摘要:

Ageing of potato tuber discs markedly increases the rate of phosphate uptake. This increase is partially prevented by the presence of indoleacetic acid (IAA: 50 μM) in the ageing medium.32P distribution among the various phosphorylated fractions (P1, organic soluble phosphate, acid‐insoluble phosphate) was carried out after 24 h of ageing in the presence of IAA. An equal inhibition of the labelling rates of each of the different fractions is induced by the hormone. No important effect on respiration and ATP content was observed. Moreover, IAA neither changes the total phospholipid content nor the relative distribution of32P between the components. These results support the hypothesis that IAA acts specifically on the development of uptake mechanisms during the ageing peri

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04487.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The different phases of development of the apical meristem in two ecotypes ofArabidopsis thaliana(L.) Heynh. [one French (a quantitative long‐day plant), the other one Swedish (an absolutely cond‐requiring plant)] were established, under conditions either inductive or not inductive of flowering. Then the effects of gibberellins (GA3, GA4/7) and cytokinin (6‐BA) on these ecotypes were studied at different stages of their ontogenic development. The rate of plant growth was estimated by measuring the plastochron duration. The activities of the different apical zones were determined with cytochemical methods and by histoautoradiography after incorporation of 3H‐thymidine into DNA. When treated during the vegetative stage, i.e. at a young age (French ecotype) or in absence of cold treatment (Swedish ecotype) flowering was not induced. The tested chemicals had similar effects: at first a stimulation of the phylogenetic activity of the cells of the lateral zone and of the rib meristem and, after extended treatments, a differentiation of the axial cells of the meristem and, as a result, an inhibition of flowering. On the other hand, the different hormonal applications on meristems which have reached the intermediate stage, were effective in inducing the reproductive state. The activity of the central cells already in the process of dedifferentiation was increased and, by this, flowering was p

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04488.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Adventitious roots develop in stem cuttings ofPhaseolus aureusRoxb. seedlings when treatment with indole‐butyric acid (IBA) is followed by treatment with boron. Root development varies according to the age of seedlings from which cuttings are taken. Increased root number is associated with expansion of the first leaf pair but subsequently declines, whereas root growth increases with increasing seedling age. Removal of leaves furing the first 72 h of treatment impairs root initiation whereas root growth is diminished by removal of leaves at any time during the first 120 h of treatment. IBA stimulates movement of14C‐IAA out of leaves. Vitamin D2and myo‐inositol stimulate rooting of intact cuttings provided cuttings are subsequently supplied with boron. Hypocotyls excised from cuttings pretreated with IBA develop roots in response to myo‐inositol in the absence of boron. It is proposed that endogenous auxin, arising in the leaves, and myo‐inositol have roles in root initiation whilst the role of boron is suggested as one of initiating or maintaining transport from t

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04489.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The chromatographic behaviour of abscisic acid (ABA), indole‐3‐acetic acid (IAA), phenylacetic acid (PAA), and gibberellins A1, A4, A8, A9, A13and A20on columns of Sephadex LH‐20 and insoluble poly‐N‐vinylpyrrolidone (PVP) eluted with buffers of different pH values is described. PVP shows considerable batch differences that must be carefully checked. Chromatography of acidic ethyl acetate‐soluble fractions of Scots pine (Pinus sylvestrisL.) extracts at pH 4.5 resulted in great losses of phytohormones, due to poor solubility of the extracts. If the extracts were applied to the column dissolved in buffer of pH 7.5, subsequent elution at pH 4.5 was possible with only small losses. The performance of the chromatographic column was strongly affected by the application volume. A combined PVP/Sephadex LH‐20 column eluted at pH 4.5 allows remarkable purification of pine and spruce (Picea abies(L.) Karst.) extracts, collection of IAA in a fraction that can be directly analyzed by e.g. the indolo‐α‐pyrone method, and collection of another fraction containing ABA, PAA and probably most of the known C19‐gibberellins; whereas the C20‐gibberellin A13is e

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04490.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Microdistribution patterns of Mn in the leaf tissues of 9 plant species,Quercus mongolicaFisch. var.grosseserrataRehd. et Wils.,Lindera erythrocarpaMakino,Rhus trichocarpaMiq.,Ilex crenataThunb. varpaludosa(Nakai) Hara,Acer sieboldianumMiq.,Acanthopanax sciadophylloidesFranch. et Savat.,Clethra barbinervisSieb. et Zucc.,Pieris japonica(Thunb.) D. Don andRhododendron semibarbatumMaxim. were studied by means of a wavelength dispersive type X‐ray microanalyzer in conjunction with cryostage. The results showed that Mn, in general, was highly concentrated in the epidermal, palisade and spongy parenchyma cells of the leaf tissues of the investigated plants with optimal Mn suppl

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04491.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The regulation of hypocotyl extension in light‐grownChenopodium rubrumL. seedlings by light analogous to dense vegetation canopy shade has been monitored. Hypocotyl extension was controlled by both the quantity and quality of the actinic light. At the higher of the two background photon fluence rates which were used (10.0 μmol m−2s−1in the 400–700 nm waveband), increasing the proportion of phytochrome calculated to exist as Pfr resulted in greater inhibition of growth. At the lower photon fluence rate (1.0 μmol m−2s−1in the 400–700 nm waveband), a biphasic response was observed in which minimum inhibition was observed at intermediate photoequilibria. Although photosynthesis was not directly involved in the photomorphogenetic responses, it did play an indirect quantitative role in determini

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04492.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Glutamine synthetase (l‐glutamate: ammonia ligase, ADP‐forming, EC 6.3.1.2) in bark tissue of the apple (Malus domesticaBorkh. cv. Golden Delicious) was partially purified and characterized. The Mn2+‐ and Mg2+‐dependent activities were maximal at pH 7.2 and 7.5, respectively. The enzyme was almost completely inactivated within two weeks at 0°C. Both Mg2+and β‐mercaptoethanol were effective in stabilizing the enzyme during storage. The enzyme was protected from thermal inactivation at 60°C by the addition of Mg2+and ATP. One‐tenth mM phenylmercuric acetate inhibited the Mg2+‐dependent activity by 50%. Equimolar dithiothreitol protected the enzyme from this inactivation. The Kmvalues of the enzyme were 0.27, 7.35, and 0.69 mMfor ATP, glutamate, and NH2OH, respectively. The constant for NH+4was an order of magnitude higher in the presence of Mn2+than Mg2+.When the amino acids were externally added to the reaction mixtures, the measurement of Piexhibited a higher degree of enzyme inhibition than the measurement of γ‐glutamyl monohydroxamate (GHA). Ten mMhistidine inhibited the Mg2+‐ and Mn2+‐dependent activities by 26 and 45% respectively. TwentymMaspartate (d,l‐form) inhibited the enzyme 30% in the presence of either Mg2+or Mn2+. Aspartate (Mg2+‐dependent) and histidine (Mn2+‐dependent) inhibited the enzyme competitively with respect to glutamate, the estimated inhibition constants being 17.6 and 1.6 mM, respectively. At 10 mM, amino acids such as tryptophan, arginine, alanine and citrulline inhibited enzyme activity from 1 to 18%. Glutamine stimulated the Mg2+‐dependent activity 25% at 25 mMwhen GHA was measured. Glutamine

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04493.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Urease is induced by urea inEvernia prunastri(L.) Ach. thallus, but the enzyme becomes inactive from the fifth hour of culture, this process being more complete when the thallus is incubated in white light than when the thallus is aging in darkness. Dithiothreitol prevents this inactivation to some extent by reduction (or protection) of ‐SH groups in the protein. In vivo inactivation, in darkness as well as in the light, is accompanied by increase in the molecular mass of the enzyme; this pattern is not greatly changed by dithiothreito

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04494.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The activities ofN6‐benzyladenine (BA) and its 9‐substituted methyl, methoxymethyl, tetrahydropyranyl, cyclopentyl, and cyclohexyl analogs were determined for the promotion of lettuce seed (Lactuca sativaL. cv. Grand Rapids) germination. Cytokinin concentrations used were 10−4, 10−5, 10−6and 10−7M. All seeds were incubated under total dark conditions at 28 ± 1°C. After 48 h the percentage of germination was recorded. A comparison of means based on Duncan's Multiple Range Test allowed for a ranking of cytokinin activities for the promotion of lettuce seed germination. The activities were: BA = 9‐tetrahydropyranyl BA>9‐methyl BA>9‐methoxymethyl BA>9‐cyclopentyl BA>9‐cyclohexyl BA. The results were significant at the 95% confidence level as determined by analysis of variance. In order to study the metabolism of a cytokinin, lettuce seeds were incubated with 9‐methyl‐BA‐methylene‐14C. The labeled cytokinin was prepared by refluxing benzylamine hydrochloride (methylene‐14C) with an equal molar ratio of 6‐chloro‐9‐methylpurine. Final cytokinin concentration was 10−5M. Incubation periods were 2, 4, 8, 12, 16 and 20 h at 28 ± 1°C under total dark conditions. At the end of the various time periods the seeds were extracted with 70 percent methanol. The resulting extracts were purified and radioactive metabolites identified by solvent fractionation, Sephadex LH‐20 column chromatography, and paper chromatography. Co‐chromatography with authentic standards in the appropriate solvent system revealed that the metabolites were 9‐methyl BA,N6‐benzyladenosine‐5′‐monophosphate, andN6‐benzyladenosine. The results lend support to the theory that the cytokinin ribonucleotide serves as a storage form which is converted to the acti

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04495.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Treatment of microsomal membranes from cotyledons ofPhaseolus vulgariswith ozone raises the liquid‐crystalline to gel lipid phase transition temperature and results in the formation of distinct domains of gel phase lipid in the membranes. Liposomes prepared from the total lipid extracts of ozone‐treated membranes undergo phase separations just a few degrees below the transition temperature for intact membranes, indicating that the formation of gel phase lipids is largely attributable to ozone‐induced alterations in the membrane lipids. Levels of unsaturated fatty acids as well as the sterol to phospholipid ratio are markedly reduced in the ozone‐treated membranes, and the neutral lipid fraction from treated membranes shows, an increased propensity to induce the formation of gel phase phospholipid when incorporated into liposomes of egg phosphatidylcholine. Since gel phase phospholipid also forms in naturally senescing plant membranes and appears to be attributable to changes in the neutral lipid fraction, the effects of natural senescence and ozone on membranes have been c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1981.tb04496.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY