摘要:

Alkaline hydrolysis liberated ferulic and diferulic acid from polysaccharides of theAvenacoleoptile (Avena sativaL. cv. Victory I) cell walls. The amount of the two phenolic acids bound to cell walls increased substantially at day 4–5 after sowing, when the growth rate of the coleoptile started to decrease. The level of these acids was almost constant from the tip to base in 3‐day‐old coleoptiles, but increased toward the basal zone in 4‐ and 5‐day‐old ones. The ratio of diferulic acid to ferulic acid was almost constant irrespective of coleoptile age and zone. An increase in the amount of ferulic and diferulic acids bound to cell wall polysaccharides correlated with a decrease in extensibility and with an increase in minimum stress‐relaxation time and relaxation rate of the cell wall. The level of lignin in the cellulose fraction increased as coleoptiles aged, but this increase did not correlate with changes in mechanical properties of the cell walls. These results suggest that ferulic acid, ester‐linked to cell wall polysaccharides, is oxidized to give diferulic acid, which makes the cell wall mechanically rigid by cross‐linking matrix polysaccharides and results in limited cell extension growth. In addition, it is probable that the step of feruloylation of cell wall polysaccharides is rate‐limiting in the formation of in‐termolecular bridges by diferulic acid inAvena

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08706.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Tomato (Lycopersicon esculentumMill.) genotypes varying in intrinsic firmness were examined to determine the quantitative relationships between polygalacturonase (EC 3.2.1.15) activity, firmness and other ripening parameters including rate (days from mature‐green to full red) and intensity (rate of ethylene production at climacteric peak) of ripening. Texture, respiration and ethylene production were monitored in the immature‐green through the red (ripe) stages of development. Polygalacturonase activity was measured by direct assay of salt‐extractable wall protein or by monitoring the release of pectins from isolated, enzymically active wall. In all fruit, polygalacturonase activity was highly correlated with pericarp softening, but only moderately correlated with softening of whole fruit (r = 0.920 and 0.757, respectively). Polygalacturonase activity was positively correlated with cell‐wall autolytic activity in pink (r = 0.969) and red (r = 0.900) fruit. Firmer genotypes exhibited lower rates of respiration and ethylene production during ripening. Polygalacturonase activity in isolates prepared from fruit at the climacteric peak was positively correlated with ethylene production and respiration, and negatively correlated with days to ripening (r = 0.929, 0.805, and ‐0.791, respectively). The data demonstrate the importance of selecting the appropriate method of firmness determination and are consistent with the hypothesis that pectin fragments released by polygalacturonase contribute to the production of autocatalytic (system II)

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08707.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The effects of the naturally occurring polyamines, spermine, putrescine, and spermidine were explored on mitochondrial state 3. state 4, and uncoupled respiration activities, ADP/O ratio, respiratory control ratio of pepper (Capsicum annuumL. cv. Early Cal Wonder) and avocado (Persea americanaMill. cv. Booth‐8 or Simmonds) mitochondria oxidizing either succinate, external NADH, malate, α‐ketoglutarate or tetramethyl‐p‐phenylenediamine. Abnormally high concentrations of spermine and spermidine such as might occur during chilling stress of these chilling‐sensitive fruits were detrimental to several oxidase activities, especially to external NADH oxidase. State 3 respiration for NADH oxidase was inhibited more than 70% by 10 mMspermine. The spermine inhibition of uncoupled NADH oxidase was not reversed by the presence of divalent cations including Ca2+, Mg2+, Mn2+, and Sr2+at concentrations up to 10 mMor by 100 mMKCl. The inhibition primarily affected the Vmax. Other possible sites of polyamine interactions are

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08708.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Filtration stress, consisting in the rapid filtration ofAcer pseudoplatanusL. cell suspension cultures, resulted in significant differences between the peroxidases (EC 1.11.1.7) released during cell growth and those released after filtered cells were resuspended in fresh medium (recovery medium). These differences concerned mainly modifications of (i) the pH optimum of peroxidase activity (guaiacol as electron donor), (ii) the number and the pI values of the peroxidase isoenzymes as shown by isoelectric focusing, and (iii) the molecular weights of the different peroxidase fractions determined by gel filtration chromatography. The presence of 1 mMLi+in the recovery medium inhibited the release of peroxidase and this effect was partially reversed by K+. The release of peroxidase by stressed cells was also strongly inhibited by Na2CO3in the recovery medium. The results presented are consistent with the proposal that the characteristic isoperoxidase patterns induced by filtration stress might be used as a model to study the response of plant cells to stress.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08709.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The effects of supplied ammonium and nitrate on the amino and organic acid contents and enzyme activities of cell suspension cultures ofAcer pseudoplatanusL. were examined. Regardless of nitrogen source the pH of the culture medium strongly affected the malate and citrate contents of the cells; these organic acid pools declined at pH 5, but increased at pH 7 and 8. Over a period of two days, ammonium had little effect on the responses of the organic acid pool sizes to the pH of the medium. In contrast, ammonium had a strong influence on amino acid pool sizes, and this effect was dependent on the pH of the medium. At pH 5 there was no increase in cell ammonium or amino acid contents, but at higher pH values cellular ammonium content rose, accompanied by accumulation of glutamine, glutamate and asparagine. Over several days, supplied ammonium led to an increase in activity of glutamate dehydrogenase irrespective of any changes in internal ammonium and amino acid contents. If the pH of the medium was allowed to fall below pH 4 in the presence of ammonium, phosphoenolpyruvate (PEP) carboxylase activity declined to a very low value over several days; at higher pH, the activity of this enzyme, and that of NAD malic enzyme and NAD malate dehydrogenase, remained substantial irrespective of whether the nitrogen source was NH+4or NO‐

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08710.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Alteration of the electrical polarity in sections of maize (ZeamaysL. cv. Odesskaya‐80) coleoptiles and pea (Pisum sativumL. cv. Cubanecz) internodes by passing a weak electric current longitudinally (6 μA, anode placed at the apical end of the section) increased their elongation rate 2–3 fold with a lag period of 2.5 min. Inhibitors of polar auxin transport, e.g. N‐1‐naphthylphtalamic and 2,3,5‐triiodobenzoic acids and also ethylene glycol‐bis(β‐aminoethylether)‐N,N,N'N'‐tetraacetic acid (EGTA), a chelator of divalent cations, decreased the growth rate of the sections and inhibited the growth‐stimulating effect of the electric current. The observed acceleration of growth of axial plant organs under the action of a weak electric current is suggested to be connected with changes in the mode of action of the basipetal a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08711.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Partition and sorption characteristics of the cytokinin N‐(phenylmethyl)‐lH‐purine‐6‐amine (N6‐benzyladenine, BA) in two model systems were studied at 25°C. Apparent partition coefficients (KpH) for BA in ann‐octanol:water (buffer) system were independent of BA concentration but decreased with increasing buffer concentration (ionic strength). A plot of KpHvalues versus pH (2 to 12) was a bell‐shaped curve. At pH 2 or 12, KpHvalues were low (less than 2). As pH approached neutrality, KpHvalues increased approximately 20‐fold. Estimates of pK1(3.3) and pK2(10.7) values for BA were obtained from these data. The accuracy of this approach to determining pK values was verified with 2‐(1‐naphthyl)acetic acid (NAA). Correction of KpHvalues for dissociation effects on BA yielded partition coefficients (K) whose overall mean was 37. Sorption of BA by cuticles enzymatically isolated from abaxial and adaxial surfaces of mature rubber plant (Ficus elasticaRoxb. cv. decora) leaves was initially rapid, however equilibrium was not reached by 432 h. At pH 2, sorption was low (approximately 5 μmol kg−1), whereas at pH 6 sorption increased approximately 11‐fold. Sorption by abaxial cuticular membranes (CM) and dewaxed CM (DCM) was slightly higher than corresponding adaxial CM and DCM. Using natural logarithm values, KpHdata were linearly‐correlated with CM (r = 0.98) and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08712.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Root and shoot temperatures were varied independently to determine the importance of root temperature during cold acclimation. Spinach (Spinacia oleraceaL. cvs Harbin and Bloomsdale) plants were subjected to 20/20°C. 20/5°C, 5/20°C, and 5/5°C (shoot/root) temperature treatments. Leaf freezing tolerance, water potential, stomatal resistance, osmotic potential, and water content were measured at 0.25. 1.25, 3.25, and 7.25 days of treatment. There was no change in freezing tolerance or the water relations of the 20/20°C treated plants during the course of the experiment. Freezing tolerance was increased by the 5°C shoot temperature treatments, but was not enhanced by water stress induced by the low root temperature. Leaf water potential and water content decreased and stomatal resistance increased within 6 h in the 20/5°C plants. By day 3, osmotic potential began decreasing in the 20/5°C plants. Leaf water content, osmotic potential, and water potential decreased more gradually in plants grown with 5°C shoot temperature, irrespective of root temperature. Decreased water content and osmotic potential were not correlated with increased freezing tolerance as reported for other herbaceous cro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08713.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Effects of amphiphilic derivatives of glycine esters of the general formula (CH3)3N+CH2COOCnH2n+1Cl‐ (n = 10, 12, 14, 16) on membrane potential and conductance in internodal cells of the algaNitellopsis obtusawere studied. The compounds decreased the potential difference between vacuole and external medium and increased the electric conductance. The effects depended on the length of the alkyl chain (n) and the concentration of these quaternary ammonium salts. Light‐induced hyperpolarization was suppressed by the salts. We suggest that the ammonium salts inhibit the electrogenic proton pump in the plasmalemma and enhance the passive efflux of Cl‐ from the algal

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08714.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Growth analysis techniques are used to test the hypothesis that chilling induces curd (flower) initiation in the cauliflower (Brassica oleraceaBotrytis L. cv. Perfection) through inhibiting leaf growth, thereby increasing the availability of growth factors to the stem apex and enabling differentiation of the curd. Effects of chilling on leaf growth and curd induction are compared in juvenile and mature, vegetative plants. Chilling at 5°C reduced dry matter accumulation in the total leaf complement by ca 60% in juvenile plants and 40% in mature plants, compared to control plants growth at 20°C. Juvenile plants showed slower rates of leaf initiation than mature plants. Leaf initiation was retarded by chilling in both plant types with the most marked effect seen in the juvenile plants. This was consistent with dry matter availability to the stem apex limiting differentiation more severely in juvenile plants than in mature plants. The rate of dry matter accumulation in existing leaves, however, was faster in juvenile plants than in mature plants at 20°C. Plants that were juvenile during chilling produced an average of 43 leaves below the curd whereas those that were mature produced 25.Dry matter accumulation in younger leaves was more markedly inhibited by chilling than in older leaves. Chilling also reduced the rate at which enlarging leaves became positionally more remote from the stem apex. Possible roles for such leaves in regulating apical development are consider

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb08715.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY