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1.
Incorporation of polyamine-spermidine into the nutrient mediumat 106 and 105 M concentrations stimulates pollen-tubegrowth in vitro in Catharanthus roseus L. G. Don. MGBG, an inhibitorof spermidine biosynthesis, at 0.5 x 103 and 1 x 103M concentrations reduced the percentage of germination as wellas tube growth and at a concentration of 1.5 x 103 Mgermination was totally inhibited. Pollen grains incubated inthe medium containing 1.5 x 103 M MGBG, when transferredto a fresh medium with 105 M spermidine, resulted in80% germination recovery, along with considerable tube growth.Experiments with actinomycin-D indicate that stimulation ofpollen-tube growth by spermidine may involve de novo synthesisof protein. Catharanthus roseus, pollen germination, tube growth, spermidine, MGBG, inhibition, actinomycin-D 相似文献
2.
An interaction between aluminium (Al) and calcium (Ca) may bea cause of Al toxicity in plants. The pollen tube is a suitablesystem to test the interaction between Al and Ca since Ca ionsplay a pivotal role in pollen germination and tube growth. Weinvestigated how Al and other known blockers of Ca2+-permeablechannels (trivalent cations, ruthenium red, verapamil and nifedipine)influence pollen of an Australian native species Geraldton waxflower(Chamelaucium uncinatum). Pollen germination was inhibited bymicromolar concentrations of trivalent cations (La3+>Al3+>Gd3+)and ruthenium red, but it was relatively insensitive to a micromolarconcentration of verapamil. Exposure of the growing pollen tubesto micromolar concentrations of Al3+and La3+, and a millimolarconcentration of Ca2+chelator ethyleneglycol-bis(ß-aminoethylether)-N,N'-tetraacetic acid (EGTA) led to rapid tip bursting.In contrast, exposure to Gd3+, nifedipine, ruthenium red, verapamiland the organic trivalent cation tris (ethylenediamine)cobalt(TEC3+) caused only inhibition of pollen tube growth. The Al3+-relatedpollen tube bursting was reduced significantly by increasingeither solution pH from 4.5 to 6 or activity of Ca2+from 0.25to 5 m M. In contrast, La3+-related pollen tube bursting wasinsensitive to changes in Ca2+activity. The results are discussedin terms of Al interactions with cell wall Ca2+and the plasmamembrane Ca2+-permeable channels. Copyright 1999 Annals of BotanyCompany Aluminium toxicity, Ca2+-channel blockers, cell wall, Chamelaucium uncinatum, pollen germination, pollen tube growth. 相似文献
3.
Brassica oleracea pollen was applied to a basic medium of 1.5per cent agar and 15 per cent sucrose to which flavanoids wereadded at three concentrations. Two types of agar were used;with agar 1, quercetin at a concentration of 0.5 x 103per cent gave an increase in percentage germinating grains.With agar 2, an increase in germination occurred with kaempferoland naringin at concentrations of 0.5 x 103 and 0.5 x101 per cent respectively. Increase in pollen tube lengthoccurred with agar 2 and quercetin at a concentration of 0.5x 103 per cent. The stigma tissue of B. oleracea contains at least three andthe pollen at least one glycoside of quercetin. The sugars inthe glycosides were not identified. Pollen germination and pollentube extension were not stimulated exclusively by the flavanoidspresent in the stigma. The flavanoid composition of the stigmadid not vary amongst five different S-allele genotypes, indicatingthat flavanoids are probably not directly involved in the incompatibilityreaction of B. oleracea. 相似文献
4.
The Importance of Light Intensity for Pollen Tube Growth and Embryo Survival in Wheat x Maize Crosses 总被引:1,自引:0,他引:1
The success of Triticum aestivumxZea mays crosses, used to producewheat doubled haploids, is influenced by light intensity. Toexamine the basis for this response, pollen tube growth, embryosurvival and indicators of photosynthetic rate were measuredin two wheat cultivars (Karamu and Kotuku)crossed with maize at two irradiance levels (250 or 750 µmolm-2s-1, PAR). Pollen tube growth was significantly affectedby light intensity in Karamu plants but not inKotuku plants, despite both cultivars being pollinatedby the same maize source. The percentage of pollen tubes reachingthe cavity between the ovarian wall and integuments, or in themicropyle of Karamu plants at high light intensity(65%) was nearly three-times greater than that at low lightintensity (22%). Thus, either low light intensity can affectthe maternal wheat plant in a way that inhibits pollen tubegrowth and/or high light intensity may promote pollen tube growthin Karamu plants. Significant differences in ratesof electron transport in plants grown at the two light intensitiesindicated that the rate of photosynthesis may also have an effecton pollen tube growth. These results have importance for improvingthe efficiency of wheat x maize crosses and other wide cerealcrosses. Copyright 2001 Annals of Botany Company Intergeneric hybridization, light intensity, pollen tube growth, embryo survival, Triticum aestivum, wheat,Zea mays , maize 相似文献
5.
Irradiation of spores of the fern Mohria caffrorum Sw. witheither red light (67.4 µW cm2) or far-red light(63.2 µW cm2) for a period of 24 h induced maximumlevels of germination. Brief irradiations with blue light (127.6µW cm2) administered before or after photoinductioncompletely nullified the effects of red or far-red light; however,with prolonged exposure to blue light, germination levels roseto near maximum. The similar effects of red and far-red lightin promoting spore germination makes the involvement of phytochromein this process questionable. Based on energy requirements,the promotive and inhibitory phases of blue light appear toinvolve independent modes of action. Mohria caffrorum, ferns, spore germination, photoinduction, phytochrome 相似文献
6.
Effect of Salt Stress on Viability, Germination and Endogenous Levels of Some Metabolites and Ions in Maize (Zea mays L.) Pollen 总被引:2,自引:0,他引:2
Maize plants, subjected to 0, 80, 120 and 160 meq l1salinity using NaCl, showed adverse effects on viability, germinationand tube growth of pollen, besides enhancing the bursting ofpollen. The endogenous levels of various metabolites in pollenwere also affected. Pollen grains from salinized plants hadmore soluble carbohydrates, free amino acids, especially proline,phenols and DNA and less starch, protein and RNA compared tothe non-saline controls. Salinity also resulted in the accumulationof ions such as Na+, K+ and Cl while it caused a reductionin the boron content of pollen. These metabolic disturbancespossibly lead to decreased viability, germination and tube growthof pollen thereby resulting into a reduction in reproductivecapacity of the plants under salt stress. Zea mays L., maize, pollen, viability, germination, salt stress 相似文献
7.
Azetidine-2-carboxylic acid (AZC), which occurs naturally inLiliaceous plants, is reported to be a proline (pro) analoguePlant cell walls contain extensin, which is richin hydroxyproline (hyp). Peptidyl hyp arises through hydroxylationof peptidyl pro followed by glycosylation (arabinose attachment)of hyp Because AZC replaces peptidyl prolyl residues, it maybe a useful tool for evaluating the significance of hyp-o-arabinoselinkages in cell elongation. Therefore, we determined the effectof AZC on [14C]pro uptake, incorporation and conversion to wall-bound[14C]hyp in relation to elongation of lily pollen tubes whosewalls consist, in part, of hyp-containing glycopeptides TheAZC suppressed pollen germination 942 per cent (110mM) and subsequent tube elongation 4054 per cent (0·11mM without affecting respiration In contrast, similar hyp concentrationswere without effect on tube elongation Whereas uptake of [14C]prowas 16·56·2 per cent of the control at0·11 mM AZC, [14C]leucine uptake was 8525per cent of the control. Light microscope radioautography revealedfewer silver grains over tubes elongated in 0·11mM AZC than in its absence. Incorporation of [14C]pro into tnchloroaceticacid (TCA)-precipitable cytoplasm was reduced by only 10 percent at 0·011 mM but 43 per cent at 10 mM AZCGel filtration of cytoplasm from pollen germinated without AZCbut with [14C]pro resulted in labelled void volume (V) and threeretarded peaks (RIIII) Incorporation into V and RI wasinhibited at both 0·01 and 1 mM AZC These AZC concentrationsreduced conversion of [14C]pro to wall-bound hyp by 20 percent However, total incorporation of [14C]pro into salt-water-purifiedwall fractions was suppressed 4753 per cent (0·11mM AZC). Lilium longiflorum, lily, hydroxyproline, proline, azetidine-2-carboxylic acid, pollen, pollen tube elongation 相似文献
8.
The effects of blue light (B) pretreatments on internode extensiongrowth and their possible interaction with phytochrome mediatedresponses were examined in Sinapis alba seedlings grown for11 d under 280 µmol m2 s1 of continuousblue-deficient light from low pressure sodium lamps (SOX). SupplementaryB (16 µmol m2 s1) caused no detectable inhibitionof the first internode growth rate under continuous SOX, butgrowth rate was inhibited after transfer to darkness. This effect,and the growth promotion caused by far-red bend-of-day' lightpulses were additive. The addition of B at 16 µmol m2s1 during 11 d, or only during the first 9 or 10 d orthe latest 0.75, 1 or 2 d of the SOX pretreatment caused approximatelythe same extent of inhibition after the transition to darkness.A single hour of supplementary B before darkness caused morethan 50% of the maximum inhibition. However, 24 h of lower fluencerates of B (4 or 7 µmol m2 s1) were ineffective.Covering the internode during the supplementary B period didnot prevent the response to B after the transition to darkness.Far-red light given simultaneously with B (instead of the SOXbackground) reduced the inhibitory effect of B. Above a given threshold fluence rate, B perceived mainly inthe leaves inhibits extension growth in subsequent darkness,provided that high phytochrome photo-equilibria are presentduring the irradiation with B. Once triggered, this effect doesnot interact significantly with the end-of-dayphytochrome effect. Key words: Blue light, extension growth, phytochrome 相似文献
9.
When ripe, viable pollen of Pinus contorta, Pinus nigra, Piceasitchensis, Abies alba and Cedrus deodara is germinated on asuitable artificial substrate, the process of pollen tube growthbegins 1236 h later, according to the species. The tubeemerges at the leptoma, a structurally specialized site in thepollen wall, and the early tube wall is continuous with thetwo microfibrillar intine strata within the grain. Later inpollen tube development, when cytoplasmic zonation has beenestablished, only the inner of these two wall layers is differentiated. Cytochemical methods show that, during hydration and throughoutthe period of tube growth in culture, proteins are releasedfrom the pollen grains; before germination most conspicuouslyfrom the leptoma, subsequently from the tube itself. The emissioncontains a number of hydrolytic enzymes and a non-catalyticmoiety. Gel-electrofocusing reveals that the hydrolases releasedfrom germinating Pinus contorta pollen include several acidphosphatase and esterase isozymes, and that there are differencesbetween the composition of the emission and the spectrum ofsoluble proteins extracted from the pollen grains before germination.Analysis by immunodiffusion demonstrates that two componentswith antigenic characteristics present in the quiescent pollengrains are represented in the emission. The possible utilityof the released components in the biology of conifer reproductionis discussed. Pinus contorta, Pinus nigra, Picea sitchensis, Abies alba, Cedrus deodara, lodgepole pine, Austrian pine, Sitka spruce, European silver fir, deodar, pollen tube, pollen germination, protein release, isoelectric focusing 相似文献
10.
Pollen collected from maize plants raised under 0, 80, 120 and160 mequiv 11 salinity were used to determine the activitiesof amylase and invertase after 0 and 45 min of incubation inthe liquid basal germination medium. Amylase activity was higherin the ungerminated pollen collected from 120 and 160 mequiv11 salinity while those pollen from lower salinity didnot show detectable amylase activity. However, 45 min afterincubation, the trend was reversed. Pollen collected from plantsraised under saline conditions showed increased invertase activitywhich further increased after 45 min of incubation in the basalgermination medium. The significance of changes in the activitiesof these hydrolytic enzymes in relation to pollen tube growthis discussed. Zea mays, salinity, pollen, amylase, invertase 相似文献
11.
Gibberellic acid (GA3) at 58 µM, indoleacetic acid (IAA)at 29 µM, and (2-chloroethyl) phosphonic acid (Ethephon)at 70 µM promoted pollen tube growth in Crotalaria junceapollen suspension cultures both in water and basal medium. GA3stimulated [ l-14C]acetate incorporation into total lipids inboth media, whereas IAA enhanced incorporation in water culturesonly. On the contrary, Ethephon reduced the label in total lipidswhen supplemented in basal medium. Based on [l-14C lacetateincorporation into different phospho- and glycolipids, it isproposed that these growth regulators have a definite role inthe biosynthesis of lipid components of the membranes. 相似文献
12.
Germination of Pinus roxburghii pollen was observed to be phytochrome-controlled.The red and far-red light affected the activities of succinatedehydrogenase and glucose-6-phosphate dehydrogenase in a mannercharacteristic of enzyme induction by phytochrome. Activitiesof peroxidase and malate dehydrogenase were not affected byred and far-red lights in this system.
1This research was supported by the Indian Council of AgriculturalResearch, New Delhi and forms a part of the Ph.D. dissertationsubmitted to the Punjab Agricultural University, Ludhiana byA.K.D.
2Present address: Botany Department, The Australian NationalUniversity, Canberra, ACT 2600, Australia. (Received December 25, 1978; ) 相似文献
13.
CRAKER LYLE E.; ZHAO SHU YING; DECOTEAU DENNIS R. 《Journal of experimental botany》1987,38(5):883-888
Craker, L. E., Zhao, S. Y. and Decoteau, D. R. 1987. Abscission:response to red and far-red light.J. exp. Bot. 38: 883888. The dose-response and time relationship of red and far-red lightin the inhibition and promotion, respectively, of dark-inducedleaf abscission was quantified using cuttings of coleus (ColeusBlumei Benth.). A continuous photon flux of approximately 15nM m2 s1 of red light was sufficient to preventleaf abscission. Abscission was promoted by exposure to a photonflux of approximately 10 nM m2 s1 of far-red lightThe inhibition of abscission by red light could be reversedby treatment with far-red and the promotion of abscission byfar-red light could be reversed by treatment with red lightThe data were consistent with a phytochrome receptor systemlocated in the leaves that controlled the presence of an abscission-inhibitingsubstance in the abscission zones. Key words: Abscission, Coleus Blumei, far-red light red light 相似文献
14.
Video images of the distributional pattern of membrane-associatedcalcium (Ca2+) and calmodulin (CaM) have been documented andanalysed during pollen hydration, germination and tip growthin Nicotiana tabacum. Digitization of fluorescence microscopeimages of chlorotetracycline (CTC) and fluphenazine (FPZ)-fluorescenceemissions reveal that there is a maximum concentration of membrane-associatedCa2+ and also CaM in the vicinity of germination apertures ofhydrated pollen. With the onset of germination relatively higheramounts of Ca2+ and CaM were found to regionalize towards theaperture through which the pollen tube would emerge Both shortand long growing pollen tubes manifest tip-to-base Ca2+ andCaM gradients which are disturbed in non-growing tubes. Tubegrowth and the Ca2+-gradient were significantly affected byvanadate and verapamil suggesting that both a vanadate-sensitiveCa2+-transport system and verapamil-sensitive Ca2+ channelsare involved in maintaining Ca2+ homeostasis during pollen germinationand tube growth. The possible interactions of Ca2+ and CaM withdifferent cytoskeletal proteins modulating organelle movementare also briefly discussed. Image analysis, calcium, calmodulin, Nicotiana tabacum L., pollen germination, pollen tube, tip growth, Ca2+-channels, Ca2+ transport ATPase 相似文献
15.
Germination of lettuce seeds (Lactuca sativa L. cv. Grand Rapids)was examined in the presence of various doses (105.0103.0M) of gibberellic acid applied at various times (hour 08)of soaking. Germination promotion by gibberellic acid was greateras the dose of gibberellic acid was increased and attenuatedwith the length of the presoaking period. As an exception, ca.95% germination was always evoked by the largest dose (103M) of gibberellic acid given at any time of soaking. The dose-responsecurve obtained for each presoaking period had a distinct sigmoidalprofile. Synergistic and photoreversible promotion by red light of thegibberellin-induced germination was also investigated. Far-redlight pulse given 6 hr after the red pulse was still effectivein removing the red light action. Application of enzyme kineticsto the gibberellin action and also to the synergism betweengibberellin and red light was suggested.
1National Institute for Basic Biology, Myodaiji, Okazaki 444,Japan. (Received December 18, 1979; ) 相似文献
16.
The Effect of Brassica oleracea Stigma Extracts on the Germination of B. oleracea Pollen in a Thin Layer Chromatographic Bioassay 总被引:1,自引:0,他引:1
Hodgkin, T. and Lyon, G. D 1986. The effect of Brassica oleraceastigma extracts on the germination of B. oleracea pollen ina thin layer chromatographic bioassay.J. exp. Bot. 37:406411. A procedure for germinating Brassica oleracea pollen on thinlayer chromatography plates pretreated with 20 mol m3tris(hydroxymethyl) methyl-aminopropanesulphonic acid (TAPS)buffer, pH 8·0 has been devised and used to detect pollengermination inhibitors in B. oleracea stigma extracts. Inhibitory zones in extracts of stigmas, unpollinated, or collected0·5, 4, 8 and 24 h after self- or cross-pollination,differed little in RF values and sizes. Extracts of stigmascollected 1 h and 2 h after self-pollination gave a small additionalinhibitory zone which was not detected in 1 h and 2 h cross-pollinatedstigma extracts. The results showed some differences from thoseobtained using Petunia hybrida pollen germinated on T.L.C. platesthat were not pretreated with buffer. The nature of the differencesbetween the two bioassays is discussed and some possible reasonsfor them indicated. Key words: Pollen, germination inhibitors, self-incompatibility, Brassica oleracea 相似文献
17.
This paper describes how different wavelengths of light regulatespore germination in the fern Ceratopteris richardii. This speciesdoes not exhibit any dark germination. Maximum photosensitivityof the spores is reached 7 to 10 d after imbibition. An increasein the red light fluence above the threshold fluence of 1016quanta.m2 leads to a corresponding increase in germination.In sequential irradiation experiments, farred light can reversethis red light-mediated germination to the level observed withthe far-red light control. Blue light fluences above 1020 quanta.m2can also block the germination response to red light. Moreover,this antagonistic effect of blue light is not reversed by subsequentirradiation with red light. It is therefore concluded that phytochromeand a distinct blue light photoreceptor control C. richardiispore germination. These interpretations are entirely consistentwith the published literature on other fern genera. (Received November 28, 1986; Accepted April 6, 1987) 相似文献
18.
Hydration of pollen of Narcissus pseudonarcissus was retardedand germination blocked in media with supra-optimal concentrationsof osmoticum. Activation of the grains, expressed in circulatorymovement in the vegetative cell, was not blocked. Wall developmentwas disrupted, and pectic material and callose were depositedthroughout. In the absence of calcium many grains burst on hydration.The survivors showed evidence of activation, but few tubes wereformed. In medium with supra-optimal Ca2+, activation proceeded,but where tube tips were produced they became occluded withcallose, which eventually formed a general lining to the intine.Nifedipine, a Ca2+-blocker, did not prevent activation at 104M, but reduced callose deposition and inhibited polarized movementin the vegetative cell. Prominences formed at the germinationsites were mostly low and rounded. During recovery in normalmedium, tube tips with normal callose linings were formed. Colchicine,a microtubule inhibitor, had no effect on activation or germination.Cytochalasin D, an actin inhibitor, prevented activation ofthe vegetative cell, but did not arrest all wall deposition.Movement began soon after transfer to normal medium, and somegrains produced adventitious tube tips. While Ca2+ appears notto be essential for activation, these results may be interpretedas indicating links in the normal course of germination betweenthe initial Ca2+ influx at the potential germination sites and:(a) polarization of movement in the vegetative cell, probablyrelated to re-orientation of the actin cytoskeleton; and (b)patterned deposition of callose, which appears to have an importantmorphogenetic role. Narcissus pseudonarcissus, pollen activation, pollen germination, osmotic effects, actin cytoskeleton, nifedipine, cytochalasin D, colchicine, role of Ca2+ flux 相似文献
19.
Development of axillary shoots was induced in embryonic axesof the dipterocarp Shorea roxburghii G. Don. cultured on a modifiedMS medium containing 6-benzyl-aminopurine (BAP) at an optimumconcentration of 5 mg I1. Excised axillary shoots wereused in multiplication and rooting experiments. Vigorous rootdevelopment occurred in shoots supported on filter paper bridgesin liquid medium containing naphthaleneacetic acid (NAA) andindolebutyric acid (IBA) (0.1 mg I1 each). Shorea roxburghii, Dipterocarpaceae, tissue culture, plantlet formation 相似文献
20.
We examined the effect of pretreatments (18 h at 5 µmoldm3) with abscisic acid, the ethylene-releasing substanceEthephon, gibberellic acid, indoleacetic acid,kinetin and zeatin on nitrate uptake and in vivo nitrate reductaseactivity (NRA) in roots of nitrogen-depleted Phaseolus vulgarisL. Nitrate uptake showed an apparent induction pattern witha steady state after about 6 h, in all treatments. The nitrateuptake rate after 6 h was unaffected or at most 30% lower aftertreatments with the plant growth regulators. Gibberellic acid, kinetin and zeatin induced substantial NRAin roots in the absence of nitrate, whereas Ethephon enhancedNRA only during nitrate nutrition. Kinetin-induced NRA (Ki-NRA)was maximal after a pretreatment at 1 µmol dm3,and showed a lag phase of 68 h. Ki-NRA was additive tonitrate-induced NRA (NO3-NRA) for at least 24 h, independentof the induction sequence. After full induction, Ki-NRA approximated20% of NO-3-NRA. Abscisic acid counteracted the developmentof Ki-NRA, but not of NO3-NRA. Cycloheximide and tungstatewere equally effective to suppress the development of nitratereductase activity after supply of kinetin or NO3. Our data are consistent with the operation of two independentenzyme fractions (Ki-NRA and NO3-NRA) with apparentlyidentical properties but with separate control mechanisms. Theabsence of major effects of plant growth regulators on the time-courseand rate of nitrate uptake suggests that exogenous regulators,and possibly endogenous phytohormones are of minor importancefor initial nitrate uptake. The differential effect of someregulators on nitrate uptake and root NRA furthermore indicatesthat the processes of uptake and reduction of NO3 arenot obligatory or exclusively coupled to each other. 相似文献