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1.
DAVIES  H. V.; VIOLA  R. 《Annals of botany》1988,61(6):689-693
The treatment of potato tubers with 150 µmol dm–3gibberellic acid (GA3) stimulated starch breakdown and hexoseaccumulation in tuber tissues and the transfer of dry matterto stems. These effects could not be accounted for by enhancedactivities of starch phosphorylase, amylase and acid invertase.Indeed enzyme activities either declined or remained relativelyconstant as starch degradation and hexose accumulation proceeded.Changes in the rate of starch depletion were related to changesin sink strength and sink type, the onset of tuber initiationin controls causing the rate of starch degradation to exceedthat in GA3-treated tissues, in which tuberization was inhibited. Solanum tuberosum L., gibberellic acid, starch breakdown  相似文献   

2.
Wounding of quiescent white potato tuber tissue enhances chromatin-boundprotein phosphokinase activity, which exhibits two distinctphases during wound-healing. A moderate activation of the enzymesup to 20 hr after injury is followed by a dramatic increasein activity with a peak at 50 hr. This time-course resemblesthat of chromatinbound DNA-dependent RNA polymerase with a peakin activity at about 48 hr after wounding. The kinases phosphorylateendogenous proteins as well as added histones, phosvitin andcasein. The incorporated phosphate is stable under standardassay conditions, indicating the absence of protein phosphatases.Sensitivity of the incorporated phosphate toward trypsin andalkali, but not DNase, RNase, hydroxylamine or succinic acidpoints to seryl- and threonyl-bonds and proteins as acceptormolecules. Kinases from resting tissues are only weakly stimulatedeven by 100 mM MgCl2, those from wounded tissues exhibit pronouncedMg$$-optima at 5–10 mM with endogenous proteins, phosvitinand casein and 50 mM MgCl2 with histones. Wounding also increasesthe sensitivity of the kinases toward p-hydroxymercuribenzoate. Chromatin preparations from both resting and wounded tissuescontain about 40 protein bands after polyacrylamide disc gelelectrophoresis. In vitro phosphorylation of these proteinsin chromatin from quiescent tissues is comparably low and uniform.Wounding induces changes in the protein and phosphorylationpattern with a general enhancement of phosphorylative capacityand preferential phosphorylation of low molecular weight proteins. (Received August 10, 1981; Accepted November 18, 1981)  相似文献   

3.
MENZEL  C. M. 《Annals of botany》1983,52(5):697-702
Warm temperatures (35°C day/30°C night) which inhibittuberization in potato (Solanum tuberosum L., cv. Sebago) increasedgibberellin activity in crude extracts from buds, but not frommature leaves, as determined by the lettuce hypocotyl bioassay.Changes in the growth of tubers and stolons indicate the occurrenceof basipetal movement of GA3 applied to the terminal bud ora mature leaf. 14C labelling from GA3 or mevalonic acid injectedjust below the terminal bud was recovered in the lower shoot,stolons and tubers, but the amount transported was greater atcool temperatures (20/15°C). It is concluded that high temperaturespromote the synthesis of gibberellin in the buds rather thantransport to the stolons. Solanum tuberosum L., potato, tuberization, gibberellin  相似文献   

4.
Translocation of Assimilates Within and Between Potato Stems   总被引:2,自引:0,他引:2  
Three aspects of translocation in potato were examined: (i)translocation within stems (ii) translocation between individualstems of a plant (iii) translocation between tubers followinginjection of 14C sucrose into a single daughter tuber. Assimilatesexported from single leaves of evenly illuminated potato stemsremained confined to the same side of the stem as the sourceleaf in a pattern consistent with the internal arrangement ofvascular bundles in the stem, and tubers borne on stolons verticallybelow the source leaf contained higher concentrations of 14Cthan those on the opposite side. Consequently 14C import intothe tubers bore little relationship to tuber growth rates. However,alteration of source/sink relations by pruning stems to a singlesouce leaf resulted in an even distribution of 14C throughoutthe vascular bundles of the stem and 14C import into the tubersbore a stronger relationship to tuber growth rates than to thephyllotactic relationship of the tubers with the source leaf. Labelling one stem of a potato plant resulted in little or nomovement of 14C into tubers on other unlabelled stems. However,removal of the unlabelled stems at ground level induced a significantmovement of 14C from the labelled stem to the tubers on unlabelledstems, this movement occurring via the mother tuber. Shadingthe unlabelled stems had less effect than stem removal. 14C sucrose injected into single daughter tubers was translocatedto other tubers on the same stem and also to tubers on a secondstem at the opposite end of the mother tuber. The sucrose wasconverted to starch in these tubers. The results favour the view that each potato stem functionsas an independent unit with potential for assimilate redistributionwithin a stem but with little or no carbon exchange occurringbetween stems, unless under severely altered source/sink patterns. Assimilates, 14C, autoradiography, potato (Solanum tuberosum L.), tuber growth  相似文献   

5.
Polyacrylamide gel electrophoretic patterns of soluble proteinsfrom intact potato tubers and from wounded tuber tissue wereidentical. The patterns from diseased tissue showed some minordifferences not before 3–4 days after inoculation. Itis concluded that primarily proteins of minor fractions areinvolved in protein synthesis after wounding or infection. (Received March 22, 1969; )  相似文献   

6.
Potato plants (Solanum tuberosum L.) were grown in water culture.About 14 d after tuber initiation no significant differenceswere found between apical and basal tuber parts in 14C-uptakeand partitioning into various fractions from 14C-labelled photosynthate.Thus, the fresh weight of these tubers could be used as a parameterfor the sink size. The 14C-content per tuber (sink strength)20 h after 14CO2-supply to the foliage was significantly correlatedwith the tuber fresh weight. No correlation was found betweenthe 14C-concentration of the tuber (sink activity; ct. ming fr. wt.) and tuber fresh weight. Consequently, tuberfresh weight (sink size) per se must have been a factor whichinfluenced sink strength. Stolon parameters characterizing theirgrowth prior to tuber initiation (e.g. stolon volume) and theircapacity for photosynthate transport (diameter, length) weremeasured at the time of tuber initiation. Significant correlationswere found between these stolon parameters and subsequent growthof individual tubers. Anatomical studies on the proportion ofvarious tissues in the cross sectional area of stolons supportthe idea of a negative relation between growth of individualtubers and transport resistance in the phloem of the stolons.It is concluded that in the initial phase of tuber growth, mainlyfactors outside of the tuber determine its growth rate. In laterstages of tuber growth, when the sink strength increases, thecompeting strength of individual tubers for photosynthate isdominated mainly by factors within the tuber itself, such astheir sink size and sink activity. Key words: Potato tuber, sink size, tuber initiation, transport resistance  相似文献   

7.
In potato plants fast and slow growing tubers develop on thesame plant. A hypothetical causality between tuber growth rateand tuber cell number was investigated by determining the tubercell number with the aid of an automatic counting procedure.Our data show a close correlation between tuber size and cellnumber over the whole range of tuber volumes considered (3–28cm3). If the influence of tuber size on cell number is eliminatedby means of a partial correlation analysis, the cell numberof the entire tuber is not significantly correlated with itsgrowth rate. An exclusive consideration of the smaller cells(10–30 µm) in the apical tuber region, where thecell division rate in potato tubers is highest, reveals a loosebut significant partial correlation to tuber growth rate (r= 0.383, P < 0.05). The growth rate of the slow growing tubers of any potato plantmay be enhanced by removing the fast growing tubers. In thefirst few days this enhanced growth rate is not due to a stimulationof cell division rate, but rather due to cell expansion. Potato, Solanum tuberosum L., tuber growth rate, tuber cell number  相似文献   

8.
Regulation of potato tuber protein accumulation by gibberellic Acid   总被引:2,自引:0,他引:2  
Many studies have shown that gibberellic acid (GA3) inhibits tuberization in potato (Solanum tuberosum L.). In this study, we have utilized the 40 kilodalton glycoprotein, patatin, as a marker for biochemical events associated with the process of tuberization. To determine the effects of exogenous applications of GA3 on the induction of the accumulation of this major tuber protein, we measured patatin levels in tubers from treated whole plants, petioles from a single-node cutting system with GA3 applied in a lanolin paste, and stolon tips cultured in vitro on an inductive medium supplemented with GA3. In all three systems, GA3 inhibited the accumulation of patatin and the major 15 and 22 kilodalton tuber proteins. This effect appeared to be selective since most of the other proteins were not affected and, in tubers, at least one protein was stimulated by GA3. These results suggest that GA3 can reverse biochemical events of tuberization in tubers as well as prevent the accumulation of the major tuber proteins in other inducible tissues.  相似文献   

9.
Potato plants (Solanum tuberosum L.) were grown in water culturein a controlled environment. The growth rates of individualtubers were closely reflected by their 14C-content 20 h after14CO2 had been applied to the aerial parts of the shoot for4 h. The 14C-content of the tuber (sink strength) was significantlycorrelated to the 14C-concentration of the tuber tissue (14Cg–1 fr. wt.=sink activity). The sink activity, which differedbetween individual tubers by up to a factor of 10, was alsoclosely related to the conversion rates of 14C into the starchand the remainder as well as to the 14C-content in the ethanolsoluble fraction. This indicates the simultaneous use of photosynthatefor growth and storage in the growing tubers. No preferenceof photosynthate utilization for either of these processes couldbe detected in relation to the sink activity of the tubers.Tubers with high sink activity imported 14C-labelled photosynthateat higher rates although their tissue contained higher concentrationsof reducing sugars and sucrose than the tissue of tubers withlow sink activity. Despite the close relationship between sinkactivity and the rate of starch synthesis (14C-conversion intostarch), no significant correlation was found between sink activityand the actual starch concentration of the tissue. The applicationof zeatin riboside directly onto individual tubers increasedtheir growth rates in comparison to non-treated tubers of thesame plant. The results indicate the importance of both growthand storage processes for the regulation of sink activity inyoung potato tubers. Key words: Potato tuber, 14C-photosynthate partitioning, zeatin riboside application  相似文献   

10.
Potato plants (Solanum tuberosum L.) were grown in water culturein a controlled environment. Cooling (+8°C) of individualtubers decreased their growth rates and increased the growthrates of non-cooled tubers of the same plant. The carbohydrateconcentration in non-cooled and cooled tubers did not differsignificantly, but 14C-import from labelled photosynthate waslower in cooled than in non-cooled tubers. The markedly lowerconversion rate of ethanol-soluble 14C to starch in cooled,in comparison to non-cooled tubers, was not associated withsignificant differences in the in vitro activities of starchsynthase, ADPG-pyrophosphorylase and starch phosphorylase understandard assay conditions (+30°C). However, the Q10-valuesof the enzymes differed in vitro in the temperature range between30°C and 8°C, leading to a marked decrease in the activityratio of ADPG-pyrophosphorylase/starch phosphorylase in cooledtubers. In tubers differing in growth rates without manipulation, 14d after tuber initiation significant positive correlations werefound between 14C-concentration of tuber tissue and the in vitroactivities of starch synthase and ADPG-pyrophosphorylase anda significant negative correlation between 14C-concentrationand starch phosphorylase. In contrast, in tubers which wereanalysed 5 d after initiation, there were only small differencesbetween tubers in growth rate, 14C import and the activity ratioADPG-pyrophosphorylase/starch phosphorylase. From various directand indirect evidence it is concluded that the growth rate ofindividual tubers, and thus the sink strength, is at least inpart controlled by the activity of starch synthesizing enzymes. Key words: Potato tuber, cooling, starch synthesizing enzymes  相似文献   

11.
Gibberellins GA1, GA4, GA8, GA9, GA19, GA20, GA29, GA44, GA81,indole-3-acetic acid (IAA) and abscisic acid (ABA) were identifiedin cambial region tissues of Eucalyptus globulus by comparingmass spectra and Kovats retention indices with those of authenticstandards. Using stable isotope labelled internal standardsGA19, GA20 and GA44 were quantified at levels of 2–7 ng(g fr wt)-1, other GAs were present at levels < 1 ng (g frwt)-1. Levels of IAA and ABA ranged from 417–1, 140 ng(g fr wt)-1 and 86–305 ng (g fr wt)-1 respectively. Thepresence of brassinosteroid-like substances was also indicatedbased on activity in the rice seedling leaf inclination assay. (Received April 28, 1995; Accepted June 20, 1995)  相似文献   

12.
In Pisum sativum L. a third, more severe, allele at the internodelength locus le is identified and named led. Plants homozygousfor led possess shorter internodes and appear relatively lessresponsive to GA20 than comparable le (dwarf) plants. Gene ledmay act by reducing the 3ß-hydroxylation of GA20 tothe highly active GA1 more effectively than does gene le. Theresults indicate that le is a leaky mutant and therefore thatendogenous GA1 influences internode elongation in dwarf (le)plants. Pisum sativum, peas, internode length, genetics, gibberellin, dwarf elongation  相似文献   

13.
OPARKA  K. J. 《Annals of botany》1985,55(5):705-713
Potato plants were labelled with 14CO2 at six stages duringtuber bulking and changes in current assimilate partitioning(20 h after 14CO2 assimilation) were examined in relation toincreasing tuber size on a plant. There was no relationshipbetween the node of origin of a tuber and the amount of 14Cwhich entered it, and those tubers on a plant which importedthe most 14C did not all belong to the same stem. However, competitionwithin a node was evident as many tubers borne on second-orderstolons were smaller and contained significantly lower concentrationsof 14C than those on primary stolons. Two weeks after tuberinitiation there was an almost linear relationship between thefresh weights of the tubers and their 14C content but the correlationbecame less good at subsequent harvests. Within the tubers theratio of 14C starch: soluble fell over the course of the experimentand was reflected in an increase in the percentage of 14C sucroseappearing in the tubers at each harvest. At any one harvest,however, the 14C starch: soluble ratios were similar but notrelated to the rates of 14C import of the tubers. The data areconsistent with the view that sucrose is compartmentalized inpotato tubers. Assimilate, 14Carbon, potato, sugars, tuber  相似文献   

14.
The permeability to oxygen of the periderm of the potato tuberhas been measured during its development and storage. When expressedas ml O2, diffusing through 1 cm2 periderm in 1 sec under anO2, pressure of 1 atm, the values for freshly harvested tubersranged from a maximum of 2.4 x 10–4 in immature tubers,to less than 0.7 x 10–4 in tubers harvested mature someweeks after the death of the foliage. In every case, after storagefor up to 10 weeks at 10° C, the permeabilities, as expressedabove, were less than 0.7 x 10–4 (minimum values, c. 0.5x 10–4 It was shown that the oxygen deficit under theperiderm was unlikely to exceed 0.03 atm during development,and the oxygen status of the developing tuber should thus beadequate for the low oxygen-affinity oxidase system (if present)to function.  相似文献   

15.
Following stratification seeds of Corylus avellana exhibitedtheir characteristic ability to germinate at 20 °C undermoist conditions. Stratification of the intact fruit also stimulatedelongation of the cotyledonary petiole when isolated cotyledonswere transferred to moist conditions at 20 °C. GA3 inducedboth of these effects in non-stratified material. ABA substantiallydecreased seed germination and the response of cotyledonarypetioles to stratification and GA3. CCC2 applied to stratifiedor GA3-pretreated cotyledons did not depress the final percentageof growing petioles. Cotyledons can clearly regulate the development of their petiolesin the absence of the embryonic axis. It is concluded that thereis at least one gibberellin-sensitive site in the cotyledonscapable of initiating petiole development independent of axiscontrol.  相似文献   

16.
Reducing sugar levels in potato tubers increased up to eight-foldduring storage from October to May, with almost all the riseoccurring after emergence from dormancy in December. Removalof all buds from the tubers within a month of harvest preventedthis rise in soluble carbohydrate, but application of a lanolinpreparation of gibberellic acid (GA3 to the ‘eye’-positions completely substituted for the buds in permittingthe same pattern and magnitude of sugar formation in the storagetissues. Discs of tuber tissue responded to exogenous GA3 byforming reducing sugars only when obtained from non-dormanttubers. It is con cluded that both the buds and the storagetissues exhibit dormancy, and that breaking of this during after-ripeningoperates independently in the two regions, with the storagetissues becoming responsive to bud-synthesized gibberellin onlyafter they have themselves emerged from the dormant condition. Levels of activity of starch phosphorylase, amylase and acidphosphatase in the storage tissues rose markedly after emergencefrom dormancy, but neither disbudding nor exogenous gibberellinhad any quantitative or qualitative effect on these enzymes.Thus, it appears that neither enzyme synthesis nor enzyme activationwas stimulated by gibberellin, and it is suggested that gibberellinregulation of the mobilization of the reserve materials is achieved,at least initially, through effects on cell compartmentation.  相似文献   

17.
Inhibition of the biosynthesis of gibberellins by prohexadione,3,5-dioxo-4-propionylcyclo-hexanecarboxylic acid, was studiedwith cell-free systems derived from immature seeds of Cucur-bitamaxima, Phaseolus vulgaris and Pisum sativum. Prohexadione,at a concentration of 10–4 M, inhibited C-7 oxidationof GA12-aldehyde, C-20 oxidation of GA15, conversion of C20-gib-berellinsto C19-gibberellins, 3ß-hydroxylation, 2,3-dehydrogenationof GA20, 2,3-epoxidation of GA5 and 2ß-hydroxylationof GA9 and GA20. The 3ß-hydroxylase activity appearedto be more sensitive to prohexadione than were the C-20 oxygenaseand the 2ß-hydroxylase activities. The conversionof mevalonic acid to GA12-aldehyde and the 13-hydroxylationof GA12 were not affected by prohexadione at a concentrationof 3 ? 10–4 M. All of the steps inhibited by prohexadioneare oxidation steps catalyzed by soluble enzymes that require2-oxoglutarate, Fe2+ and oxygen, and all of them occur distalto the synthesis of GA12-aldehyde in the biosynthesis of gibberellins. (Received April 4, 1990; Accepted September 14, 1990)  相似文献   

18.
Four kinds of GA, GA1, GA2, GA3, and GA4, all inhibited sproutingin aerial tubers of Begonia evansiana. The sprout-inhibiting action of GA increased with incubationin a high O2 concentration, and decreased in a low O2 Concentration. Inhibition of sprouting by GA was reduced by incubation in thepresence of p-nitrophenol, resorcinol, salicylaldoxime, 2, 4-dinitrophenol,sodium azide and cycloheximide. The higher activity of polyphenol oxydase was observed in ahomogenate of GA treated tubers. Existence of counteracting two systems which were activatedby GA was considered. (Received January 13, 1972; )  相似文献   

19.
The metabolism of GA12 and its precursors was investigated incultured cells of seven cell lines of Nicotiana tabacum andthree cell lines of Catharanthus roseus using l4C-labeled substrates.The presence of a metabolic pathway from ent-7-hydroxykaurenoicacid to GA53 via GA12-aldehyde and GA12 was demonstrated inthe cultured cells. GA12 was effectively converted to GA53 incells of BY-2, 2b-4, 2b-13 and CG from N. tabacum. By contrast,GA53 was not converted to any other GAs in all of the linesof cells examined. The metabolism of C19-GAs was also examinedusing 3H-labeled substrates. The conversion of GA20 to GA29and GA, and of GA4 to GA34 occurred more efficiently in cellsfrom C. roseus than in cells from N. tabacum. However, 13-hydroxylationof GA4 and GA9 was not observed in any of the cell culturesexamined. Among the various metabolites, GA53, GA29 and GA34were identified by full-scan GC/MS. (Received December 20, 1990; Accepted May 27, 1991)  相似文献   

20.
The dependence of membrane potentials on changes in the extra-cellularK+ concentration [K+]e was investigated in potato tuber sliceswith dripping perfusion, and in growing Vigna hypocotyl segmentswith pressurized intra-organ perfusion methods. Only under anoxiawere the membrane potential of potato tuber slices and the electricpotential difference between the parenchyma symplast and xylem(Vpx) of Vigna hypocotyl segments depolarized markedly (46 mVand 42 mV/log[K+]e unit, respectively) with increasing [K+]eabove the critical values. The electric potential differencebetween the parenchyma symplast and organ surface (Vps of thehypocotyl segments remained nearly unchanged up to 30 mEq [K+]e.Under highly aerobic conditions the membrane potentials wererelatively independent of [K+]e except at very high K+ concentrations.Vps showed even hyperpolarization with the increasing KCl concentrationin the perfusion solution that is not in direct contact withthe surface membrane of the parenchyma symplast. The respiration-dependentelectrogenic components of the membrane potentials regularlyincreased with the increasing [K+]e. A voltage-dependent homeostaticcontrol of membrane potential is discussed. (Received August 13, 1984; Accepted December 21, 1984)  相似文献   

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