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1.
The respiration of potato tubers ( Solanum tuberosum var. Russet Burbank) which have been kept at room temperature for 10 days is stimulated upon subsequent treatment with C 2H 4 (10 microliters per liter) and O 2. The respiratory rise reaches a peak in 24 to 30 hours and thereafter declines. Coincident with the rise in tuber respiration is an increase in the respiratory rates of fresh slices and isolated mitochondria. Slices and mitochondria from C 2H 4- and O 2-treated tubers also display substantial resistance to CN, and the resistant respiration is inhibited by hydroxamates. The longer the tubers are stored after harvest, the less effective is C2H4 in causing CN resistance in slices and mitochondria from treated tubers. Addition of 10% CO2 to the C2H4-O2 mixture, however, causes extensive CN resistance to develop, even in slices and mitochondria from old tubers. The results show that C2H4, O2, and CO2 act synergistically to induce alternative path development in potatoes. 相似文献
2.
Lung damage during hyperoxia has been postulated to be due to increased rates of local organ oxygen radical production. Lung homogenate respiration was inhibited with cyanide, and residual respiration was used as an indicator of electron diversion to O 2? and H 2O 2. Cyanide-resistant respiration in lung homogenates, supplemented with 1 mm NADH, increased linearly with oxygen tension, and accounted for 7% of total respiration in air and for 17% of total respiration when homogenates were incubated in 80% oxygen. Exposure of rats to 85% oxygen for 7 days induces tolerance to the lethal effects of 100% oxygen. Rats which previously breathed 85% oxygen for 7 days had a greater CN ?-resistant respiration than control rats. This implies that adaptation to hyperoxia does not include decreased lung tissue oxygen radical production as indicated by CN ?-resistant respiration. One possible explanation for the increased CN ?-resistant respiration in oxygen tolerant rat lungs is that they contain increased cell mass. Lung homogenates of rats exposed to 85% oxygen for 7 days also had 2.5 times greater thiobarbituric acid positive material than controls, indicating that increased lung lipid peroxidation occurs as a consequence of hyperoxia. Incubation of normal rat lung homogenates under hyperoxic conditions also acutely increased lipid peroxidation, which could be inhibited by both superoxide dismutase and catalase. This confirms that hyperoxia enhances cellular production of O 2? and H 2O 2 and implies an essential role for both O 2? and H 2O 2 in hyperoxic lung damage. 相似文献
3.
Treating intact white potato ( Solanum tuberosum L.) tuber with ethylene in air or O 2 made it possible to obtain freshly cut slices which exhibit cyanide-resistant respiration. The cyanide-resistant path requires induction in whole tubers. The data also indicate that high O 2 concentration is necessary for the full development of cyanide-resistant respiration. 相似文献
4.
Applying high concentrations of CO 2 to whole potato tubers stimulated a rapid and pronounced respiratory gas exchange, which persisted for a prolonged time. The upsurge in respiration was proportional to the applied CO 2 concentrations and was further augmented by high O 2 levels. Tests using whole potatoes, or potato tissue slices from tubers previously treated with CO 2, indicated that the rapid CO 2-induced respiration is sensitive to cyanide during the first 24 hours of CO 2 application. The respiratory rise cannot be attributed to the emergence of a cyanide-resistant alternative electron transport pathway, although prolonged applications of CO 2, up to 72 hours, led to a gradual development of the pathway. CO 2-stimulated respiration was accompanied by a pronounced decline in the content of starch and glucose 6-phosphate, suggesting an active utilization of respiratory substrates. The ATP content in the CO 2-treated potatoes increased markedly, resembling similar increases in tissues undergoing respiratory upsurge. 相似文献
5.
The interdependence of the development of wound-induced respiration and membrane-related phospholipid biosynthesis in potato tuber ( Solanum tuberosum var. Russet) slices was established by the use of agents which selectively affect lipid and phospholipid synthesis. Cerulenin, a specific inhibitor of de novo fatty acid synthesis, inhibited the ultimate development of wound-induced respiration and of cyanide resistance only when given in the critical first 10 to 12 hours of slice aging. Similarly, when slices were exposed to the choline analogue dimethylaminoethanol within the first 10 hours, the phospholipid composition of the membrane lipids was drastically altered, the wound-induced respiration in a 24-hr period was substantially curtailed, and the development of cyanide insensitivity was sharply inhibited. These observations indicate that time-restricted membrane-related phospholipid synthesis is prerequisite to the development of wound-induced respiration and concurrent cyanide insensitivity. 相似文献
6.
A continuous application of ethylene (10 μl/l) and propylene (500 μl/l) to potato tubers ( Solanum tuberosum L.) resulted in an upsurge of respiration and a concomitant rise in peroxides. When applied in 100% O 2, the effect of ethylene and propylene on respiration and peroxide formation was augmented. Hydrogen cyanide (500 μl/l) mimicked the action of ethylene and propylene inducing a respiratory rise and a corresponding increase in peroxides. As with ethylene, the effect of HCN was augmented in high O 2 tensions. The results support the suggestion that ethylene activates the cyanide-insensitive respiratory pathway. 相似文献
7.
Ethylene, cyanide gas, and volatalized ethanol, acetaldehyde, and acetic acid were applied in a continuous flow to whole potato tubers. Freshly cut slices were obtained periodically during the treatment, and showed a progressive development of a cyanide-resistant respiration. The application of the employed volatiles in 100% O 2 accelerated the onset and the magnitude of the cyanide-resistant respiration. 相似文献
8.
The respiration of fresh potato ( Solanum tuberosum, var. Russet Burbank) slices is predominantly cyanide-sensitive whether in the presence or absence of uncoupler. By contrast, the wound-induced respiration which develops in thin slices with aging is cyanide-resistant, and in the presence of cyanide, sensitive to chlorobenzhydroxamic acid, a selective inhibitor of the cyanide-resistant respiration. Titration of the alternate path in coupled slices with chlorobenzhydroxamic acid, in the presence and absence of cyanide, shows that the contribution of the cyanide-resistant pathway to the wound-induced respiration is zero. Similar titrations with uncoupled slices reveal that the alternate path is engaged and utilized extensively. The maximal capacity of the cytochrome path (Vcyt) has been estimated in fresh and aged slices in the presence of the uncoupler carbonyl-cyanide m-chlorophenyl hydrazone. It has been found that Vcyt of aged slices is but 30 to 40% higher than that of fresh slices. The results suggest that the bulk of the wound-induced respiration is mediated through the cytochrome pathway which exists in fresh slices in suppressed form, and which is fully expressed by slice aging. The engagement of the alternate path by uncouplers in aged slices is attributed to an increase in substrate mobilization, with the result that the electron transport capacity of the cytochrome chain is exceeded. 相似文献
9.
Soil microbial biomass C (C mic) is a sensitive indicator of trends in organic matter dynamics in terrestrial ecosystems. This study was conducted to determine the effects of tropospheric CO 2 or O 3 enrichments and moisture variations on total soil organic C (C org), mineralizable C fraction (C Min), C mic, maintenance respiratory (qCO 2) or C mic death (qD) quotients, and their relationship with basal respiration (BR) rates and field respiration (FR) fluxes in wheat‐soybean agroecosystems. Wheat ( Triticum aestivum L.) and soybean ( Glycine max. L. Merr) plants were grown to maturity in 3‐m dia open‐top field chambers and exposed to charcoal‐filtered (CF) air at 350 μL CO 2 L ?1; CF air + 150 μL CO 2 L ?1; nonfiltered (NF) air + 35 nL O 3 L ?1; and NF air + 35 nL O 3 L ?1 + 150 μL CO 2 L ?1 at optimum (? 0.05 MPa) and restricted soil moisture (? 1.0 ± 0.05 MPa) regimes. The + 150 μL CO 2 L ?1 additions were 18 h d ?1 and the + 35 nL O 3 L ?1 treatments were 7 h d ?1 from April until late October. While C org did not vary consistently, C Min, C mic and C mic fractions increased in soils under tropospheric CO 2 enrichment (500 μL CO 2 L ?1) and decreased under high O 3 exposures (55 ± 6 nL O 3 L ?1 for wheat; 60 ± 5 nL O 3 L ?1 for soybean) compared to the CF treatments (25 ± 5 nL O 3 L ?1). The qCO 2 or qD quotients of C mic were also significantly decreased in soils under high CO 2 but increased under high O 3 exposures compared to the CF control. The BR rates did not vary consistently but they were higher in well‐watered soils. The FR fluxes were lower under high O 3 exposures compared to soils under the CF control. An increase in C mic or C mic fractions and decrease in qCO 2 or qD observed under high CO 2 treatment suggest that these soils were acting as C sinks whereas, reductions in C mic or C mic fractions and increase in qCO 2 or qD in soils under elevated tropospheric O 3 exposures suggest the soils were serving as a source of CO 2. 相似文献
10.
The effect of Ca 2+ on programmed death of guard cells (GC) and epidermal cells (EC) determined from destruction of the cell nucleus was investigated in epidermis of pea leaves. Ca 2+ at concentrations of 1–100 μM increased and at a concentration of 1 mM prevented the CN—induced destruction of the nucleus in GC, disrupting the permeability barrier of GC plasma membrane for propidium iodide (PI). Ca 2+ at concentrations of 0.1–1 mM enhanced drastically the number of EC nuclei stained by PI in epidermis treated with chitosan, an inducer of programmed cell death. The internucleosomal DNA fragmentation caused by CN ? was suppressed by 2 mM Ca 2+ on 6 h incubation, but fragmentation was stimulated on more prolonged treatment (16 h). Presumably, the disruption of the permeability barrier of plasma membrane for PI is not a sign of necrosis in plant cells. Quinacrine and diphenylene iodonium at 50 μM concentration prevented GC death induced by CN ? or CN ? + 0.1 mM Ca 2+ but had no influence on respiration and photosynthetic O 2 evolution in pea leaf slices. The generation of reactive oxygen species determined from 2′,7′-dichlorofluorescein fluorescence was promoted by Ca 2+ in epidermal peels from pea leaves. 相似文献
11.
Treatment of intact potato ( Solanum tuberosum L.) tubers with acetaldehyde, ethanol or acetic-acid vapors led to a respiratory upsurge which was further increased when the volatiles were applied in 100% O 2. Mitochondria from tubers held in 100% O 2 (O 2 control) displayed a substrate state, state 3, and state 4 in respiration, whereas in mitochondria from the volatile-treated tubers the respiratory rate of the different states was virtually indistinguishable. This respiratory pattern was companied by the development of a cyanide-resistant respiration since these mitochondria exhibited resistance to CN and sensitivity to CN+salicylhydroxamic acid. Acetaldehyde-treated potatoes showed a time-course development (up to 36 h) of cyanide resistance and concomitant sensitivity to salicylhydroxamic acid, indicating the onset of synthetic processes leading to the observed changes in mitochondrial respiration.Abbreviations V
total respiration rate
- V cyt
velocity of O 2 uptake attributable to cytochrome oxidase
- V alt
velocity of O 2 uptake attributable to the alternate oxidase
- RCR
respiratory control ratio
- SHAM
salicylhydroxamic acid
Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers University, New Brunswick, N.J., USA 相似文献
12.
During soil waterlogging, plants experience O 2 deficits, elevated ethylene, and high CO 2 in the root‐zone. The effects on chickpea ( Cicer arietinum L.) and faba bean ( Vicia faba L.) of ethylene (2 μL L ?1), CO 2 (2–20% v/v) or deoxygenated stagnant solution were evaluated. Ethylene and high CO 2 reduced root growth of both species, but O 2 deficiency had the most damaging effect and especially so for chickpea. Chickpea suffered root tip death when in deoxygenated stagnant solution. High CO 2 inhibited root respiration and reduced growth, whereas sugars accumulated in root tips, of both species. Gas‐filled porosity of the basal portion of the primary root of faba bean (23%, v/v) was greater than for chickpea (10%), and internal O 2 movement was more prominent in faba bean when in an O 2‐free medium. Ethylene treatment increased the porosity of roots. The damaging effects of low O 2, such as death of root tips, resulted in poor recovery of root growth upon reaeration. In conclusion, ethylene and high CO 2 partially inhibited root extension in both species, but low O 2 in deoxygenated stagnant solution had the most damaging effect, even causing death of root tips in chickpea, which was more sensitive to the low O 2 condition than faba bean. 相似文献
13.
Mitochondria from whole potatoes ( Solanum tuberosum) ordinarily fail to oxidize respiratory substrates and to consume molecular O 2 in the presence of cyanide. Mitochondrial preparations obtained from tubers previously held for 24 hours in ethylene (10 microliters per liter) in air are only partially inhibited by cyanide. Application of ethylene in 100% O 2 led to an additional increase in the resistance of the mitochondrial respiration to cyanide. The resistance to cyanide was accompanied by a decrease in the respiratory control but no change in oxidative phosphorylation as shown by the measurement of ATP synthesis. 相似文献
14.
Kinetics of inhibition of cyanide-insensitive O 2 uptake by n-propyl gallate (PG) and salicylhydroxamic acid (SHAM) were determined in fresh slices from ethylene-treated tubers of Solanum tuberosum `Norchip' and with mitochondria and lipoxygenase (EC 1.13.11.12) isolated from these tubers. PG and SHAM appeared to be inhibiting at identical sites in mitochondria but at disparate sites in slices. The apparent KI for SHAM was similar in mitochondria and slices. However, the apparent KI for PG in mitochondria was about 40-fold lower than the KI for PG inhibition of lipoxygenase activity. The amount of lipoxygenase associated with mitochondria increased when tubers were treated with ethylene. PG, but not SHAM, inhibited aging-induced development of cyanide-insensitive respiration. The latter two phenomena are in accord with the hypothesis that lipid metabolism is required for the development of the alternative pathway. 相似文献
15.
Plants were obtained with novel O 2-resistant photosynthetic characteristics. At low CO 2 (250-350 μL CO 2 L −1) and 30°C when O 2 was increased from 1% to 21% to 42%, the ratio of net CO 2 uptake in O 2-resistant whole plants or leaf discs compared to wild type increased progressively, and this was not related to stomatal opening. Dihaploid plantlets regenerated from anther culture were initially screened and selected for O 2-resistant growth in 42% O 2/160 μL CO 2 L −1 and 0.18% of the plantlets showed O 2-resistant photosynthesis. About 30% of the progeny (6 of 19 plants) of the first selfing of a fertile plant derived from a resistant dihaploid plant had O 2-resistant photosynthesis, and after a second selfing this increased to 50% (6 of 12 plants). In 21% O 2 and low CO 2, net photosynthesis of the resistant plants was about 15% greater on a leaf area basis than wild type. Net photosynthesis was compared in leaf discs at 30 and 38°C in 21% O 2, and at the higher temperature O 2-resistant plants showed still greater photosynthesis than wild type. The results suggest that the O 2-resistant photosynthesis described here is associated with a decreased stoichiometry of CO 2 release under conditions of rapid photorespiration. This view was supported by the finding that leaves of O 2-resistant plants averaged 40% greater catalase activity than wild type. 相似文献
16.
Measurements of net fluxes of CO 2 and O 2 from leaves and chlorophyll a fluorescence were used to determine the role of mitochondrial respiration during nitrate (NO 3–) assimilation in both a C 3 (wheat) and a C 4 (maize) plant. Changes in the assimilatory quotient (net CO 2 consumed over net O 2 evolved) when the nitrogen source was shifted from NO 3– to NH 4+ (Δ AQ) provided a measure of shoot NO 3– assimilation. According to this measure, elevated CO 2 inhibited NO 3– assimilation in wheat but not maize. Net O 2 exchange under ambient CO 2 concentrations increased in wheat plants receiving NO 3– instead of NH 4+, but gross O 2 evolution from the photosynthetic apparatus ( JO2) was insensitive to nitrogen source. Therefore, O 2 consumption within wheat photosynthetic tissue (ΔΟ 2), the difference between JO2 and net O 2 exchange, decreased during NO 3– assimilation. In maize, NO 3– assimilation was insensitive to changes in intercellular CO 2 concentration ( Ci); nonetheless, ΔΟ 2 at low Ci values was significantly higher in NO 3–‐fed than in NH 4+‐fed plants. Changes in O 2 consumption during NO 3– assimilation may involve one or more of the following processes: ( a) Mehler ascorbate peroxidase (MAP) reactions; ( b) photorespiration; or ( c) mitochondrial respiration. The data presented here indicates that in wheat, the last process, mitochondrial respiration, is decreased during NO 3– assimilation. In maize, NO 3– assimilation appears to stimulate mitochondrial respiration when photosynthetic rates are limiting. 相似文献
17.
CO 2 exchange rates per unit dry weight, measured in the field on attached fruits of the late-maturing Cal Red peach cultivar, at 1200 μmol photons m ?2S ?1 and in dark, and photosynthetic rates, calculated by the difference between the rates of CO 2 evolution in light and dark, declined over the growing season. Calculated photosynthetic rates per fruit increased over the season with increasing fruit dry matter, but declined in maturing fruits apparently coinciding with the loss of chlorophyll. Slight net fruit photosynthetic rates ranging from 0. 087 ± 0. 06 to 0. 003 ± 0. 05 nmol CO 2 (g dry weight) ?1 S ?1 were measured in midseason under optimal temperature (15 and 20°C) and light (1200 μmol photons m ?2 S ?1) conditions. Calculated fruit photosynthetic rates per unit dry weight increased with increasing temperatures and photon flux densities during fruit development. Dark respiration rates per unit dry weight doubled within a temperature interval of 10°C; the mean seasonal O 10 value was 2. 03 between 20 and 30°C. The highest photosynthetic rates were measured at 35°C throughout the growing season. Since dark respiration rates increased at high temperatures to a greater extent than CO 2 exchange rates in light, fruit photosynthesis was apparently stimulated by high internal CO 2 concentrations via CO 2 refixation. At 15°C, fruit photosynthetic rates tended to be saturated at about 600 μmol photons m ?2 S ?1. Young peach fruits responded to increasing ambient CO 2 concentrations with decreasing net CO 2 exchange rates in light, but more mature fruits did not respond to increases in ambient CO 2. Fruit CO 2 exchange rates in the dark remained fairly constant, apparently uninfluenced by ambient CO 2 concentrations during the entire growing season. Calculated fruit photosynthetic rates clearly revealed the difference in CO 2 response of young and mature peach fruits. Photosynthetic rates of younger peach fruits apparently approached saturation at 370 μl CO 21 ?2. In CO 2 free air, fruit photosynthesis was dependent on CO 2 refixation since CO 2 uptake by the fruits from the external atmosphere was not possible. The difference in photosynthetic rates between fruits in CO 2-free air and 370 μl CO 2 1 ?1 indicated that young peach fruits were apparently able to take up CO 2 from the external atmosphere. CO 2 uptake by peach fruits contributed between 28 and 16% to the fruit photosynthetic rate early in the season, whereas photosynthesis in maturing fruits was supplied entirely by CO 2 refixation. 相似文献
18.
Meta‐analysis techniques were used to examine the effect of elevated atmospheric carbon dioxide [CO 2] on the protein concentrations of major food crops, incorporating 228 experimental observations on barley, rice, wheat, soybean and potato. Each crop had lower protein concentrations when grown at elevated (540–958 μmol mol ?1) compared with ambient (315–400 μmol mol ?1) CO 2. For wheat, barley and rice, the reduction in grain protein concentration was ~10–15% of the value at ambient CO 2. For potato, the reduction in tuber protein concentration was 14%. For soybean, there was a much smaller, although statistically significant reduction of protein concentration of 1.4%. The magnitude of the CO 2 effect on wheat grains was smaller under high soil N conditions than under low soil N. Protein concentrations in potato tubers were reduced more for plants grown at high than at low concentrations of ozone. For soybean, the ozone effect was the reverse, as elevated CO 2 increased the protein concentration of soybean grown at high ozone concentrations. The magnitude of the CO 2 effect also varied depending on experimental methodology. For both wheat and soybean, studies performed in open‐top chambers produced a larger CO 2 effect than those performed using other types of experimental facilities. There was also indication of a possible pot artifact as, for both wheat and soybean, studies performed in open‐top chambers showed a significantly greater CO 2 effect when plants were rooted in pots rather than in the ground. Studies on wheat also showed a greater CO 2 effect when protein concentration was measured in whole grains rather than flour. While the magnitude of the effect of elevated CO 2 varied depending on the experimental procedures, a reduction in protein concentration was consistently found for most crops. These findings suggest that the increasing CO 2 concentrations of the 21st century are likely to decrease the protein concentration of many human plant foods. 相似文献
19.
Cyanide-resistant O(2) consumption can be stimulated by either treating whole white potato tubers (Norchip) with ethylene, in the presence of 100% O(2), or aging slices obtained from untreated potato tubers. A comparison of alternative pathway activity elicited by either treatment was undertaken. The proportion of electrons flowing through the alternative path in the presence of intermediate concentrations of KCN and at various concentrations of salicylhydroxamic acid was identical in both cases. However, the respiration of slices from ethylene-treated tubers was in every case stimulated by KCN, whereas the aged slices never exhibited this phenomenon. Furthermore, the metabolism of d-[U-(14)C]glucose was several hundred times greater in aged slices than in fresh slices from C(2)H(4)-treated tubers. These results, along with the respiratory kinetics of aged slices from ethylene-treated tubers, suggest that aged slices and fresh slices from ethylene-treated tubers are biochemically dissimilar. 相似文献
20.
Increases in atmospheric CO 2 and tropospheric O 3 may affect forest N cycling by altering plant litter production and the availability of substrates for microbial metabolism. Three years following the establishment of our free‐air CO 2–O 3 enrichment experiment, plant growth has been stimulated by elevated CO 2 resulting in greater substrate input to soil; elevated O 3 has counteracted this effect. We hypothesized that rates of soil N cycling would be enhanced by greater plant productivity under elevated CO 2, and that CO 2 effects would be dampened by O 3. We found that elevated CO 2 did not alter gross N transformation rates. Elevated O 3 significantly reduced gross N mineralization and microbial biomass N, and effects were consistent among species. We also observed significant interactions between CO 2 and O 3: (i) gross N mineralization was greater under elevated CO 2 (1.0 mg N kg ?1 day ?1) than in the presence of both CO 2 and O 3 (0.5 mg N kg ?1 day ?1) and (ii) gross NH 4+ immobilization was also greater under elevated CO 2 (0.8 mg N kg ?1 day ?1) than under CO 2 plus O 3 (0.4 mg N kg ?1 day ?1). We used a laboratory 15N tracer method to quantify transfer of inorganic N to organic pools. Elevated CO 2 led to greater recovery of NH 4+‐ 15N in microbial biomass and corresponding lower recovery in the extractable NO 3? pool. Elevated CO 2 resulted in a substantial increase in NO 3?‐ 15N recovery in soil organic matter. We observed no O 3 main effect and no CO 2 by O 3 interaction effect on 15N recovery in any soil pool. All of the above responses were most pronounced beneath Betula papyrifera and Populus tremuloides, which have grown more rapidly than Acer saccharum. Although elevated CO 2 has increased plant productivity, the resulting increase in plant litter production has yet to overcome the influence of the pre‐existing pool of soil organic matter on soil microbial activity and rates of N cycling. Ozone reduces plant litter inputs and also appears to affect the composition of plant litter in a way that reduces microbial biomass and activity. 相似文献
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