摘要:

A competitive indirect enzyme-linked immunosorbent assay (ELISA) was developed for the rapid quantitation of the glycosylated and deglycosylated forms of the monomeric soluble extensin precursor subunits P1 and P2. A log-linear response range for each kind of precursor in the competition curve was between 0.01 and 100 nanograms per milliliter.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

The objective of this research was to determine the changes in fructan content and the activity of fructosyltransferases during the growth of wheat seeds (Triticum aestivumL. Thell, cv Caldwell). The total fructan content of the seeds decreased significantly during seed growth. The trisaccharide and tetrasaccharide content increased from 6 to 28 days post anthesis (DPA) and then declined, but these changes are not statistically significant. The content or concentration of longer chain polymers did decline significantly (64.55-6.52 milligrams per gram dry weight). Free fructose also decreased significantly during seed growth indicating that the fructose liberated from the decrease in fructan content was utilized by the seed. Sucrose increased significantly from 6 to 12 DPA, then declined significantly from 12 to 28 DPA. Sucrose:sucrose fructosyltransferase activity was greatest from 6 to 12 DPA (averaging 0.16 micromole of fructose transferred per seed per hour), then declined rapidly (0.04 micromole of fructose transferred per seed per hour). The estimated activity of fructan:fructan fructosyltransferase followed a similar pattern. The increase in sucrose concentration and high enzyme activity suggests that fructans were synthesized during the lag phase of seed growth.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

d-Galactose has been shown to have toxic and growth inhibitory effects in plants. When applied at levels of 50 millimolar to tobacco (Nicotiana tabacumL. cv Xanthi) leaf discs galactose caused a rapid increase in ethylene production during the first 2 days of incubation, followed by a rapid return to the basal level on the third day. This pattern of galactose-stimulated ethylene production was accompanied by increased formation of 1-aminocyclopropane-1-carboxylic acid (ACC), which accumulated without being metabolized to ethylene or to the ACC-conjugate. The inhibitory effect of galactose (50 millimolar) on the conversion of ACC of ethylene was relieved partially byd-glucose or sucrose (50 millimolar), and completely by CO2(10%), which were shown to enhance this conversion by themselves. Consequently, application of galactose plus any one of these compounds increased ethylene production and decreased free ACC levels. The data suggest that galactose toxicity may result in both an increased ethylene production as well as in accumulation of free ACC in aged discs. The increased ethylene production rates and ACC levels may, in turn, play a role in the development of symptoms associated with galactose toxicity.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

Addition of 5 micromolar Cu2+, Cd2+, and Zn2+was inhibitory to 10 micromolar H2O2-supported Hill activity (dichlorophenolindophenol reduction) and O2evolution in membrane preparation fromAnacystis nidulans. The reversal of Cd2+and Zn2+inhibition, in contrast to Cu2+, by exogenously added catalase (EC1.11.1.6) suggested that the former cations were inhibitory to H2O2degradation. Ascorbic acid (20 micromolar) supported 27% of the Hill activity which was insensitive to DCMU (10 micromolar) and the remaining activity, attributable to the DCMU sensitive process, was sensitive to inhibition by Cu2+only. It is suggestive that the action site of Cd2+and Zn2+is located between the electron donation sites of H2O2and ascorbic acid, while that of Cu2+is located beyond it. Electron donation by reduced glutathione was insensitive to DCMU and Cu2+, indicating that the action site of Cu2+is prior to its electron donation site. Further, the phenanthroline (10 micromolar) reversal of Cu2+inhibition of Hill activity suggested a tentative action site of Cu2+at the level of cytochrome.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

Two-dimensional gel electrophoresis was used to characterize the molecular mechanism of gibberellin-induced stem elongation in maize and pea. Dwarf mutants of maize (d-5) and pea (Progress No. 9) lack endogenous gibberellin (GA1) but become phenotypically normal with exogenous applications of this hormone. Sections from either etiolated maize or green pea seedlings were incubated in the presence of [35S] methionine for 3 hours with or without gibberellin. Labeled proteins from soluble and particulate fractions were analyzed by two-dimensional gel electrophoresis and specific changes in the patterns of protein synthesis were observed upon treatment with gibberellin. Polyadenylated mRNAs from etiolated or green maize shoots and green pea epicotyls treated or not with gibberellin (a 0.5 to 16 hour time course) were assayed by translation in a rabbit reticulocyte extract and separation of products by two-dimensional gel electrophoresis. Both increases and decreases in the levels of specific polypeptides were seen for pea and corn, and these changes were observed within 30 minutes of treatment with gibberellin. Together, these data indicate that gibberellin induces changes in the expression of a subset of gene products within elongating dwarfs. This may be due to changes in transcription rate, mRNA stability, or increased efficiency of translation of certain mRNAs.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

The percentage of soybean cell culture protoplasts permeabilized by electroporation was dependent on the voltage and the number of successive pulses that were applied. Best results were obtained with two 50 milliseconds, 400 volts per centimeter pulses after which 78% of the surviving protoplasts had been permeabilized to the fluorescent dye calcein. Quantitation of the volume of extracellular fluid taken up was performed using radioactive inulin (molecular weight 5000-5500). Typically between 20 and 40 nanoliters of fluid was taken up by 106protoplasts. Electroporation and hypotonic shock treatments (M Saleem, AJ Cutler 1986 J Plant Physiol 124: 11-21) were compared with respect to the volume of fluid taken up under optimum conditions. Electroporation produced 10 times more uptake than hypotonic shock treatment. In all experiments there was a direct relationship between the number of protoplasts lysed and both the amount of fluid taken up and the percentage of surviving protoplasts that were permeabilized.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

The rate of CO2assimilation and levels of metabolites of the C4cycle and reductive pentose phosphate pathway in an attached leaf of maize (Zea maysL) were measured over a range of intercellular CO2concentration (Ci) of 10 to 190 microliters per liter. The CO2assimilation rate was saturated at a Ci of around 175 microliters per liter. The levels of ribulose 1,5-bisphosphate and fructose 1,6-bisphosphate decreased substantially with increasing Ci. The levels of 3-phosphoglycerate, phosphoenolpyruvate (PEP), and pyruvate increased with increasing Ci. The level of dihydroxyacetone phosphate increased moderately from Ci of 10 microliters per liter to 20 to 50 microliters per liter and stayed almost constant over the rest of the range of Ci investigated. The levels of fructose 6-phosphate did not show any significant changes over the range of Ci. The levels of glucose 6-phosphate decreased slightly with increasing Ci. Although photosynthetically inactive pools of malate, asparate, and alanine could mask real changes in levels of the photosynthetically active pools of these compounds, the apparent levels of these compounds and the total amount of intermediates in the C4cycle (malate, aspartate, pyruvate, PEP, and alanine) increased with increasing Ci. The results suggest that there is carbon input into the C4cycle from the reductive pentose phosphate pathway which increases the level of total intermediates of the C4cycle with increasing Ci.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

Applications of indole-3yl-acetic acid (IAA) and abscisic acid (ABA) were done on two-day-old intact maize (cv LG 11) roots. The effect of the treatment on the root growth depends on their initial elongation rate. The slow growing roots were all inhibited by exogenous IAA and ABA at any concentrations used whereas for the fast growing roots their elongation was promoted by these two hormones at low concentrations. Quantitative analyses of endogenous IAA and ABA were performed using the gas chromatography-mass spectrometry technique. Detection and quantification of endogenous IAA and ABA were done on the zone of the root implicated in elongation. These techniques were achieved by electron impact on the IAA-Me-heptafluorobutyryl derivative and by negative ion chemical ionization with NH3on the ABA-Me ester derivative. A negative correlation between the growth and the endogenous content of these two hormones was obtained. ABA presented a larger range of endogenous level than IAA on the whole population of roots tested. When using applied IAA and ABA at different concentrations the same differentiating effect on the growth was observed. This allowed us to conclude that for identical concentrations, IAA has a more powerful effect on root elongation than ABA. Present results are discussed in relation to previous data related to the role of IAA and ABA in the growth and gravireaction of maize roots.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

Syringomycin, a peptide toxin produced by the phytopathogenPseudomonas syringaepvsyringaepreferentially stimulated (2-fold) the vanadate-sensitive ATPase activity associated with the plasma membrane of red beet storage tissue. The toxin had a very slight effect on the tonoplast ATPase and had no detectable effect on the mitochondrial ATPase. Optimal stimulation was achieved with 10 to 50 micrograms of syringomycin per 25 micrograms of membrane protein. Treatment of membranes with 0.1% (weight/volume) deoxycholate eliminated the activation effect, and enzyme solubilized with Zwittergent 3-14 was not affected by syringomycin. ATPase activity was activated to the same extent at KCl concentrations ranging from 0 to 50 millimolar. Valinomycin, nigericin, carbonylcyanidep-trifluoromethoxyphenylhydrazone, and gramicidin did not increase the plasma membrane ATPase activity. However, these ionophores did not hinder the ability of syringomycin to stimulate the activity. We suggest that syringomycin does not increase ATPase activity by altering membrane ion gradients nor directly interacting with the enzyme, but possibly through regulatory effectors or covalent modification of the enzyme.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB

摘要:

Mature-green tomato fruit (Lycopersicon esculentumMill.) were treated asymmetrically with 2 millimolar silver thiosulfate (STS) through a cut portion of the peduncle while still attached to the plant. One-half of the fruit received silver and remained green while the other half ripened normally and was silver-free (less than 0.01 parts per billion). Harvested mature-green fruit were also treated with STS through the cut pedicel. Green tissue from silver-treated fruit had levels of 1-aminocyclopropane-1-carboxylic acid (ACC, the immediate ethylene precursor) slightly less or similar to that of turning or red-ripe tissue from the same fruit, and similar to that of mature-green tissue from control fruit. Ethylene production was higher in green tissue from silver-treated fruit than from either red tissue from the same fruit, or mature-green tissue from control fruit. By inhibiting ACC synthesis with aminoethoxyvinyl glycine, and by applying ACC±silver to excised disks of pericarp tissue from control or silver-treated tomatoes, we showed that short-term silver treatment did not affect the biological conversion of ACC to ethylene, while long-term treatment stimulated both the conversion of ACC to ethylene and the synthesis of ACC

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1987

数据来源: ASPB