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1.
A column chromatographic technique, enabling identificationand quantitative estimation of fatty acids, has been employedto study fat metabolism in Citrullus during germination in thelight. This plant is characterized by an unusually rapid disappearanceof storage fat as the cotyledons expand and turn green. In spiteof the high catabolic activity there is no evidence for accumulationof free fatty acids or short-chain fatty acids at this stage.Information on this point derived from acid value or saponificationvalue of the oil is shown to be untrustworthy. Citrullus seed fat contains the following percentages of acids:linoleic 70·6, oleic 7·2, palmitic 10·1,stearic 11·2, and arachidic 0·6, and careful analysishas also revealed small amounts of octadecatrienoic acids, bothconjugated and non-conjugated. All the major acids are brokendown at rates proportionate to the quantities originally present,with the exception of oleic acid which is metabolized somewhatmore rapidly. Linolenic acid is synthesized in the expandinggreen cotyledons and the fatty acid composition of the latter,in the late germination stages, resembles that of a green leafand is very different from that of the seed. The results suggest a rapid removal of storage fat from thecotyledons and concomitant formation in small quantity of atypial leaf fat as the new photo-synthetic function develops. 相似文献
2.
After removal of the embryo from developing seeds of Vicia fabaL. and Pisum sativum L., the empty ovules werefilled with a standard solution (pH 5.5). Seed coat exudatesof both species were collected during relatively long experiments(up to about 12 h) and the concentration of sugar (mainly sucrose),amino acids and phosphate in the exudate measured. A discussionis presented on the amino acid/sugar ratio and the phosphate/sugarratio in the seed coat exudate. A pretreatment (15 min) withp-chloromercuribenzenesulphonic acid (PCMBS) reduced the releaseof sugar, amino acids and phosphate from broad bean seed coats.After excision of empty ovules of Vicia faba andPisum sativum from the maternal plant, 24 h after thistreatment a strong difference became visible between sucroserelease from excised seed coats and sucrose release from attachedseed coats. Similarly, when the rate of phloem transport ofsucrose into an empty ovule of Vicia faba or Pisumsativum was reduced by a sub-optimal mannitol concentrationin the solution, a reduced rate of sugar release from the seedcoat could be observed. Excision and treatment with a sub-optimalmannitol concentration reduced the release of amino acids toa lesser extent than for sucrose. These treatments did not reducethe rate of phosphate release from the seed coat. Key words: Seed development, Seed coat exudate, Phloem transport 相似文献
3.
The seed coat structure and histochemistry of Abelmoschus esculentuswere studied by bright-field, fluorescence and scanning electronmicroscopy. The seed coat was typical of species of the Malvaceae.The endotesta cells had inner tangential walls which were verythick and autofluorescent. The occurrence of phenolic substancesat this level has been related to seed coat imposed dormancy.The palisade cells were composed of three differently shapedparts: an upper prismatic part, a medium transitionpart and a lower twisted part. The formerwas rich in hydrophilic substances, the latter was lignified.The swelling of the prismatic parts was relatedto seed coat cracks. The region controlling onset of water entrywas thought to be the chalazal area. Thanks to the presenceof a large amount of highly acidic polysaccharide, water wasable to penetrate from the permeable maternal tissue, throughthe chalazal cap and plug as far as the boundary between thepalisade and underlying mesophyll. During imbibition of watera kidney-shaped blister was seen to rise, formedby separation of the palisade cells from an underlying singlelayer of subpalisade cells. The palisade layer forming the blisterroof showed the same histochemical characteristic of other seedregions. The single layer of the blister floor showed an affinitywith Toluidine Blue O and Alcian blue. Both blister roof andfloor were strongly autofluorescent. Abelmoschus esculentus (L.) Moench, okra, seed coat, chalazal region, water entry, structure, histochemistry 相似文献
4.
Histochemical investigations on the Prosopis juliflora seedcoat indicate the occurrence of a hydrophobic stripas the primary water barrier. Its position and the structureand histochemistry of the palisade cells of the seed coat differaccording to their location on the seed. These differences maybe responsible for differences in the water permeability ofvarious parts of the seed coat. In particular, parts of theseed coat in which the hydrophobic strip is locatedmore superficially tend to be more water impermeable than partslike the chalaza, in which the strip is more deeplylocated within the palisade cells. Prosopis juliflora, seed coat impermeability, palisade cells, hydrophobic strip 相似文献
5.
Dry legumes of Sesbania punicea (Cav.) Benth. contain impermeableseeds which are either beige-greenish or reddish. When keptin water for over one year they do not swell. Quick imbibitionwas induced by a deep cut, abrasion with coarse abrasive paper,immersion in concentrated sulphuric acid, in boiling water andin boiling KOH solutions. Neither lipid solvents (acetone, chloroform,cyclohexane, diethyl ether, ethanol, xylene), nor, at room temperature,KOH solutions up to 50% per cent, permeabilized the seeds. Astrong barrier to water entry appeared to be located in thepalisade layer which showed light points in places,and which seemed to be transversal thickenings. In the testa, callose, which may play a role in the impermeabilityof the Sesbania punicea seed, was detected. Sesbania punicea, germination, seed dormancy, seed coat impermeability, callose 相似文献
6.
The seeds of Cuscuta pedicellata have been investigated by transmissionand scanning electron microscopy. Additional observations havebeen made on seeds of C. campestris by SEM only. The seed coatconsists of an outer single epidermis, two different palisadelayers, and an inner multiparenchyma layer. The outer epidermalwall in C. pedicellata has a thick cuticle and zones rich inpectic substances. The thicker U-shaped cell wallsin the outer palisade layer are strengthened by a wall layerof hemicellulose. The inner palisade layer has thick walledcells with a light line. The inner cell wall ofthe compressed multiparenchyma layer has a thin cuticle. A fairlythick cuticle is positioned directly on the endosperm surface.The aleurone cell walls are different from the remaining endospermwalls. The latter are thick and believed to be of galactomannans.There is a clear zone between the plasmalemmaand the cell wall in the aleurone cells. The embryo cells arepacked with lipids and proteins. In Cuscuta campestris mostendosperm has been absorbed during the seed development. Theembryo apex has two minute leaf primordia. The features of theCuscuta seeds are discussed in relation to functional and environmentalconditions. Cuscuta pedicellata, Cuscuta campestris, seed, seed coat, cuticle, cell walls, endosperm, aleurone cells, galactomannan, embryo, TEM, SEM 相似文献
7.
After removal of the embryo from developing seeds of Pisum sativum,the empty ovules (seed coats without enclosedembryo) were filled with a solution (pH 5.5) containing mannitol(usually 400 mM) to which various salts were added. A solutioncontaining two isotopes ((a) [2H]-sucrose/[14C]aminoisobutyricacid (AIB) or (b) [3H]valine/[14C]asparagine mixture) was administeredto the plant via the petiole subtending the fruiting node, and[2H]solute and [14C]solute unloading from the seed coat wasmeasured, in pulse-labelling experiments of about 5 h. The presenceof 25 or 50 mM K+ in the empty ovule enhancedthe release of sucrose from the seed coat particularly duringthe first hours of the experiment, but the stimulating effectof K+ on the release of labelled solutes derived from aminoacids was much smaller. The presence of 25 mM CaCl2 did notaffect the release of sucrose or amino acids from the seed coat.The effect of K+ on sucrose and amino acid release is explainedas an inhibition of sucrose and amino acid resorption from theseed coat apoplast into seed coat cells, after unloading fromthe seed coat unloading sites. It is suggested that amino acidrelease is much less affected by K+ than sucrose release, becausefar less resorption of amino acids by seed coat parenchyma cellstakes place during amino acid transport into the seed coat cavity. Pisum sativum, pea, assimilate transport, assimilate unloading, seed-coat exudate, seed development, sucrose resorption, surgical treatment 相似文献
8.
A study has been made of the changes during development in thetotal nitrogen, uncombined amino acid, starch and ethanol-solublesugar contents of field bean cotyledons from two large-seededcultivars, Minica and Felix, and two lines of the small-seededcultivar Dacre, which differed in protein concentration of themature seed. In all cultivars the concentration of total nitrogen,uncombined amino acids and ethanol-soluble sugars decreasedwhile that of starch increased during development. However,the pattern of decrease in the proportion of total nitrogenvaried between the large and the small-seeded cultivars. Fromday 40 (after pollination) onwards a higher percentage of ethanol-solublesugars but a lower percentage of starch was found in the large-seededcultivars. Throughout development the Dacre line with the highprotein concentration in the mature seed maintained a higherpercentage of total nitrogen and a correspondingly lower percentageof ethanol-soluble sugars and starch than the lowprotein line. Vicia faba L., field bean, nitrogen, starch, amino acids, sugars, protein 相似文献
9.
Investigations revealed that the anatomy of the primary radicularroot of yam bean (Pachyrhizus erosus L.) was typically dicotyledonousexcept that the xylem was not completely developed centripetally.Most of the roots had tetrarch xylem, although a few triarchand pentarch roots were also observed. In both tuberous andnon-tuberous roots, secondary thickening occurred by the formationof the meristematic vascular cambium which formed secondarytissues in a normal fashion. Subsequently, tuberization wasinitiated in the secondary xylem by the development of anomaloussecondary cambia from parenchyma cells surroundingvessel elements. Anomalous secondary cambia alsodeveloped from parenchyma cells not associated with vessels.Subsequently, anomalous tertiary cambia differentiatedfrom tissues produced by the anomalous secondarycambia. Activities of these anomalous cambia resulted in theproduction of parenchyma storage cells and were chiefly responsiblefor the growth of the mature tuber. Pachyrhizus erosus L., yam bean, tuberous root, anatomy, anomalous secondary cambia, anomalous tertiary cambia, centripetal xylem development 相似文献
10.
Accumulation of fat in the oil-palm exocarp is delayed untilthe kernel has almost finished developing (at about 19 weeksafter pollination) and is then extremely rapid, a major partof the lipid being formed within a single week. Throughout theperiod studied (8 to 20 weeks after pollination) the fat-freedry weight remains approximately constant and carbohydrates(starch, sucrose, and reducing sugars) do not accumulate eitherprior to or during fat formation. Immature exocarps contain only a low proportion of fat (about1 per cent, of the dry weight) and this protoplasmiclipid has a different fatty acid composition (major componentspalmitic and linoleic acids accompanied by smaller amounts ofstearic and linolenic acids) from the later-formed oil (majorcomponents palmitic and oleic acids with smaller amounts ofstearic and linoleic acids). There is no evidence of fatty acidinterconversions at any stage of development. 相似文献
11.
Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of B extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of Bin lupin pods was 5001,500 times more potent than thatof inhibitor ß in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of A of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of B. Mature podsof virus-infected plants again yielded moreA,but also 2? times more B than pods of healthyplants. Healthy pods yielded more A than virus-infectedpods, and there was no difference in X. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. A accelerated abscission when applied proximally,and delayed or prevented it when applied distally. Bstrongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances A and B. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism. 相似文献
12.
Gibberellic-acid-like substances have been found in extractsfrom all parts of seedlings of tall and dwarf peas and in matureseeds of wheat, French bean and tall and dwarf peas. They werepresent in amounts equivalent to o103 µg-gibberellicacid in 100 plants (F.W. 100200 g.). Immature runnerbean seed yielded larger quantities, equivalent to 0.25 µg.gibberellic acid per gram fresh weight, distributed betweentestas, cotyledons, and embryos. 相似文献
13.
Effect of Cultivar, Temperature and Seed Size on the Germination and Emergence of Soya Beans (Glycine max (L.) Merr.) 总被引:2,自引:0,他引:2
The rapid and uniform establishment of soya bean [Glycine max(L.) Merr.] stands is conducive to higher yields. This studywas undertaken to determine the effects of cultivar, temperature,and seed size on the rate of germination and emergence. No cultivar effect on the germination rate was observed. However,in an emergence study from a sand-soil-peat mixture, cultivardifferences in emergence rates were noted(Chippewa 64> Wayne > Amsoy 71). In anotheremergence study (sand media) the cvs Calland andWilliams emerged faster than the cv. 'Wayne orWells. Time required for 50 per cent germination decreased (18.84.0days) as the temperature increased from 10 to 30 °C (5 °Cincrements). Emergence (50 per cent) from a sand-soil-peat mixturewas more rapid (19.86.3 days) as the simulated plantingdate (growth chamber set to simulate field temperatures) wasdelayed from 16 April to 15 June with an intermediate date of16 May. In addition, time required for 50 per cent emergence of thecultivars from sand decreased (79376 h) as the temperaturewas increased from 10 to 30 °C with no decrease from 30to 35 °C. Seed size effects were apparent, with the very small seed germinatingslower than the three larger seed sizes. In the emergence studieswith both the sand and sand-soil-peat mixture there was a generaltrend toward more rapid emergence with the smaller seeds. However,the absolute differences were small. Significant cultivar x temperature interactions were observedfor the germination and emergence rates. In most cases the cultivarsmerged in terms of germination and emergence rates at temperaturesbetween 10 and 20 °C and at the higher temperatures thecultivar rankings were different from those observed at temperaturesbelow the merging point. Glycine max (L.) Merr, soya bean, seed germination, establishment of seedlings 相似文献
14.
The layer of daytime concentration of Calanus ponticus (VC andVI C) performing daily vertical migrations and the layer ofwinter stock aggregation are confined to the depthof maximal gradient of the main pycnocline under an unusuallysharp oxycline. The concentration layer thickness ranges from2 to 2030 m and the Calanus concentration in it is >250ind. m3, sometimes being 3500 ind. m3 and evenmore. The population in the concentration layer is divided intotwo ecological groups: I, feeding and migrating specimens ofcopepodite stages V and VI, their body lipid contents being2560 µg min.1; and II, non-feeding and non-migratingspecimens of copepodite stage V, their body lipid contents being100150 µg ind.1. The relationship with oxygenconcentration was studied in both ecogroups. The experimentsshow that specimens of ecogroup II can exit at an oxygen concentrationof 0.06 ml 11, but at such concentration falling intoanabiosis. They die at 0.04 ml O2 11. Estimates of respirationof the group II specimens (winter stock) showthat lipids they store are sufficient for 7 months' survival.Depth of Calanus concentration is determined by water densityrather than concentration of oxygen. 相似文献
15.
The extent of post-phloem solute transport through the coatsymplasts of developing seeds of Vicia faba L. and Phaseolusvulgaris L. was evaluated. For Vicia seed coats, the membrane-impermeantfluorochrome, CF, moved radially from the chalazal vein to reachthe chlorenchyma and thin-walled parenchyma transfer cell layers.Thereafter, the fluorochrome moved laterally in these two celllayers around the entire circumference of the seed coat. Transferof CF from the chalazal vein was inhibited by plasmolysis ofattached empty seed coats. In contrast, the spreadof phloem imported CF was restricted to the ground parenchymaof Phaseolus seed coats. Fluorochrome loaded into the outermostground parenchyma cell layer was rendered immobile followingplasmolysis of excised seed-coat halves. Phloem-imported [14C]sucroseand the slowly membrane permeable sugar, L-[14C]glucose, werepartitioned identically between the vascular and non-vascularregions of intact Vicia seed coats. For 14C-photosynthates,these partitioning patterns in attached emptyVicia seed coats were unaffected by PCMBS, but inhibited byplasmolysis. Tissue autoradiographs of intact Phaseolus seedcoats demonstrated that a pulse of 14C-photosynthate moved fromthe veins to the grounds tissues. In excised Vicia seed coats,preloaded with 14C-photosynthates, the cellular distributionof residual 14C-label was unaffected by PCMBS. In contrast,PCMBS caused the 14C-photosynthate levels to be elevated inthe veins and ground parenchyma relative to the branch parenchymaof Phaseolusseed coat halves. Based on the above findings, itis concluded that the phloem of Vicia seed coats is interconnectedto two major symplastic domains; one comprises the chlorenchyma,the other the thin-walled parenchyma plus thin-walled parenchymatransfer cells. For Phaseolusseed coats, the phloem forms amajor symplastic domain with the ground parenchyma. Key words: Phaseolus vulgaris L, phloem unloading, photosynthate transport, seed coat, symplast, Vicia faba L 相似文献
16.
Effect of Source of Nitrogen on the Growth of Fiskeby Soya Bean: the Carbon Economy of Whole Plants 总被引:1,自引:0,他引:1
Fiskeby V soya bean was grown from seed germination to seedmaturation with two contrasting patterns of nitrogen metabolism:either wholly dependent on dinitrogen fixation, or with an abundantsupply of nitrate nitrogen, but lacking root nodules. The carbonand nitrogen economies of the plants were assessed at frequentintervals by measurements of photosynthesis, shoot and rootrespiration, and organic and inorganic nitrogen contents. Plantsfixing atmospheric nitrogen assimilated only 2530 percent as much nitrogen as equivalent plants given nitrate nitrogen:c. 40 per cent of the nitrogen of nitrate plantswas assimilated after dinitrogen fixation had ceased in nodulatedplants. The rates of photosynthesis and respiration of the shootsof soya bean were not markedly affected by source of nitrogen;in contrast, the roots of nodulated plants respiredtwice as rapidly during intense dinitrogen fixation as thoseof nitrate plants. The magnitude of this respiratoryburden was calculated to increase the daily whole-plant respiratory loss of assimilate by 1015 per cent over thatof plants receiving abundant nitrate. It is concluded that nodulatedplants grew more slowly than nitrate plants inthese experiments for at least two reasons: firstly, the symbioticassociation fixed insufficient nitrogen for optimum growth and,secondly, the assimila tion of the nitrogen which was fixedin the root nodules was more energy-demanding in terms of assimilatethan that of plants which assimilated nitrogen by reducing nitratein their leaves. 相似文献
17.
《Journal of experimental botany》1960,11(2):150
On page 235, Table I: Equation (1) for Node 4 should read A/Ac=0·840+0·0006Ac;Equation (2) for Node 4 should read A=0·89Acand Equation (2) for Node 510 should read A=0·813Ac. 相似文献
18.
During the growth of Isochrysis galbana, several non-proteinamines may be detected in the growth medium. Of these, one (termedTTl) accumulates in proportion to the numbersof cells present. The concentrations of TTl, andof another (termed TA), are 35 times higherin cultures in which Isochrysis is predated by Oxyrrhis marina.The lowest estimates of the concentration of extracellular TTlare an order of magnitude higher than those of any protein aminoacid. Of the protein amino acids, some like glycine are utilizedduring predation while others, like histidine, accumulate inthe medium Because of the unknown N-content and reactivity ofthe non-protein amines during HPLC, it is not possible to sayif these compounds (together with other components of dissolvedorganic N) form a significant proportion of the unaccountedfor N in the system after predatory activity. During predationin the absence of detectable free ammonium (when Isochrysismay be expected to be N-deprived), particles accumulate in themedium. Most of these are <2.5 µ.m in diameter andare suggested to be remains of digested prey. There is evidenceof a reassimilation of these particles by prey-deplete Oxyrrhis. 相似文献
19.
Mature seed coats of representatives of all three genera ofMusaceae were analysed for macromolecular composition with variousmass spectrometric techniques and compared with scanning electronmicroscopy and light microscopy in combination with histochemicaltechniques. Mass spectrometric techniques are more sensitiveand more specific in identifying macromolecular compounds thanhistochemical methods. The macromolecular fingerprintof the seed coats of Musaceae showed unique components of aromaticphenols. The seed coat structure of all three genera is homogeneouswithin the Musaceae. It is characteristic at the family leveland most complex within the Zingiberales. Very remarkable arethe separation of the outer cell walls from the exotestal layer,exposing a secondary surface with silica crystals, and the relativelythick mesotesta which protects the seed, e.g. against the bitingforces and passage through the digestive tracts of dispersingagents. Germination takes place with an operculum and is facilitatedby a predetermined rupture layer in the micropylar collar. Themusaceaous seed presents a good example of the solution of conflictingdemands of protection and germination. Musaceae; Musa; Ensete; Musella; seed coat; pyrolysis (gas chromatography) mass spectrometry; histochemistry; anatomy; macromolecules; silica; lignin; cellulose; vegetable polyphenols; operculum; germination 相似文献
20.
Growth analysis of plants raised under controlled environments(105, 12, 15, 18 and 20 °C, and 21 h photoperiod)was used to examine whether varietal differences in the minimumgermination temperature of four bean cultivars persist duringgrowth at suboptimal temperatures. A method to estimate theminimum vegetative growth temperature, based on axis relativegrowth rate, was developed. In order to compensate for ontogeneticdrift, the harvests were conducted at the same stage of developmentof the plants. Axis relative growth rates, reduction rates ofthe cotyledons and other growth parameters were calculated inorder to compare the cultivars. Cultivar Marschallshowed better growth potential at 12 °C than the others,Pergousa at 15 °C, and Marschall,Olsok and Pergousa at 18 and 20°C. The effect of temperature on axis RGR was similar forMarschall, Olsok and Pergousa(Q10 = 2·1) and more pronounced than for Processor(Q10 = 1·3). Although there were significant differencesin the growth parameters among the cultivars within each temperatureused, the differences did not correspond with the differencesduring germination at low temperatures. The minimum vegetativegrowth temperature was close to 10 °C for all the cultivarstested. Phaseolus vulgaris L., beans, suboptimum temperature, growth analysis, minimum germination temperature, minimum vegetative growth temperature 相似文献