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1.
Environmental Effects on the Diurnal Accumulation of 45Ca by Young Fruit and Leaves of Tomato Plants 总被引:1,自引:0,他引:1
Diurnal uptake and distribution of 45Ca in young fruiting tomatoplants were assessed 12 or 24 h after 45Ca was applied to thenutrient solution at the beginning of either the light (12 h)or the dark (12 h) period. During the experiment, the salinityof the nutrient solution (measured as electrical conductivity,EC) was either 2·5 or 17 mS cm1 and the relativehumidity (measured as vapour pressure deficit, VPD) was either0·2 or 0·6 kPa The uptake of 45Ca by a tomato plant over 12 h was higher inthe light than in the dark but the difference was less at lowhumidity. More 45Ca was transported from the roots to the shootin the light than in the dark. More than half of the 45Ca inthe shoot was accumulated by the stem; the proportion of 45Cain the stem was greater in the dark and was further enhancedby high humidity to more than 80% of the 45Ca in the shoot.The accumulation of 45Ca by the fruit truss in the dark wasgreater than in the light in all experimental conditions. Underlow humidity the accumulation of 45Ca by young leaves was similarin both light and dark. In high humidity there was considerablyless accumulation of 45Ca by the young leaves in the dark The uptake of 45Ca continued over 24 h but the transport of45Ca to individual organs in the second 12 h period was affectedby both light and humidity. Some of the 45Ca accumulated byyoung leaves and fruit in the second period appears to havebeen derived from 45Ca released from the xylem wall along thetransport pathway in the stem The roles of root pressure and transpiration in the diurnalaccumulation of calcium in young fruit and leaves are discussed Calcium, diurnal translocation, tomato, young fruit and leaves 相似文献
2.
Diurnal variations in the pattern of movement of sugars, water,and ions into developing tubers of the potato (Solanum tuberosumL.) were investigated. It was demonstrated using a recordingbalance that large increases in the fresh weight of tubers occurduring a dark period of reduced transpiration. Movement of assimilated14C did not reflect similar large changes and much of the weightchange observed is considered to be fluctuations in tuber watercontent. This water was shown to be moving predominantly throughthe xylem of the stolon by introducing labelled ions, 32P and89Sr into the plants. 32P, which moves in both xylem and phloem,was transported to the tuber at a constant rate whereas 89Sr,which behaves like calcium and is relatively immobile in thephloem, only moved into the tuber during the dark period. As well as the over-all long-term diurnal fluctuations severalsmaller rapid changes were recorded in the rate of water movement.Switching from darkness to light caused a transient increasefollowed by a rapid decrease in tuber weight. Switching fromlight to darkness caused a rapid increase in tuber weight. Insome experiments small oscillations in tuber weight were recorded.The possibility of these oscillations being directly relatedto cyclic changes in transpiration is considered. The resultsare discussed in relation to solute movement within plants. 相似文献
3.
Studies have been made of the distribution of 45Ca, 42K, totalK+ and 32P between the concave and convex sides of segmentsof hypocotyl of Helianthus annuus and coleoptiles of Zea maysduring curvatures induced by gravity, unilateral illuminationor unilateral applications of indol-3yl acetic acid (IAA). Theelements were fed to the roots of seedlings for a 34h pretreatment period. Distributions in segments in intact seedlingswere compared with those in explanted segments deprived of acontinuing supply of the element concerned in order to separatepossible differential transport of the element from the rootsfrom any real movement across the organ from side to side. Withall three treatments, and in both explants and intact plants,45Ca concentrations (on both fwt and dwt bases) were higheron the convex side. There was evidence of differential transportto the two sides and also of a direct movement across the parenchymafrom one side to the other. In organs where curvature was inhibitedby low temperatures (4 °C in geotropic experiments) or bythe antitropistic agent, N-1-naphthylphthalamic acid, no concentrationdifferences arose between the two sides. After the tropic stimulithe onset of the concentration differences preceded the onsetof curvature significantly, indicating that those differenceswere not caused by differential growth of the organ. The diuretic,mersalyl, applied unilaterally produced differences in elementconcentration of the same order and kind as similar treatmentwith IAA, but caused no growth curvatures. It is concluded that the movement of elements in tropicallycurving tissues, although apparently obligately-linked withcurvature, is not the result of that curvature or its cause,but is in some as yet undefined way an outcome of auxin gradientsin the tissue. 相似文献
4.
In vigorously growing shoots of apple and plum 14C-assimilateswere translocated from a fed leaf to particularsectors of other leaves in a distribution pattern associatedwith the phyllotaxis; the same sectorial and distribution patternswere produced by 32P phosphate solution taken into the shootthrough a cut petiole. The frequency with which a given sectorialpattern occurred at a particular position on the phyllotacticspiral was ascertained. Such patterns were not observed abovethe third rolled leaf in the apple shoot apex. Killing the phloem in the petiole prevented egress of labelledassimilate but not of 32P solution. Barkringing above the sourceleaf reduced, but did not completely prevent, assimilate movementup the stem, suggesting some translocation in the xylem. Distribution of label from 45CaCl2, 86RbCl and [3H]asparagine,incorporated through cut petioles, did not follow the same patternas label from 32P solutions. Malus pumila Mill., apple, Prunus domestica L., Prunus insititia. L., leaf plum, patterns, transport of radioisotopes, vascular phyllotaxis 相似文献
5.
The Role of Phloem Transport in the Translocation of Sucrose Along the Stem of Carnation Cut Flowers
The pathway and distribution of 14C-sugars in flower parts havebeen examined to find out in which tissue sugars are translocatedin the stem of the cut carnation; 14C-sucrose or 14C-glucosewas supplied at the base of the cut stem from a feeding solutionand the localization and chemical nature of the carbon-14 recoveredfrom flower parts were investigated. By reducing the rate oftranspiration it was found that the uptake of feeding solutionwas also reduced, but the distribution of absorbed 14C-sucrosein the flower parts was different from that which would be expectedif sucrose moved exclusively in the transpiration stream. Autoradiographsdemonstrated that 14C absorbed from the feeding solution as14C-sucrose appeared in both xylem and phloem but predominantlyin the latter; girdling failed to stop the translocation ofthe absorbed 14C-sucrose. Results of experiments with 14C-sucroseand 14C-glucose showed that sucrose was the mobile sugar andthat glucose was converted to sucrose before it was translocated.It was concluded that the translocation of sucrose absorbedfrom the feeding solution takes place both in xylem and phloemand is regulated by a mechanism involving the loading and translocationof sucrose in the phloem. 相似文献
6.
The rate of uptake of 32P from labelled NaH2PO4 solutions sprayedon to one leaf of swedes (Brassica napus) or French beans (Phaseolusvulgaris) was rapid during the first few hours and fell to zeroafter 4 days. 22P was detected in the root after 3 hours andcontinued to move out of the treated leaf for at least 6 daysafter application. A larger fraction of the applied 32P wasabsorbed from repeated than from a single spraying. Swedes absorbed more 32P from a single application to the lowersurface than to the upper surface of the leaf. Doubling theconcentration of the spray caused a small increase in the percentageof applied 22P that was absorbed. Absorption by French-beanleaves decreased slightly when the area sprayed with a constantamount of 32P was doubled, and decreased with increasing ageof leaf. Increasing the phosphorus supply to the roots of swedesaffected neither the initial rate nor the total amount of 32Puptake by the leaves but decreased the quantity of 32P thatwas translocated out of the treated leaf. Increasing the relative humidity of the air around the plantsalso increased32P uptake. Shading usually decreased uptake andalways decreased translocation. Rewetting the leaf to whichthe 32P had been applied, with water or sucrose solution, hadvariable effects. The significance of the results is discussed. 相似文献
7.
Dynamics of Nutrient Translocation in Stemwood across an Age Series of a Eucalyptus Hybrid 总被引:1,自引:0,他引:1
Laclau Jean-Paul; Bouillet Jean-Pierre; Ranger Jacques; Joffre Richard; Gouma Raphael; Saya Aubin 《Annals of botany》2001,88(6):1079-1092
Despite the continuous nature of growth of eucalyptus hybridsin Congo, taper functions fitted to stem profiles of one clonethroughout stand development, combined with annual tree measurements,made it possible to locate accurately the position of annualrings in stems. Annual rings were identified on discs of woodsampled every 4 m in four trees cut from 1-, 2-, 3-, 4-, 5-,6- and 7-year-old stands. Chemical analysis, performed individuallyfor each ring per level and per tree sampled, made it possibleto quantify the changes in nutrient content of the rings duringstand development. Nutrient translocation in stemwood was thuscalculated in a stepwise manner between trees of two successiveages. The cumulated nutrient translocations in stemwood fromthe 1-year-old stage to the 6-year-old stage amounted to 18·5kg ha-1N, 4·2 kg ha-1P, 38·8 kg ha-1K, 1·5kg ha-1Ca and 3·2 kg ha-1Mg. They represented 11, 18,121, 6, and 15% of the amounts of N, P, K, Ca and Mg accumulatedin stemwood, respectively, at the 7-year-old stage (loggingage). Negative translocations of N, P, Ca and Mg in stemwoodbetween 6 and 7 years might indicate an improvement in the nutritivestatus of the stand at the end of the rotation. Much translocationof K in stemwood suggests that this process might be involvedin the high use efficiency of this element. Copyright 2001 Annalsof Botany Company Translocation, stemwood, ring, nutrient, Eucalyptus, age series 相似文献
8.
A method of obtaining sterile pea stem sections has been developedand the effect of auxin on RNA metabolism has been investigatedusing aseptic techniques. Auxin rapidly stimulated 32P-incorporationinto ethanol precipitated nucleic acid preparations. Subsequentexperiments showed that the bulk of the 32P in these preparationswas present in a non-nucleic acid component which could be separatedfrom the nucleic acids by combined CM cellulose-Sephadex chromatography.This method of separation was used to show that auxin treatmentdoes not appear to stimulate RNA synthesis before stimulatingextension growth. 相似文献
9.
Fluid extracted from grapevine shoots by suction contained upto 0.2 per cent (w/v) of sugar. The total sugar concentrationand the relative concentrations of sucrose, glucose, and fructosechanged along the length of a shoot. Whereas sucrose is absentfrom or present only in traces in fluid bleeding from cut stumps,it was found to be a major constituent in fluid extracted fromsections of wood by suction. 14C-glucose administered to thewood of an excised shoot moved up in the transpiration stream,moved laterally, into the bark, and was partly converted tosucrose and fructose. When 14CO2 was supplied to a leaf of anintact vine, radioactive sugars were found in the fluid afterwardsextracted from the wood by suction. When a ring of bark wasremoved from the stem at a point above the 14CO2-treated leafmost of the 14C in the bark, wood, and extracted fluid belowthe ring was in the form of sugar but 14C in tissues above thering was mainly in organic acids and amino acids. It is suggestedthat a barrier within the wood prevents diffusion of sugarsinto the transpiration stream, and that the fluid extractedfrom the wood by suction cannot be regarded as ascending sapsince it contains considerable amounts of non-moving material. 相似文献
10.
To elucidate the mechanism of the phosphorylation of myo-inositolin the process of phytate formation, feeding experiments oforthophosphate-32P and myo-inositol-3H in the ripening grainsof rice and wheat were performed. It was found that 32P and3H were incorporated into myo-inositol mono- and hexa-phosphates.The same results were obtained when a mixture of "cold" myo-inositolpolyphosphates was administered to the grains before feedingphosphate-32P. Based on these results it is concluded that phosphorylationof free myo-myo-inositol in the formation of phytate does nottake place in a stepwise fashion but may proceed through anunknown myo-inositol derivative. (Received August 2, 1967; ) 相似文献
11.
Inherent differences in the responses of stomata on abaxialand adaxial epidermal surfaces of leaves of Commelina communishave previously been suggested to be due to differences in theconcentrations of apoplastic Ca. Adaxial stomata have also beenreported to be more sensitive than abaxial stomata to appliedabscisic acid (ABA). The aims of these experiments were to determinethe validity of these conclusions and to see if xylem sap Cahas a role in determining the response of stomata to ABA. It can be shown from measurements of relative stomatal resistance(determined with a viscous flow porometer) and stomatal conductancethat stomata were more open in plants grown on 8-0 mol m3Ca, than with those grown on 2-0 mol m3 Ca. When attachedleaves were fed with ABA via the transpiration stream neitherthe extent nor the rate with which conductance declined wasdependent on Ca nutrition. The extent of Ca accumulation within both epidermes was relatedto the concentration of Ca in the rhizosphere and in the xylemsap. It did not, however, appear to reflect the apparent differencesin the flux of the transpiration stream between the two epidermes.Plants growing at the lower Ca concentration accumulated proportionallymore epidermal Ca relative to Ca in xylem sap. The evidencepresented suggests that Ca movement from the xylem to the epidermiscannot be simply described by a mass flow model, and that thedistribution of Ca is not an adequate explanation of the differencesin the behaviour of adaxial and abaxial stomata. The potentialrole for changes in xylem sap Ca to act as a regulator of stomatalbehaviour are discussed. Key words: Abscisic acid, calcium, Commelina communis L., stomatal conductance 相似文献
12.
Translocation of Calcium in Relation to Tomato Fruit Growth 总被引:5,自引:1,他引:4
Regulation of the uptake and distribution of calcium in thetomato plant was investigated in plants grown in recirculatingnutrient solutions at electrical conductivities of 2,7,12 and17 millisiemens (mS). Despite an increased calcium content inthe nutrient solution at high conductivity (717 mS),the accumulation of calcium by fruit was progressively reducedby increasing salinity, particularly in the distal half. Theincidence of blossom-end rot in fruit (BER) also increased withsalinity. The uptake of water and 45Ca by plants was substantially reducedin the high salinity treatment (17 mS) and, to a lesser extent,by high relative humidity (90 per cent r.h. at 20 °C). Further,the translocation of 45Ca from roots to shoots was reduced byhigh salinity, while the percentage distribution of 45Ca tothe apex was reduced by high humidity. Only approx. 2 per centof the 45Ca taken up by a plant was imported by the truss. The uptake of 45Ca and its distribution among pedicel, calyxand berry by detached fruit in 24 h showed that fruit from highsalinity plants had a reduced uptake and a lower accumulationof 45 Ca in the berry than in the calyx. In addition, plants grown at high conductivity had a lower rateof xylem sap exudation from decapitated plants. The fruit ofthese plants had a smaller xylem cross-sectional area in thefruit pedicel and a smaller calyx than those of the low conductivitytreatment. Calcium, translocation, tomato, fruit, blossom-end rot 相似文献
13.
The effects of a deficiency of N, P or K on DNA and RNA synthesisas evidenced by 32P incorporation in TN-1 rice plants were studied.Deficiency effects were more marked in shoot and root tissuesat the l/9th level of the element than at the l/3rd level withrespect to both the content and incorporation of 32P in nucleicacids. The effects were marked on the 43rd day; the plants hadrecovered considerably by the 68th day, but a marked declinewas observed again on the 97th day at the time of flowering.The decrease in 32P incorporation was evident both on a perplant and a per unit weight basis, but it was more prominentin the former. Although 32P uptake was reduced, this reductionwas less than that of 32P incorporation in the nucleic acids.Separation of the RNA fractions revealed that all the fractionswere affected. Deficiency effects also enhanced DNase activity,particularly when there was a K deficiency, but RNase activitywas little affected.
1This work was supported by a grant from the Department of AtomicEnergy, Government of India.
2Central Sericulture Research Institute Berhampore, West Bengal,India. (Received May 27, 1980; ) 相似文献
14.
The effects of a deficiency of N, P or K on DNA and RNA synthesisas evidenced by 32P incorporation in TN-1 rice plants were studied.Deficiency effects were more marked in shoot and root tissuesat the l/9th level of the element than at the l/3rd level withrespect to both the content and incorporation of 32P in nucleicacids. The effects were marked on the 43rd day; the plants hadrecovered considerably by the 68th day, but a marked declinewas observed again on the 97th day at the time of flowering.The decrease in 32P incorporation was evident both on a perplant and a per unit weight basis, but it was more prominentin the former. Although 32P uptake was reduced, this reductionwas less than that of 32P incorporation in the nucleic acids.Separation of the RNA fractions revealed that all the fractionswere affected. Deficiency effects also enhanced DNase activity,particularly when there was a K deficiency, but RNase activitywas little affected.
1This work was supported by a grant from the Department of AtomicEnergy, Government of India.
2Central Sericulture Research Institute Berhampore, West Bengal,India. (Received May 27, 1980; ) 相似文献
15.
32P incorporation into the protein fraction of chloroplast fragmentsby short illumination was investigated under various phosphorylatingconditions. 32P incorporation was generally accompanied by cyclic and non-cyclicphotophosphorylations and also by formation of a high energyintermediate "XE". However, the addition of a DPIP-ascorbatecouple caused inhibition of 32P incorporation, while ATP formationproceeded. Effects of inhibitors and uncouplers of photophosphorylationon the formation of protein-bound 32P were generally similarto those on ATP formation. AT32P was not utilized for protein-bound 32P formation in thedark by chloroplast fragments, but its radioactivity was transferredinto the chloroplast protein fraction in the light. Oligomycininhibited ATP formation but did not inhibit protein-bound 32Pformation. m-Cl-CCP blocked both reactions. This suggests thatprotein-bound 32P is not an actual intermediate in the phosphorylativeprocess leading to formation of ATP. It is probably formed ona side pathway from an intermediate of ATP formation. Analyses of protein-bound 32P after digestion with proteaseand lipase showed that the 32P incorporated was bound to peptidesin chloroplast lamellae. The possible form of this bound 32Pis discussed. (Received November 22, 1971; ) 相似文献
16.
植物根系水力再分配(Hydraulic redistribution)是近几年提出的对植物根系水力提升现象一种更准确的描述。Ryel等(2002)建立的根系水力再分配模型(以下简称Ryel模型)模拟结果表明根系水力再分配是土壤水分动态的一个重要组成部分。该文基于Ryel模型,对模型中涉及的重要参数进行敏感性分析,更准确地阐述参数变化下根系水力再分配模型的行为动态,从而定量分析环境及植物自身等因素对根系水力再分配的影响。Ryel模型时间尺度和土层厚度的设定限制了模型的应用,该文通过参数调整,将模型从时间尺度为小时、土层厚度均一转换到时间尺度为天、土层厚度不等,并应用到内蒙古皇甫川流域。 相似文献
17.
A technique is described for collecting bleeding saps from thepetioles of defoliated plants of the field pea. Analytical studiesand 14CO2-feeding experiments indicate that these saps are physicallyrelated to the fluids delivered to the xylem by the nodulatedroot. There is a progressive decrease in the concentration ofamino-nitrogen in the bleeding saps recovered from the successivepetioles up a stem. This decrease is manifest at any time ofthe day or night and is evident in all ages of plants. It issuggested that it results from the accumulation of a proportionof the incoming amino-acids and amides in living tissues ofthe stem. As the stem ages, it appears to become less effectivein abstracting materials from the xylem. Stem tissues oftenshow a more intensive uptake of asparagine than of other constituentssuch as aspartic acid, glutamine, and homoserine. The abovestudies suggest that much of the nitrogen coming from the rootis immediately sequestered by the lower half of the shoot. Asimilar effect is observed if 14Clabelled bleeding sap is fedto complete, unlabelled shoots via the transpiration stream. 相似文献
18.
Tomato fruit grown in diurnally fluctuating salinities (8 mScm1 during the day and 3 mS cm1 at night; 8/3mS cm1), accumulated the same amount of dry matter andmagnesium (Mg) as those in constant 3 or 8 mS cm1, butan intermediate amount of calcium (Ca). Raising the salinityof the nutrient solution by enriching with macronutrients orby adding NaCl had similar effects. The uptake of 45Ca by tomato plants during the day was greaterthan at night and was reduced by salinity in both periods. Whilethe uptake of 45Ca by 8/3 mS plants at night was similar tothat of 3 mS plants, the daily uptake was less than that in3 and 5.5 mS plants. The Ca content of tomato fruit increased with truss number at3 and 5.5 mS cm1 but not at 8/3 and 8 mS cm1.Within the same truss, the distal fruit had a lower Ca contentbut higher Mg content than the proximal fruit. The reductionin Ca content of the distal fruit at 8/3 mS cm1 was similarto that at 5.5 mS cm1. The Ca content of the tissue atthe distal end of the 8/3 mS fruit was lower than that of the5.5 mS fruit. Similarly, the distribution of 45Ca to the distalhalf of the detached 8/3 mS fruit was less than that of 5.5mS fruit. A reduced uptake and inadequate distribution of Cato the truss and to the distal end of the 8/3 mS fruit werethe main causes of these differences. Lycopersicon esculentum(Mill.), tomato, fruit, calcium, magnesium, diurnal salinity 相似文献
19.
Endothelin-1 activates phospholipases and channels at similar concentrations in porcine coronary arteries 总被引:1,自引:0,他引:1
Jones Allan W.; Magliola Lawrence; Waters Carrie B.; Rubin Leona J. 《American journal of physiology. Cell physiology》1998,274(6):C1583
Sensitivity of endothelin-1 (ET-1)-ion channel interactions hasbeen proposed to exceed that of ET-1-phospholipase activation invascular smooth muscle. We wanted to determine whether short-circuiting ion channels with staphylococcal -toxin pores would shift the ET-1-force relation to the right as predicted from the above proposal. Medium size porcine coronary arteries (outer diameter 0.7-1.5 mm)were mounted on isometric force transducers. ET-1 concentration response curves were compared between intact rings and those subjected to -toxin treatment with Ca buffered at 0.1 µM. TheEC50 for treated rings (1.5 ± 1.0 nM, n = 5 pigs) was similar tothat for intact rings (1.9 ± 0.4 nM). The Ca sensitivity of the-toxin-treated rings(EC50 = 0.43 ± 0.08 µM) was similar to that reported by other laboratories for intact and-toxin-treated arteries and was shifted eightfold to the left by ahigh concentration of ET-1 (10 nM). Measurements of[32P]phosphatidic acid([32P]PA) levels wereused to evaluate phospholipase activity in intact arteries. The timecourses for [32P]PAproduction and contraction were similar in response to high (100 nM)and to low (1 nM) ET-1. Significant increases in both steady-statecontraction and[32P]PA occurred overa wide range of ET-1 concentrations tested (0.3-100 nM). Ourfindings support the concept that ET-1-phospholipase coupling isoperative over the whole concentration range that induces contractileresponses. It is suggested that both Ca entry and Ca sensitizationprocesses are activated by ET-1 at low concentrations (<EC50) and that bothprocesses contribute significantly to the integrated response. 相似文献
20.
Factors Affecting Calcium Transport and Basipetal IAA Movement in Tomato Fruit in Relation to Blossom-end Rot 总被引:1,自引:0,他引:1
Factors affecting the uptake and distribution of calcium (Ca)by detached tomato (Lycopersicon esculentum Mill.) fruit wereinvestigated in seven cultivars with different susceptibilitiesto blossom-end rot (BER), a physiological disorder caused byCa deficiency. Plants were grown with different levels of salinityin the root zone or under shade to induce BER. In addition,fruit grown at different salinities were treated with CME, aninhibitor of auxin transport to alter IAA movement. The basipetalmovement of indole-3-acetic acid (IAA) out of detached fruit(i.e. IAA efflux) was determined concurrently with 45Ca uptaketo assess the possible involvement of IAA in Ca import or theincidence of BER. High salinity in the root zone during fruitdevelopment decreased both the uptake and distribution of 43Cato the blossom-end of the detached fruit. Shading and the applicationof CME reduced 45Ca uptake to a lesser extent. IAA efflux, however,was not consistently reduced by these treatments. Neither theuptake and transport of 45Ca within, nor the efflux of IAA from,detached fruit was related to the cultivar susceptibility toBER. The proposed role of IAA on the uptake and distributionof Ca by tomato fruit is assessed. Key words: Tomato, calcium, IAA, blossom-end rot, salinity 相似文献