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1.
Basal applications of plant growth regulators to excised rootsof Ophioglossum induce modifications in the outer cortical cells.Benzyladenine initiates periclinal divisions in these outercells producing a periderm-like tissue while 2,4-Dcauses cell enlargement only. Walls of the outer cells of theperiderm-like tissue are resistant to sulphuricacid and stain with Sudan IV and presumably are suberized. 相似文献
2.
Diurnal laminar reorientation was followed in solar-trackingleaves of Lavatera cretica L. under simulated conditions. Asimulated sun was moved over the lamina in a 180?arc in the vertical plane of the mid-vein, at an angular velocityof 15? h1 in a regime of 12-h photoperiods. In one groupof plants the petioles of the experimental leaves were arrangedto face sunrise, while in the other they werearranged to face sunset. At sunrise,the laminae in both groups, which were inclined towards theanticipated direction of sunrise, changed theirelevation towards the rising sun, resulting inprogressive reduction in the angle of incidence (AI) of lighton the laminar surface (AI= differential between laminar andsolar elevation). As a result, laminar and solarelevation converged, and laminar reorientation gradually ceased,until the solar elevation had passed the normalto the laminar surface (AI=0?). laminar reorientation was thenresumed, but its direction was reversed to follow the directionof solar reorientation. During most of the remainingday, laminar elevation (LE) trailed that of thesun by an average of 11?-14?. Laminar reorientationthen anticipated sunset by starting to slow down60 to 90min in advance. During the 12-h dark period, the laminareoriented towards the anticipated direction of the subsequentsunrise. The time-course of nocturnal reorientationwas qualitatively different in the two groups of experimentalplants. The time-course of diurnal phototropism under naturaland simulated conditions is analysed and compared and differencesand similarities between them are discussed. Key words: Diurnal phototropism, solar-tracking, vectorial excitation 相似文献
3.
Impedance spectroscopy was used in studying frost hardinessof leaves of two diploid rhododendron cultivars, RhododendronL. PJM and R. Cunningham's White,and their tetraploid derivatives, R. Northern Starburst(NSB) and CW4. After the growing season and initial hardeningin a greenhouse, plants were subjected to an acclimation regimein a phytotron: 3 consecutive weeks at +5, +1 and -2°C each.Hardiness was studied with controlled freezing tests beforeeach decrease in temperature and at the end of the experiment,based on data of extracellular resistance reand relaxation time of the frost-exposed leaves. The correlation of the two estimateswas 0.92. Generally, the diploid clones had better frost hardinessthan the tetraploid clones. At the end of the experiment, frosthardiness of the diploid PJM was -28.7°C andthat of the tetraploid NSB -20.6°C. Leaves of the diploidCunningham's White and of the tetraploid CW4 hardenedto -32.0°C and -20.9°C, respectively. Frost hardinessestimated by impedance spectroscopy correlated well with earlierresults based on visual scoring (r = 0.810.86) and electrolyteleakage tests (r = 0.840.90), but results from impedancespectroscopy indicated weaker hardiness than the other tests.The difference between the results from impedance spectroscopyand the other tests was smaller and more coherent within theCunningham's White clones than within PJMand NSB. Changes in extracellular and intracellular resistanceof non-frozen leaves during the acclimation correlated withthe changes in frost hardiness of Cunningham's Whiteclones, but not with those of PJM and NSB, whichbelong to another subspecies.Copyright 2000 Annals of BotanyCompany Cold resistance, evergreen, frost hardiness, impedance spectroscopy, polyploid, Rhododendron, tetraploid 相似文献
4.
ROMERO-ARANDA R.; BONDADA B. R.; SYVERTSEN J. P.; GROSSER J. W. 《Annals of botany》1997,79(2):153-160
The effect of tetraploidy on leaf characteristics and net gasexchange was studied in diploid (2x ) and autotetraploid (4x) Valencia sweet orange (Citrus sinensis (L.)Osb.) and Femminello lemon (Citrus limon (L.)Burm. f.) leaves. Comparisons between ploidy levels were madeunder high irradiance (I) in a growth chamber or low total Iin a glasshouse. Tetraploids of both species had thicker leaves,larger mesophyll cell volume and lower light transmittance thandiploids regardless of growth I. Mesophyll surface area perunit leaf area of 2x leaves was 515% greater than on4x leaves. Leaf thickness and mesophyll cell volume were greaterin high I leaves than low I leaves. In high I, average leafarea was similar for 2x and 4x leaves, whereas in low I it was30% greater in 4x than in 2x leaves. Nitrogen and chlorophyllconcentration per cell increased with ploidy level in both growthconditions. The ratio of chlorophyll a:b was 25% greater in2x than in 4x leaves. When net CO2assimilation rate (ACO2) wasbased on leaf area, 4x orange leaves had 2435% lowerACO2than their diploids. There were no significant differencesin ACO2between 2x and 4x orange or lemon leaves when expressedon a per cell basis. Overall, lower ACO2per unit leaf area oftetraploids was related to increase in leaf thickness, largermesophyll cell volume, the decrease in mesophyll area exposedto internal air spaces, and the lower ratio between cell surfaceto cell volume. Such changes probably increased the resistanceto CO2diffusion to the site of carboyxlation in the chloroplasts. Cell volume; chlorophyll; irradiance; leaf thickness; nitrogen; photosynthesis; ploidy; Citrus limon ; C. sinensis ; Valencia sweet orange; Femminello lemon 相似文献
5.
KANAMORI-FUKUDA IKUKO; ASHIHARA HIROSHI; KOMAMINE ATSUSHI 《Journal of experimental botany》1981,32(1):69-78
Marked changes in the activity of the de novoand salvage pathways of pyrimidine biosynthesisduring growth of Vinca rosea cells in a batch suspension culturewere observed. The activity of these pathways was investigated by determiningthe contribution of 14C of [2-14Cluracil, 12-14Cluridine. and[6-14Clorotate to the cell constituents and by measuring theactivity of the several enzymes of these pathways. During the lag phase of the culture, uracil- anduridine-salvage pathways made the predominantcontribution to nucleotide biosynthesis, but, following theinitiation of cell division, the de novo pathwayfor nucleotide biosynthesis operated appreciably. These results suggest that nucleotide synthesis during cellgrowth in a suspension culture can be divided into two stages:a turnover stage, during the lag phase of cellgrowth, and a true biosynthetic stage, which isinitiated in the cell division phase. 相似文献
6.
Crop phenology is one of the most important characters influencingproductivity in a given environment. Narrow-leafed lupin (Lupinusangustifolius L.) is a major grain legume crop in southern Australiawith general phenological adaptation to this Mediterranean-typeenvironment. However, it is an indeterminate crop with severalassociated limitations to productivity, such as overlappingvegetative and reproductive growth, late grain filling and sometimesexcessive vegetative growth. Here we studied two novel typesof narrow-leafed lupin with restricted branching, which mightbe useful for overcoming these problems. These restricted branchinglupins arose spontaneously within a breeding population, inthe case of Tallerack, and within a farmer's cropin the case of Hurst and we compared them withthe Merrit, which is widely grown and has thenormal indeterminate branching habit. The morphology and developmentof the main shoot of these genotypes were similar. However,Hurst had much larger leaves. There were alsostriking differences in the lateral branches of the restrictedbranching types; they had fewer leaves than Merritand flowered earlier. These differences were most marked in Hurst, where the upper main stem branches werereduced to a single floret in the axil of main stem leaves,and these flowers often exhibited abnormal morphology. Copyright2000 Annals of Botany Company Lupinus angustifolius L., narrow-leafed lupin, adaptation, development, morphology, branching, leaves, mutant, plastochron, phyllochron, floral initiation, flowering. 相似文献
7.
A Cytochrome P450 Mediated Naringenin 3'-Hydroxylase from Sweet Orange Cell Cultures 总被引:1,自引:0,他引:1
Doostdar Hamed; Shapiro Jeffrey P.; Niedz Randall; Burke M.D.; McCollum T. Gregory; McDonald Roy E.; Mayer Richard T. 《Plant & cell physiology》1995,36(1):69-77
A microsomal flavonoid 3'-hydroxylase (F3'H) catalyzing themetabolism of naringenin to eriodictyol in Citrus sinensis (L.)Osbeck cv. Hamlin cell suspension cultures wasshown to be a cytochrome P450 enzyme. This reaction requiredO2 and NADPH and was inhibited by CO, with partial reversalof CO-inhibition by light at 450 nm. Cytochrome P450 contentranged from 1020 pmol (mg microsomal protein)1.The F3'H reaction was shown to be linear in regard to proteinconcentration between 2.5 and 25 µg of microsomal protein.The optimum pH for the reaction was 7.47.6 and the temperatureoptimum was between 30 and 37°C. The apparent Km and Vmaxfor naringenin were 24 µM±3.2 and 81.4±7.9pmol eriodictyol min1 (mg protein)1, respectively.The microsomal F3'H was also capable of forming dihydroquercetinfrom dihydrokaempferol (40 pmol min1 (mg protein)1)and of quercetin from kaempferol (3.25 pmol min1 (mgprotein1). Cytochrome c and ketoconazole were the bestinhibitors of WH activity followed by piperonyl butoxide anda-naphthoflavone. Light was shown to be an inducer of the F3'Halmost doubling the specific activity and increasing the microsomalcytochrome P450 content by 30% over that of dark grown cells.F3'H activity was also confirmed in microsomal preparationsof young (new flush) leaves from Hamlin treesand flavedo of Hamlin oranges, Marshgrapefruit, and Lisbon lemon. No activity wasobserved in older, hardened leaves and albedo of all the fruittested. Initiation of embryogenesis in the Hamlincell suspension cultures by switching from a sucrose mediumto a glycerol-based medium resulted in the down-regulation ofF3'H.
1Mention of a trademark, warranty, proprietary product, or vendordoes not constitute a guarantee by the U.S. Department of Agricultureand does not imply its approval to the exclusion of other productsor vendors that may also be suitable. 相似文献
8.
The postulated mechanical advantage of subsidiary cells overguard cells has been estimated using leaves of Tradescantiavirginiana. The turgor pressures of subsidiary cells were adjusted to bezero or maximal by plasmolytic treatments, and the resultingstomatal apertures were measured. The mechanical advantagewas calculated from two mathematical models which define itas an antagonism ratio. The discussion deals withmethods of preparing the tissue, the validity of the plasmolytictreatments, and the function of the antagonism ratio in relationto the Spannungsphase 相似文献
9.
This review compares new developmental models on flowering andother vascular plants with evolutionary hypotheses formulatedby Agnes Arber (18791960) and like-minded botanists.Special emphasis is laid on philosophical basics such as perspectivism,pluralism about evolutionary modelling, continuum way of thinking,and fuzzy logic. Arber's perspective is best labelled as F uzzyA rberian M orphology (FAM Approach). Its proponents (FAMmers)treat structural categories (e.g. roots, shoots,stems, leaves, stipules)in vascular plants as concepts with fuzzy borderlines allowingintermediates (including transitional forms, developmental mosaics).The FAM Approach complements Cla ssical Plant M orphology (ClaMApproach), which is the traditional approach in botany. ClaMproponents (ClaMmers) postulate that the structuralcategories of vascular plants are regarded as concepts withclear-cut borderlines and without intermediates. However, duringthe evolution of vascular plants, the root-shoot distinctionand the stem-leaf distinction have become blurred several timesdue to developmental changes, resulting in organs with uniquecombinations of features. This happened, for example, in thebladderworts (Utricularia, Lentibulariaceae). When focusingon the leaf, the FAM Approach is identical toArber's partial-shoot theory of the leaf and Sinha'sleaf shoot continuum model. A compound leaf canrepeat the developmental pathway of the whole shoot, at leastto some degree. For example, compound leaves of Chisocheton(Meliaceae)with indeterminate apical growth and three-dimensional branchingmay be seen as developmental mosaics sharing some growth processeswith whole shoots! We focus here on the FAM Approach becausethis perspective is especially promising for developmental geneticistsstudying flowering and other vascular plants. Copyright 2001Annals of Botany Company Review, body plan, developmental mosaics, leaf development, history of botany, homeosis, homeotic genes, Lentibulariaceae, morphological evolution, process morphology, stipules, Utricularia, flowering plants 相似文献
10.
When a dicotyledonous stem is wounded by longitudinally splittinga young internode into halves, cells near the cut surface proliferateto form a callus within which vascular tissues differentiateand tend to restore a vascular cylinder in each half. Threephases of regeneration after wounding were identified and quantifiedin stems of three Solanaceous species. (1) In an initial lagphase, lasting about 2 d, neither cell division nor enlargementwere detected, but mitotic figures were observed within about300 µm of the cut surface. (2) Throughout a second, divisionphase, from about days 210, cell division and enlargementoccurred. Both were initiated mainly in the two cell layersnearest the surface. A mass of callus formed, with new cellwalls mostly parallel to the surface. Cell enlargement laggedbehind cell division for the first few days, so that mean radialcell diameter decreased until day 6, thereafter remaining almostconstant at 3040 µm. Towards the end of this phase,mitoses ceased within the callus except in the positions ofthe future vascular and cork cambia, where radial cell diameterfell towards a constant 1520 µm. (3) During a third,differentiation phase, cell division was restrictedto the cambial zones, and derivatives differentiated into cork,phloem or xylem according to position. The rate of increasein cell number per transect was 1.52.0 cells d1,of which more than half was xylem. Capsicum annuum L., sweet pepper, Lycopersicon esculentum Mill., tomato, cambium, cell division, differentiation, regeneration, wounding of stems, xylem 相似文献
11.
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
12.
Regular rows (scala) of pectic strands of uniformthickness interconnect palisade cells of leaves of a wide rangeof plant species, the leaf lamina of which possesses a regularpalisade layer. As the strands can be viewed by scanning electronmicroscopy of fractured, uncoated, fresh frozen leaves, theyare not artefacts. The techniques of electron probe analysis have been used toexamine fresh frozen leaves of holly in which there are regularpectic scala. Evidence is presented to support the view alreadyput forward, to explain the origin of the strands, that theyare deficient in calcium. The strands are shown to be rich inpotassium which, like the potassium in leaf cells, can be readilyleached with water. The advantages of fresh frozen plant material for elementalelectron probe analyses as well as problems arising from surfaceirregularities and surface charging, are discussed. pectic strands, leaf palisade parenchyma, electron-probe micro analysis, calcium, potassium 相似文献
13.
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
14.
Cordeauxia edulis (Somalia and Ethiopia), andStuhlmannia moavii(Tanzania, Kenya and Madagascar) are evergreen shrubs or smalltrees of dry areas. They have similar leaf anatomy as revealedby resin sectioning and scanning electron microscopy. The cuticleis extremely thick and all vascular bundles lack bundle sheathextensions. The most unusual feature is the mesophyll, threeto seven layers consisting entirely of cylindrical palisadecells with lateral walls capable of changing vertical lengthby folding in a concertina-like manner. The matching outwardfolds of two adjacent cells always remain attached by meansof a row of wall thickenings (pegs). The pegscan elongate, especially so between the widely separated mesophyllcells that occupy the substomatal chamber area. The unattachedflexible inward wall folds enable these concertinacells to shorten or lengthen vertically without disrupting cellinterconnections in the interior of each relatively long-livedleaf as it periodically loses and gains water. Concertina cellsmay be an anatomical adaptation allowing these leaves to remainevergreen and survive extended periods of drought and yet tostore water quickly when it becomes available. Leguminosae; Caesalpinioideae; Cordeauxia ; Stuhlmannia ; concertina mesophyll cells; desert adaptation; hollow glandular trichomes; leaf anatomy; wall thickenings 相似文献
15.
The metabolic fate of [U-14C]sucrose in suspension culturesof Catharanthus roseus cells was monitored for 96 h after thecells were transferred to fresh complete (+Pi)or to phosphate-deficient Murashige and Skoog (Pi)medium. Sucrose was hydrolysed extracellularly to glucose andfructose. The rate of uptake of sugars by the cells was 1.53times higher in +Pi culture than in Piculture. Little difference in the rate of incorporation of radioactivityinto the ethanol-soluble fraction was found between the +Piand Pi cultures during the initial 24h of culture, but after 48 h the rate in +Picultures was higher than that in Pi cultures.Incorporation of radioactivity into ethanol-insoluble macromoleculeswas always significantly higher in the cells in +Picultures than in those in Pi cultures.The results suggest that Pi strongly affects the utilizationof sugars by cultured plant cells through the stimulation oftransport of sugars as well as through the activation of metabolism. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, sucrose, transport, metabolism 相似文献
16.
Megasporogenesis in Taxus led to a T-shaped tetrad, the mitochondriaand plastids being largely confined to the chalazal megaspore,the only spore to show further development. Germination of themegaspore followed very soon after its formation. The femalegametophyte was initially coenocytic but after about one monthit became cellular, new walls arising between the nuclei inpositions marked out by accumulations of cisternae of endoplasmicreticulum. No secondary spindles or other formsof microtubular participation in the siting of these walls couldbe detected. The development of the archegonia could not be resolved withcertainty, but it seemed likely that the cell analogous to thecentral cell of the pteridophyte archegonium eventually becamethe egg cell. The cytoplasm of the egg cell was clearly zoned.Prominent in the outer cytoplasm were granular bodies, 25µm in diameter, identifiable with the grandes inclusionsdescribed from the egg cells of conifers. The evidence pointedto their being derived from hypertrophied plastids which hadencapsulated part of the cytoplasm, a view strengthened by thecomplete absence of recognizable plastids from the mature cell.Bundles of microtubules radiating from the nuclear envelopewere a conspicuous feature, possibly stabilizing the zonationof the cytoplasm. Megasporogenesis, Taxus baccata, egg cell, grandes inclusions 相似文献
17.
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
18.
Tomato plants were grown with limited or luxury water supplyand given nitrogen either as the ammonium ion or the nitrateion. The active iron fractions of the leaves asextracted by etherized tenth molar hydrochloric acid showedno relationship with the total iron but a very significant linearrelationship was found between the active iron fraction andthe ratio of total phosphorus to total iron. Recalculation of results presented by other investigators formaize plants grown in soil with various levels of moisture,phosphorus and iron also showed a highly significant linearrelationship between the active iron fraction and the ratioof total phosphorus to total iron. Lycopersicon esculentum L., tomato, active iron, phosphorus, Zea mays 相似文献
19.
One-node potato (Solanum tuberosum L. cv. Katahdin)cuttings were used to study early anatomical changes associatedwith tuberization. Starch deposition and the percentage frequencyof cells in mitosis increased in the medullary region of thebud within 1 d after cutting, whereas increases in average cellsize were not detected until 4 d after cutting. Starch depositionand mitosis were the earliest detectable changes in anatomyassociated with tuber initiation. Potato, Solanum tuberosum L., tuber initiation, cuttings, cell enlargement, mitosis, starch deposition 相似文献
20.
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