl explants elongated after GA but not after IAA treatment, and they were very sensitive to exogenous ethylene. As little as 0.14 1/1 ethylene reduced significantly GA 1-induced epicotyl elongation.Treatment with GA 1 induced the production of ethylene which began 10 h after GA application, showed a peak at about 22 h and then declined. The yield of ethylene was proportional to the amount of GA, injected. The inhibition of epicotyl elongation in closed tubes was avoided by absorbing ethylene released with Hg(Cl0 4) 2 , or by adding AVG to the incubation solution to inhibit ethylene production. Treatment with IAA elicited a rapid production of ethylene which ceased about 10 h after application. The effects of IAA and GA 1 on ethylene production were additive.Abbreviations AVG
aminoethoxyvinylglycine 2-amino-4-(2-aminoethoxy)- trans-3butenoic acid
- ACC
1-aminocyclopropane-1-carboxylic acid
- GA
gibberellin
- IAA
indole-3-acetic acid 相似文献
19.
Ethylene production by primary roots of 72–h-old intact seedlings of Zea mays L. cv. LG11 was studied under ambient and sub-ambient oxygen partial pressures (pO 2) using a gas flow-through system linked to a photoacoustic laser detector. Despite precautions to minimize physical perturbation to seedlings while setting-up, ethylene production in air was faster during the first 6h than later, in association with a small temporary swelling of the roots. When roots were switched from air (20–8kPa O 2) to 3 or 5kPa O 2 after 6h, ethylene production increased within 2—3 h. When, the roots were returned to air 16 h later, ethylene production decreased within 2—3 h. The presence of 10kPa CO 2 did not interfere with the effect of 3kPa O 2. Transferring roots from air to 12–5kPa did not change ethylene production, while a reduction to 1 kPa O 2 induced a small increase. The extra ethylene formed in 3 and 5 kPa O 2 was associated with plagiotropism, swelling, root hair production, and after 72 h, increased amounts of intercellular space (aerenchyma) in the root cortex. Root extension was also slowed down, but the pattern of response to oxygen shortage did not always match that of ethylene production. On return to air, subsequent growth patterns became normal within a few hours. In the complete absence of oxygen, no ethylene production was detected, even when anaerobic roots were returned to air after 16 h. 相似文献
20.
The effect of elevated CO 2 on growth of wheat plants ( Triticum aestivum cv. Minaret) and soil protozoan and bacterial populations was investigated in soil pots placed in open top chambers fumigated with ambient air or air enriched with CO 2 (ambient + 320 l L –1 CO 2). We harvested plants two times during the growing season and measured the biomass and the C and N content of roots and shoots. The soil was divided into bulk and rhizosphere soil and the number of bacteria (colony-forming units, CFU) and protozoa was determined. There was no effect of atmospheric CO 2 content on the number of bacteria, but the total number of bacterivorous protozoa was higher in pots from the elevated CO 2 treatment. This increase was mainly due to an increase in the number of protozoa in the bulk soil. Density of protozoa in the rhizosphere was not affected by elevated CO 2. This suggests that the increase in protozoan numbers was a result of a general increase in rhizodeposition, presumably caused by increased root production, and not to an increased root exudation per root mass. After harvest, soil from the two treatments was incubated with and without roots and the respiration rate was estimated at intervals for 200 days. During the first 55 days, the specific root induced respiration rate was not affected by the CO 2 level at which the plants had been grown, indicating that the quality of the easily decomposable components of the roots was not affected by CO 2 level. 相似文献
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