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1.
The respiration rate of leaves and mesophyll protoplasts of pea (Pisum sativum L.), from plants which were previously kept in darkness for 24 h was doubled following a period of photosynthesis at ambient
level of O2 (21 %), whereas the low level of O2 (1 % and 4 % for leaves and protoplasts, respectively) reduced this light-enhanced dark respiration (LEDR) to the rate as
noted before the illumination. Similarly to respiration rate, the oxygen at used concentrations had no effect on the ATP/ADP
ratio in the dark-treated leaves. However, the ATP/ADP ratio in leaves photosynthesizing at 21 % O2 was higher (up to 40 %, dependence on CO2 concentration in the range 40–1600 1 dm−3) than in those photosynthesizing at 1 % O2 or darkened at air (21 % O2). Also, at 1 % O2 the accumulation of malate was suppressed (by about 40 %), to a value noted for leaves darkened at 21 % O2. The dark-treatment of leaves reduced the ability of isolated mitochondria to oxidize glycine (by about twofold) and succinate,
but not malate. Mitochondria from both the light- and dark-treated leaves did not differ in qualitative composition of free
amino acids, however, there were significant quantitative differences especially with respect to aspartate, alanine, glutamate
and major intermediates of the photorespiratory pathway (glycine, serine). Our results suggest that accumulation of photorespiratory
and respiratory metabolites in pea leaves during photosynthesis at 1 % O2 is reduced, hence the suppression of postillumination respiration rate. 相似文献
2.
Postillumination CO2 fixation by wheat leaves was studied following light-limited photosynthetic conditions. Dark CO2 fixation showed two phases differing by their rates of CO2 uptake and carbon metabolism. These two phases are related to preillumination light flux density. During the first 30s of darkness, assimilated CO2 was found in PGA, alanine, malate and aspartate. After 5 min of darkness, it was additionally found in phosphorylated sugars.The lack of labelling of glycolate pathway intermediates shows that the Calvin cycle cannot run in the dark.The synthesized compounds indicate that reducing power but not ATP is available after turning the light off. This observation suggests that during pre-illumination, when light strictly limits photosynthesis, ATP supply would be the first limiting factor.
Résumé La fixation post-illuminatoire de CO2 par des feuilles de blé est étudiée, après une période de photosynthèse en lumière limitante.Les cinétiques de la vitesse de fixation du CO2 après extinction présentent deux phases, se différenciant par la vitesse de fixation du CO2 et par les voies métaboliques suivies par le carbone.Pendant les premières 30s d'obscurité, le CO2 fixé est retrouvé principalement dans le PGA, l'alanine, le malate et l'aspartate. Après 5 min d'obscurité le carbone est retrouvé également dans les esters phosphorylés des oses.L'absence de radioactivité dans les intermédiaires de la voie du glycolate indique que le cycle de Calvin ne peut pas fonctionner á l'obscurité.Les composés synthétisés à l'obscurité suggèrent que du pouvoir réducteur est disponible. Par contre l'ATP ne l'est pas. Ainsi, durant la période de pré-illumination oú la lumière était strictement limitante la disponibilité en ATP serait le premier facteur limitant l'assimilation du CO2.相似文献
3.
Phylogeny of tall fescue and related species using RFLPs 总被引:4,自引:0,他引:4
W. W. Xu D. A. Sleper 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(6-7):685-690
The wild species of tall fescue (Festuca arundinacea var.genuina Schreb.) represent a wide range of genetic variation and constitute potential germplasm for tall fescue improvement. Our objective was to evaluate genome specificity of the previously-identified DNA probes and to examine the phylogenetic relationship of tall fescue with six related species by using RFLP data. A total of 29 DNA probes from aPstI-genomic library of tall fescue were hybridized toEcoRI-orHindIII-digested DNA of 32 plants from sixFestuca species and fromLolium perenne L. Fifteen probes hybridized to all seven species. The remaining 14 probes showed differential hybridization patterns (i.e., ±), especially at the diploid and tetraploid levels. This hybridization pattern reflected genome divergence in these species. The DNA probes will be useful markers in breeding programs involving interspecific and intergeneric hybridization. Cluster analyses were performed using the average genetic distances calculated with the RFLP data from 53 probe-enzyme combinations. Generally, genotypes from the same species were grouped in the same cluster. These data indicated that tall fescue has a close relationship withF. pratensis Huds. (diploid),F. arundinacea var.glaucescens Boiss. (tetraploid), andL. perenne L. (diploid) and thatFestuca pratensis andL. perenne had the closest degree of relationship.This paper is a contribution of the Missouri Agricultural Experimental Station, Journal Series no. 11,798 相似文献
4.
Using an open gas-exchange system, apparent photosynthesis, true photosynthesis (TPS), photorespiration (PR) and dark respiration of sunflower (Helianthus annuus L.) leaves were determined at three temperatures and between 50 and 400 l/l external CO2. The ratio of PR/TPS and the solubility ratio of O2/CO2 in the intercellular spaces both decreased with increasing CO2. The rate of PR was not affected by the CO2 concentration in the leaves and was independent of the solubility ratio of oxygen and CO2 in the leaf cell. At photosynthesis-limiting concentrations of CO2, the ratio of PR/TPS significantly increased from 18 to 30°C and the rate of PR increased from 4.3 mg CO2 dm-2 h-1 at 18°C to 8.6 mg CO2 dm-2 h-1 at 30°C. The specific activity of photorespired CO2 was CO2-dependent but temperature-independent, and the carbon traversing the glycolate pathway appeared to be derived both from recently fixed assimilate and from older reserve materials. It is concluded that PR as a percentage of TPS is affected by the concentrations of O2 and CO2 around the photosynthesizing cells, but the rate of PR may also be controlled by other factors.Abbreviations APS
apparent photosynthesis (net CO2 uptake)
- PR
photorespiration (CO2 evolution in light)
- RuBP
ribulose-1,5-bisphosphate
- TPS
true photosynthesis (true CO2 uptake) 相似文献
5.
Meiotic and isozymic characterization of plants regenerated from euploid and selfed monosomic tall fescue embryos 总被引:3,自引:0,他引:3
L. S. Dahleen G. C. Eizenga 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(1):39-44
Summary Tissue culture of tall fescue (Festuca arundinacea Schreb., 2n=6x=42) would be enhanced by improving the callus induction and plant regeneration efficiency, and evaluating the meiotic and isozymic variation induced by culture. Mature embryos were cultured from four lines of Kenhy tall fescue and from the progeny of three selfed monosomics. Evaluation of six media-auxin combinations showed callus initiation was greatest on SH medium with 2.5 mg/l 2,4,5-T or 7.4 mg/l pCPA, while plant regeneration was greatest on SH medium with 0.5 mg/l 2,4-D. Cytological analyses of 27 plants derived from euploid parents showed a high frequency of aneuploidy (15/27). Chromosome numbers of aneuploids ranged from 36 to 41, with one plant having 80 chromosomes and two plants being asynaptic. Two of ten monosomic-derived plants were euploid, five were monosomic, one was monosomic with a fragment and two were double monosomic. Zymograms of the parents and regenerants were obtained for the enzymes ACPH, ADH, GOT, 6-PGD and PGI. Isozyme variation was observed for two groups of plants derived from the same Kenhy embryos. One group of four monosomic-derived plants differed for the enzymes GOT and ACPH, and all four plants had a PGI pattern. different from that of the parental monosomic plant. This indicated loss of a PGI allele, probably as a result of callus culture.Contribution No. 89-3-141 of the Kentucky Agricultural Experiment Station in cooperation with the USDA-ARS. Part of thesis research for senior author's M. S. degree 相似文献
6.
The [CO2] in the xylem of tree stems is typically two to three orders of magnitude greater than atmospheric [CO2]. In this study, xylem [CO2] was experimentally manipulated in saplings of sycamore (Platanus occidentalis L.) and sweetgum (Liquidambar styraciflua L.) by allowing shoots severed from their root systems to absorb water containing [CO2] ranging from 0.04% to 14%. The effect of xylem [CO2] on CO2 efflux to the atmosphere from uninjured and mechanically injured, i.e., wounded, stems was examined. In both wounded and unwounded stems, and in both species, CO2 efflux was directly proportional to xylem [CO2], and increased 5-fold across the range of xylem [CO2] produced by the [CO2] treatment. Xylem [CO2] explained 76–77% of the variation in pre-wound efflux. After wounding, CO2 efflux increased substantially but remained directly proportional to internal stem [CO2]. These experiments substantiated our previous finding that stem CO2 efflux was directly related to internal xylem [CO2] and expanded our observations to two new species. We conclude that CO2 transported in the xylem may confound measurements of respiration based on CO2 efflux to the atmosphere. This study also provided evidence that the rapid increase in CO2 efflux observed after tissues are excised or injured is likely the result of the rapid diffusion of CO2 from the xylem, rather than an actual increase in the rate of respiration of wounded tissues. 相似文献
7.
Relative importance of short-term environmental interaction and preconditioning to CO2 exchange response was examined in Fragaria ananasa (strawberry, cv. Quinault). Tests included an orthogonal comparison of 15 to 60-min and 6 to 7-h exposures to different levels of temperature (16 to 32°C), photosynthetically active radiation (PAR, 200 to 800 E m2 s-1), and CO2 (300 to 600 l/l) on successive days of study. Plants were otherwise maintained at 21°C, 300 E m2 s-1 PAR and 300–360 l/l CO2 as standard conditions. Treatment was restricted to the mean interval of 14 h daily illumination and the first 3–4 days of each test week over a 12-week cultivation period. CO2 exchange rates were followed with each step-change in environmental level including ascending/descending temperature/PAR within a test period, initial response at standard conditions on successive days of testing, and measurement at reduced O2. Response generally supported prior concepts of leaf biochemical modeling in identifying CO2 fixation as the major site of environmental influence, while overall patterns of whole plant CO2 exchange suggested additional effects for combined environmental factors and preconditioning. These included a positive interaction between temperature and CO2 concentration on photosynthesis at high irradiance and a greater contribution by dark respiration at lower PAR than previously indicated. The further importance of estimating whole plant CO2 exchange from repetitive tests and measurements was evidenced by a high correlation of response to prior treatment both during the daily test period and on consecutive days of testing.Abbreviations C3 plant
a plant in which the product of CO2 fixation is a 3-carbon acid (3-phosphoglyceric acid)
- IRGA
intra-red gas analyzer
- PAR
photosynthetically active radiation
- RH
relative humidity
- RuBisCO
ribulose-1,5-bisphosphate carboxylase/oxygenase
Reference to a company and/or product named by the Department is only for purposes of information and does not imply approval or recommendation of the product to the exclusion of others which may also be suitable. 相似文献
8.
Agrobacterium-mediated high efficiency transformation of tall fescue (Festuca arundinacea) 总被引:3,自引:0,他引:3
Tall fescue (Festuca arundinacea) is the predominant cool-season pasture grass in the USA. Embryogenic calluses were induced from seeds/caryopsis of elite tall fescue cultivars Jesup and Kentucky-31, and were broken up into small pieces and used for Agrobacterium tumefaciens-mediated transformation. Agrobacterium strains LBA4404 and EHA105 harboring pCAMBIA vectors or the super-binary vector pTOK233 were used to infect the embryogenic callus pieces. The number of hygromycin resistant calluses obtained per dish of infected callus pieces was in the range of 2.0-5.8, and the number of transgenic plants recovered per dish of infected callus pieces was in the range of 0.4-1.7. When transformation efficiency was calculated based on the number of transgenic plants recovered and the number of original intact calluses used, the transformation frequency was in the range of 1.9-8.7%. The use of the easily available pCAMBIA vectors could produce equivalent results as the superbinary vector pTOK233. The transgenic nature of the regenerated plants was demonstrated by Southern hybridization analysis using undigested and digested genomic DNA samples. Expression of the transgenes was confirmed by northern hybridization analysis, GUS staining, and detection of GFP signals. Fertile transgenic plants were obtained after vernalization in the greenhouse. Progeny analysis revealed Mendelian inheritance of the transgenes. 相似文献
9.
Taiji Kou Jianguo Zhu Zubin Xie Toshihiro Hasegawa Katia Heiduk 《Plant and Soil》2007,299(1-2):237-249
Soil respiration in a cropland is the sum of heterotrophic (mainly microorganisms) and autotrophic (root) respiration. The
contribution of both these types to soil respiration needs to be understood to evaluate the effects of environmental change
on soil carbon cycling and sequestration. In this paper, the effects of free-air CO2 enrichment (FACE) on hetero- and autotrophic respiration in a wheat field were differentiated and evaluated by a novel split-root
growth and gas collection system. Elevated atmospheric pCO2 of approximately 200 μmol mol−1 above the ambient pCO2 significantly increased soil respiration by 15.1 and 14.8% at high nitrogen (HN) and low nitrogen (LN) application rates,
respectively. The effect of elevated atmospheric pCO2 on root respiration was not consistent across the wheat growth stages. Elevated pCO2 significantly increased and decreased root respiration at the booting-heading stage (middle stage) and the late-filling stage
(late stage), respectively, in HN and LN treatments; however, no significant effect was found at the jointing stage (early
stage). Thus, the effect of increased pCO2 on cumulative root respiration for the entire wheat growing season was not significant. Cumulative root respiration accounted
for approximately 25–30% of cumulative soil respiration in the entire wheat growing season. Consequently, cumulative microbial
respiration (soil respiration minus root respiration) increased by 22.5 and 21.1% due to elevated pCO2 in HN and LN, respectively. High nitrogen application significantly increased root respiration at the late stage under both
elevated pCO2 and ambient pCO2; however, no significant effects were found on cumulative soil respiration, root respiration, and microbial respiration.
These findings suggest that heterotrophic respiration, which is influenced by increased substrate supplies from the plant
to the soil, is the key process to determine C emission from agro-ecosystems with regard to future scenarios of enriched pCO2. 相似文献
10.
We used an advanced radiogasometric method to study the effects of short-term changes in CO2 concentration ([CO2]) on the rates and substrates of photorespiratory and respiratory decarboxylations under steady-state photosynthesis and in the dark. Experiments were carried out on Plantago lanceolata, Poa trivialis, Secale cereale, Triticum aestivum, Helianthus annuus and Arabidopsis thaliana plants. Rates of photorespiration and respiration measured at a low [CO2] (40 micromol mol(-1)) were equal to those at normal [CO2] (360 micromol mol(-1)). Under low [CO2], the substrates of decarboxylation reactions were derived mainly from stored photosynthates, while under normal [CO2] primary photosynthates were preferentially consumed. An increase in [CO2] from 320 to 2300 micromol mol(-1) brought about a fourfold decrease in the rate of photorespiration with a concomitant 50% increase in the rate of respiration in the light. Respiration in the dark did not depend on [CO2] up to 30 mmol mol(-1). A positive correlation was found between the rate of respiration in the dark and the rate of photosynthesis during the preceding light period. The respiratory decarboxylation of stored photosynthates was suppressed by light. The extent of light inhibition decreased with increasing [CO2]; no inhibition was detected at 30 mmol mol(-1) CO2. 相似文献
11.
Wan-Jun Zhang Jiang-Li Dong Ben-Guo Liang Yong-Sheng Jin Tao Wang 《In vitro cellular & developmental biology. Plant》2006,42(2):114-118
Summary We report a protocol for efficient plant regeneration of four tall fescue (Festuca arundinacea Schreb.) cultivars (‘Surpro’, ‘Coronado’, ‘Summer Lawn’, and ‘Fawn’) via somatic embryogenesis. Calli were initiated from
mature seeds grown on modified Murashige and Skoog (MMS) medium supplemented with 7.0mgl−1 (31.7μM) 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.05 mgl−1 (0.23 μM) kinetin (Kin). Calli were maintained and proliferated by subculture at monthly intervals on MMS medium containing 4.5 mgl−1 (20.4 μM) 2,4-D and 0.2mgl−1 (0.9 μM) Kin. Somatic embryos (SE) were induced from seed-derived calli on SE-induction medium (MMS supplemented with 2.0 mgl−1 2,4-D and 0.2mgl−1 Kin). Plantlets were regenerated from somatic embryogenic calli grown on modified SH medium supplemented with 2 mgl−1 Kin. Using this optimized protocol, 78.6–82.3% of mature seeds of all four cultivars produced SE clusters, of which 93.5–95.3%
regenerated into plants within 10 wk. The regenerants showed no phenotypic abnormalities. 相似文献
12.
N. S. Balaur V. A. Vorontsov E. I. Kleiman Yu. D. Ton 《Russian Journal of Plant Physiology》2009,56(3):423-427
A novel technique designed for component monitoring of CO2 exchange in plants is described. The system is based on application of self-clamping leaf chambers connected to an open gas-exchange measuring system and on automatic recording of CO2 concentration. This technique was implemented in a commercially available instrument, PTM-48A Photosynthesis Monitor, which provides for long-term measurements of gas exchange and for discrimination of its separate components. Furthermore, many other plant functions can be monitored during plant growth and development under laboratory, greenhouse, and field conditions. 相似文献
13.
On the assessment of root and soil respiration for soils of different textures: interactions with soil moisture contents and soil CO2 concentrations 总被引:10,自引:0,他引:10
Estimates of root and soil respiration are becoming increasingly important in agricultural and ecological research, but there
is little understanding how soil texture and water content may affect these estimates. We examined the effects of soil texture
on (i) estimated rates of root and soil respiration and (ii) soil CO2 concentrations, during cycles of soil wetting and drying in the citrus rootstock, Volkamer lemon (Citrus volkameriana Tan. and Pasq.). Plants were grown in soil columns filled with three different soil mixtures varying in their sand, silt
and clay content. Root and soil respiration rates, soil water content, plant water uptake and soil CO2 concentrations were measured and dynamic relationships among these variables were developed for each soil texture treatment.
We found that although the different soil textures differed in their plant-soil water relations characteristics, plant growth
was only slightly affected. Root and soil respiration rates were similar under most soil moisture conditions for soils varying
widely in percentages of sand, silt and clay. Only following irrigation did CO2 efflux from the soil surface vary among soils. That is, efflux of CO2 from the soil surface was much more restricted after watering (therefore rendering any respiration measurements inaccurate)
in finer textured soils than in sandy soils because of reduced porosity in the finer textured soils. Accordingly, CO2 reached and maintained the highest concentrations in finer textured soils (> 40 mmol CO2 mol−1). This study revealed that changes in soil moisture can affect interpretations of root and soil measurements based on CO2 efflux, particularly in fine textured soils. The implications of the present findings for field soil CO2 flux measurements are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
Evaluation of soil respiration and soil CO2 concentration in a lowland moist forest in Panama 总被引:2,自引:0,他引:2
T. A. Kursar 《Plant and Soil》1989,113(1):21-29
Soil gas exchange was investigated in a lowland moist forest in Panama. Soil water table level and soil redox potentials indicate that the soils are not waterlogged. Substantial microspatial variation exists for soil respiration and soil CO2 concentration. During the rainy season, soil CO2 at 40 cm below the surface accumulates to 2.3%–4.6% and is correlated with rainfall during the previous two weeks. Temporal changes in soil CO2 are rapid, large and share similar trends between sampling points. Possible effects of soil CO2 changes on plant growth or phenology are discussed. 相似文献
15.
Seedlings (70-d-old) of two tall fescue (Festuca arundinacea Schreb.) genotypes, heat-tolerant Jaguar 3 and heat-sensitive TF 66, were exposed to a high temperature stress of 35/30 °C
(day/night) for 20 d and both light-saturated and CO2-saturated leaf stomatal conductance decreased, especially in TF 66. Higher reductions of quantum efficiency, carboxylation
efficiency and maximum photochemical efficiency of photosystem 2 in dark adapted leaves (measured as Fv/Fm) occurred in TF 66 than in Jaguar 3. High temperature stress increased photorespiration in the two plants, but more in TF
66. Moreover, high temperature stress also reduced the growth, chlorophyll content and caused cell membrane injuries in the
two cultivars, the changes were again more pronounced in TF 66 than in Jaguar 3. 相似文献
16.
A CO2 assay circuit adapted to in vitro culture was designed to investigate CO2 exchanges in test tube-grown Vitis rupestris plantlets. The CO2 concentration of the air in culture tubes was measured by injection of samples in the open circuit. It was observed under the culture conditions used that the CO2 content stabilized during the light phase at 3 times the CO2 compensation point.Measurements of dark respiration under closed circuit conditions at every two-hour interval during the night did not reveal any limiting by lack of the substrate under mixotrophic culture conditions. A mathematical model of the influence of ambient CO2 concentration on net CO2 uptake rates under closed circuit conditions was devised and used to compare net photosynthesis at different lighting levels. Measurement of CO2 evolution into CO2-free air under open circuit conditions revealed a post-illumination burst characteristic of photorespiration which increased with the temperature. 相似文献
17.
High CO2 partial pressure effects on dark and light CO2 fixation and metabolism in Vicia faba leaves
Stomatal opening on Vicia faba can be induced by high CO2 partial pressures (10.2%) in dark as well as in light. Stomatal aperture was measured in both cases with a hydrogen porometer. The distribution of 14C among early products of photosynthesis was studied. Comparisons are made with carboxylations occurring when stomata were open in the dark with CO2-free air and in light with 0.034% CO2. Results showed that in high CO2 partial pressure in light, less radioactivity was incorporated in Calvin cycle intermediates and more in sucrose. carboxylations and photorespiration seemed to be inhibited. In the dark in both CO2 conditions, 14C incorporation was found in malate and aspartate but also in serine and glycerate in high CO2 conditions. In light these changes in metabolic pathways may be related with the deleterious effects recorded on leaves after long-term expositions to high partial pressure of CO2.Abbreviations DHAP
dihydroxyacetone phosphate
- PEP
phosphonenolpyruvate
- PEPCK
phosphonenolpyruvatecarboxykinase
- PGA
3-phosphoglyceric acid
- RUBPc
ribulose 1,5-bisphosphate carboxylase 相似文献
18.
Bouma Tjeerd J. Nielsen Kai L. Eissenstat David M. Lynch Jonathan P. 《Plant and Soil》1997,195(2):221-232
Little information is available on the variability of the dynamics of the actual and observed root respiration rate in relation to abiotic factors. In this study, we describe I) interactions between soil CO2 concentration, temperature, soil water content and root respiration, and II) the effect of short-term fluctuations of these three environmental factors on the relation between actual and observed root respiration rates. We designed an automated, open, gas-exchange system that allows continuous measurements on 12 chambers with intact roots in soil. By using three distinct chamber designs with each a different path for the air flow, we were able to measure root respiration over a 50-fold range of soil CO2 concentrations (400 to 25000 ppm) and to separate the effect of irrigation on observed vs. actual root respiration rate. All respiration measurements were made on one-year-old citrus seedlings in sterilized sandy soil with minimal organic material.Root respiration was strongly affected by diurnal fluctuations in temperature (Q10 = 2), which agrees well with the literature. In contrast to earlier findings for Douglas-fir (Qi et al., 1994), root respiration rates of citrus were not affected by soil CO2 concentrations (400 to 25000 ppm CO2; pH around 6). Soil CO2 was strongly affected by soil water content but not by respiration measurements, unless the air flow for root respiration measurements was directed through the soil. The latter method of measuring root respiration reduced soil CO2 concentration to that of incoming air. Irrigation caused a temporary reduction in CO2 diffusion, decreasing the observed respiration rates obtained by techniques that depended on diffusion. This apparent drop in respiration rate did not occur if the air flow was directed through the soil. Our dynamic data are used to indicate the optimal method of measuring root respiration in soil, in relation to the objectives and limitations of the experimental conditions. 相似文献
19.
G. Spangenberg M. P. Vallés Z. Y. Wang P. Montavon J. Nagel I. Potrykus 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(5):509-519
Intergeneric asymmetric somatic hybrids have been obtained by the fusion of metabolically inactivated protoplasts from embryogenic suspension cultures ofFestuca arundinacea (recipient) and protoplasts from a non-morphogenic cell suspension ofLolium multiflorum (donor) irradiated with 10, 25, 50, 100, 250 and 500 Gy of X-rays. Regenerating calli led to the recovery of genotypically and phenotypically different asymmetric somatic hybridFestulolium plants. The genome composition of the asymmetric somatic hybrid clones was characterized by quantitative dot-blot hybridizations using dispersed repetitive DNA sequences specific to tall fescue and Italian ryegrass. Data from dot-blot hybridizations using two cloned Italian ryegrass-specific sequences as probes showed that irradiation favoured a unidirectional elimination of most or part of the donor chromosomes in asymmetric somatic hybrid clones obtained from fusion experiments using donor protoplasts irradiated at doses 250 Gy. Irradiation of cells of the donor parent with 500 Gy prior to protoplast fusion produced highly asymmetric nuclear hybrids with over 80% elimination of the donor genome as well as clones showing a complete loss of donor chromosomes. Further information on the degree of asymmetry in regenerated hybrid plants was obtained from chromosomal analysis including in situ hybridizations withL. multiflorum-specific repetitive sequences. A Southern blot hybridization analysis using one chloroplast and six mitochondrial-specific probes revealed preferentially recipient-type organelles in asymmetric somatic hybrid clones obtained from fusion experiments with donor protoplasts irradiated with doses higher than 100 Gy. It is concluded that the irradiation of donor cells before fusion at different doses can be used for producing both nuclear hybrids with limited donor DNA elimination or highly asymmetric nuclear hybrid plants in an intergeneric graminaceous combination. For a wide range of radiation doses tested (25–250Gy), the degree of the species-specific genome elimination from the irradiated partner seems not to be dose dependent. A bias towards recipient-type organelles was apparent when extensive donor nuclear genome elimination occurred.Abbreviations cpDNA
Chloroplast DNA
- 2, 4-D
2,4-dichlorophenoxyacetic acid
- FDA
fluorescein diacetate
- IOA
iodoacetamide
- mtDNA
mitochondrial DNA
- RFLP
restriction fragment length polymorphism 相似文献
20.
M. Mousseau 《Photosynthesis research》1981,2(2):85-94
The effect of a shift from a long to a short photoperiod on CO2 exchange of Chenopodium polyspermum was studied. Equal quantities of photosynthetic energy were given daily to the plants, long photoperiods being produced by low intensity red light extension. A change in the photoperiod was shown to affect the pattern of CO2 loss at the beginning of the night period and the onset of CO2 intake at the beginning of day time. These events seem to be under phytochrome control.The photoperiod had an effect on the slope of the CO2 curve of photosynthesis, efficiency of photosynthesis being increased after a short day. This effect was not due to a variation in the stomatal resistance.The action of O2 concentration on photosynthesis (Warburg effect) was affected by the photoperiodic treatment, being less important after a long day than after a short day.Involvement of phytochrome in photosynthetic efficiency and photorespiration is discussed.
Résumé On étudie l'effet d'une variation de photopériode sur les échanges de CO2 de Chenopodium polyspermum. Les plantes reçoivent la même quantité d'énergie utilisable par la photosynthèse, l'allongement de la photopériode étant obtenu par addition au cours de la nuit de lumière rouge de faible intensité.Un changement de photopériode affecte à court terme le déroulement de la chute de respiration en début de nuit ainsi que la mise en route de la photosynthèse le jour suivant.Une variation de traitement photopériodique modifie l'efficience de la photosynthèse: la pente de la courbe de photosynthèse en fonction du CO2 est plus élevée après un jour court. Cet effet n'est pas dú à une variation de résistance stomatique.L'action de la concentration en oxygène de l'air sur la photosynthèse (effet Warburg) est également affectée par le traitement photopériodique: elle est moins importante après un jour long qu'après un jour court.On discute l'influence éventuelle du phytochrome sur l'efficience de la photosynthèse et la photorespiration.相似文献