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  • Zea  (37)
  • Springer  (37)
  • International Union of Crystallography (IUCr)
  • Periodicals Archive Online (PAO)
  • 1980-1984  (37)
  • 1981  (22)
  • 1980  (15)
Collection
Keywords
Publisher
  • Springer  (37)
  • International Union of Crystallography (IUCr)
  • Periodicals Archive Online (PAO)
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  • 1980-1984  (37)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Enzymes of nitrogen assimilation in maize roots (1980)
    Springer
    Planta 148 (1980), S. 477-484 
    Details
    ISSN: 1432-2048
    Keywords: Enzymes ; Nitrogen assimilation ; Root ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The enzymes nitrate reductase (NR), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS) and asparagine synthetase (AS) have been assayed in various regions along the seedling root ofZea mays L. In the intact attached root and calculated on a protein basis NR, GOGAT, and GS are found to have slightly higher specific activities in the apical 5 mm than in more mature regions of the root. GDH and AS, on the other hand, are much more active in extracts prepared from mature regions of the root than in the apical region. In excised root tips incubated in the presence of NH4 + and NO3 − there was a marked increase in GDH and AS, and a slight decrease in GOGAT and GS. Additions of NO3 − are required for NR activity but neither NO3 − nor NH4 + additions altered the activity levels of the other four enzymes. Additions of glucose to the medium inhibited the development of AS and GDH activities and resulted in higher activity levels of NR, GS and GOGAT. Glucose additions also enhanced the incorporation of acetate-14C and leucine-14C into protein. Additions of cycloheximide inhibit the development of NR, AS and GDH activities and also the incorporation of acetate-14C and leucine into protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395318
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  • 2
    Electronic Resource
    Electronic Resource
    Auxin action on proton influx in corn roots and its correlation with growth (1980)
    Springer
    Planta 148 (1980), S. 510-512 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Cell wall pH ; Growth (roots) ; Proton flux and growth ; Root growth ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract At concentrations inhibitory to the elongation of corn (Zea mays L.) roots, the auxins, indole-3-acetic acid (IAA) and α-naphthaleneacetic acid (α-NAA), cause an increase in the pH of the bathing medium; this increase occurs with an average latent period shorter than the latent period for the inhibitory effect of these auxins on elongation. Indole-2-carboxylic acid, an inactive structural analogue of IAA, and β-naphthaleneacetic acid, an inactive analogue of α-NAA, affect neither growth nor the pH of the medium. Since acid pH is known to promote and basic pH to inhibit root elongation, the data are consistent with the hypothesis that hormone-induced modification of cell-wall pH plays a role in the control of elongation of roots, as has been proposed for elongation of stems and coleoptiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395322
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  • 3
    Electronic Resource
    Electronic Resource
    The phytochrome system in light-grown Zea mays L. (1980)
    Springer
    Planta 149 (1980), S. 91-96 
    Details
    ISSN: 1432-2048
    Keywords: Light-grown plants ; Phytochrome ; SAN 9789 ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phytochrome system is analyzed in light-grown maize (Zea mays L.) plants, which were prevented from greening by application of the herbicide SAN 9789. The dark kinetics of phytochrome are not different in the first, second or third leaf. It is concluded that in light-grown maize plants phytochrome levels are regulated by Pr formation and Pfr and Pr destruction, rather than by Pfr→Pr dark reversion. Pr undergoes destruction after it has been cycled through Pfr. The consequences of this Pr destruction on the phytochrome system are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386232
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  • 4
    Electronic Resource
    Electronic Resource
    Auxin uptake and action of N-1-naphthylphthalamic acid in corn coleoptiles (1981)
    Springer
    Planta 151 (1981), S. 15-25 
    Details
    ISSN: 1432-2048
    Keywords: Auxin (uptake, transport) ; Benzoic acid ; N-1-Naphthylphthalamic acid ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The validity of a chemiosmotic hypothesis for uptake of weak acids as an explanation for the accumulation of auxin by cells has been explored further by comparing the uptake of indole-3-acetic acid (IAA) by 1-mm segments of corn (Zea mays L.) coleoptiles with that of benzoic acid and two neutral indoles, indoleethanol and indoleacetonitrile, which do not ionize. These substances, while structurally related to IAA lack both auxin activity and polar transport. Uptake of IAA and benzoic acid increase with decreasing external pH, whereas the uptake of the two neutral indoles is independent of external pH. Although metabolism of IAA, during 90 min or less, is minimal and without significant effect on its uptake, metabolism of benzoic acid appears responsible for the apparent saturation of benzoic acid uptake at high concentrations. An inhibitor of auxin transport, N-1-naphthylphathalamic acid (NPA), stimulates uptake of IAA but has no effect on uptake of either benzoic acid or the two neutral indoles. Thus, NPA does not affect the driving forces for accumulation of weak acids but probably specifically decreases the flux of the auxin anions relative to undissociated auxin. Since the electrochemical potential of auxin anions is usually higher in than outside cells, blocking the anion flux with NPA would enhance auxin uptake. Azide, which abolishes accumulation of both IAA and benzoic acid, may simply collapse the pH gradient across the plasma membrane. In the absence of NPA, increasing concentrations of auxins or the analogoue β-naphthaleneacetic acid (β-NAA) exert two opposing effects on the uptake of IAA-depression and stimulation. Stimulation results from saturating the anion flux. With uptake fully stimulated by NPA, however, increasing concentrations of auxins or analogues only depress uptake of [3H]IAA. These results are consistent with more than one path for auxin transport each with a different dependence on concentration. In depressing NPA-stimulated IAA uptake, the effectiveness of β-NAA≧IAA≫α-NAA≫ benzoic acid, a specificity similar to that of an auxin binding site in vitro that has been implicated by others in auxin transport. The results support the general hypothesis that cellular auxin uptake and polar transport through tissues are chemiosmotically coupled to the electrochemical potential of auxin and protons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384232
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  • 5
    Electronic Resource
    Electronic Resource
    Isolation and characterization of aminopterin-resistant cell lines in maize (1981)
    Springer
    Planta 153 (1981), S. 436-442 
    Details
    ISSN: 1432-2048
    Keywords: Aminopterin-resistant variants ; Cell culture ; Folate analog ; Variant selection ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aminopterin-resistant cell lines of maize were isolated by two different procedures of callus selection and by plating suspension cultures on drugcontaining medium after mutagen treatment. Efficiencies of different methods of variant selection were compared. Four aminopterin-resistant cell lines were shown to be 10–40 times more resistant than the parental cell line, and they were also resistant to another folate analog, methotrexate. The results suggest that alterations in at least three different cell properties could be responsible for resistance; 1) increased dihydrofolate reductase activity, 2) altered aminopterin sensitivity of dihydrofolate reductase, and 3) reduced drug uptake. One of the resistant cell lines showed more than one alteration, but its resistance proved to be unstable. The results suggest that stable changes which may or may not be of genetic origin and also unstable physiological changes or a combination of both could lead to aminopterin resistance in maize cell cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394982
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of zearalenone (F-2) on pea stem, maize root, and rat liver mitochondria (1981)
    Springer
    Planta 153 (1981), S. 443-446 
    Details
    ISSN: 1432-2048
    Keywords: ATPase ; Mitochondria ; Mycotoxin ; Pisum ; Zea ; Zearalenone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract At 5 and 10 μg ml-1 concentration, zearalenone (F-2), a mycotoxin produced by a number of species of the genus Fusarium, causes an inhibition of the oxidative phosphorylation of isolated plant mitochondria, while at 20 and 40 μg ml-1 it causes uncoupling. However, when the mitochondria are pre-incubated for 20 min with F-2, the uncoupling appears to be the prevailing effect. F-2 is also able to inhibit the mitochondrial ATPase activity (Mg2+-dependent). Conversely, F-2 (40 μg ml-1) does not alter the ATP level of maize roots and only slightly affects the ATPase activity of pea stem and maize root microsomal fractions. In addition, F-2 (10–40 μg ml-1) inhibits ATP synthesis catalyzed by rat liver mitochondria. It is suggested that the phytotoxicity of F-2, also known for its ability to collapse the transmembrane electric potential of maize roots, may be mainly linked to its ability to increase the proton permeability of the cell, similar to the common uncouplers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394983
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  • 7
    Electronic Resource
    Electronic Resource
    Light-induced inhibitors from intact and cultured caps of Zea roots (1981)
    Springer
    Planta 153 (1981), S. 471-475 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid ; Geotropism (root) ; Growth inhibitor ; Light and root-cap inhibitor ; Root cap (inhibitor) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth inhibitors were assayed from extracts of intact (attached) and of excised (cultured) root caps of Zea mays L., cv. Merit, the roots of which show a positive geotropic response only after exposure to light. If caps are intact at the time of illumination, at least two inhibitory substances are produced, an acid inhibitor and a neutral inhibitor, whereas if caps are detached from roots, placed in culture and then illuminated only the neutral inhibitor is formed. Cycloheximide retards inhibitor production in both intact and cultured caps. When [14C]mevalonic acid is included in the culture medium and the caps are illuminated, 15–25% of the recoverable 14C cochromatographs with the neutral inhibitor, whereas in caps cultured in the dark, this radiolabelling pattern is not observed. Cyloheximide in the light reduces the incorporation of 14C into compounds cochromatographing at the Rf of the neutral inhibitor. It is suggested that the neutral inhibitor may be important in the light-induced bending of roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394989
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  • 8
    Electronic Resource
    Electronic Resource
    Levels of indole-3-acetic acid in intact and decapitated coleoptiles as determined by a specific and highly sensitive solid-phase enzyme immunoassay (1981)
    Springer
    Planta 153 (1981), S. 561-571 
    Details
    ISSN: 1432-2048
    Keywords: Auxin (immunoassay) ; Avena ; Coleoptiles (physiological tip) ; Enzyme immunoassay ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A specific solid-phase enzyme immunoassay for the detection of as little as 3–4 pg of indole-3-acetic acid (IAA) is described. The assay involves minimal procedural efforts and requires only standard laboratory equipment. Up to 50 samples in triplicate, processed simultaneously, can be assayed and evaluated in 2.5 h. As little as 1 mg oat coleoptile tissue is sufficient for a quantitative IAA analysis and little or no extract purification is necessary. Using this assay, levels of IAA have been determined in coleoptiles of maize and oat. The distribution of IAA within single coleoptiles was quantitated and the production of IAA during the regeneration of the physiological tip in Avena coleoptiles was investigated. The changes in levels of IAA and other major phytohormones were quantitated during the growth of oat coleoptiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385542
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  • 9
    Electronic Resource
    Electronic Resource
    Partial purification of endo- and exo-β-D-glucanase enzymes from Zea mays L. seedlings and their involvement in cell-wall autohydrolysis (1981)
    Springer
    Planta 151 (1981), S. 206-214 
    Details
    ISSN: 1432-2048
    Keywords: Cell-wall autohydrolysis ; β-D-Glucan ; Glucanase ; Hemicellulose ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The proteins dissociated from isolated Zea seedling cell wall using high-ionic-strength salt solutions have been found to include a number of enzymes which appear to participate in autolytic reactions of the cell wall. These enzymes caused extensive degradation of enzymatically inactive cell wall, liberating as much as 100 μg/mg dry weight over a 48-h period. Lithium chloride (3M) was shown to be most effective in yielding protein and wall-degrading activities. Molecular-sieve chromatography of the cell-wall protein resolved endo-β-D-glucanase and exo-β-1,3-glucanase (EC 3.2.1.58) activities when Avena glucan and laminarin, respectively, were employed as substrates. The exoenzyme (molecular weight around 60,000) was strongly inhibited by inorganic mercury at a concentration which suppressed the release of monosaccharide from autolytically active cell wall. The endo-β-D-glucanase (MW around 26,000), which showed a marked preference for substrates of mixed-linkage, exhibited features indicating that it initiates the autolytic solubilization of wall glucan. Cell-wall β-D-glucan, recovered as a component of an alkali-soluble cell-wall fraction, served as a substrate for the purified glucanases. Their hydrolysis pattern, assessed using gel exclusion chromatography and product analysis, confirmed that they hydrolyze β-D-glucan. The products generated by the endoglucanase were similar in molecular-size distribution to those liberated from autolytically active-wall. Exoglucanase activity was required for extensive hydrolysis of β-D-glucan in vitro. During coleoptile development the autolytic activity of the cell wall increased dramatically. This increased activity, however, did not parallel the growth potential of the tissue, but more closely reflected an increase in cell-wall β-D-glucan, the primary substrate for autolytic reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395171
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  • 10
    Electronic Resource
    Electronic Resource
    pH-Dependent accumulation of indoleacetic acid by corn coleoptile sections (1980)
    Springer
    Planta 147 (1980), S. 457-466 
    Details
    ISSN: 1432-2048
    Keywords: Auxin (transport, accumulation) ; Chemiosmotic hypothesis ; Coleoptile ; Transport (auxin) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The uptake of auxin by 1-mm slices of corn (Zea mays L.) coleoptiles, a tissue known to transport auxin polarly, depends on the pH of the medium. Short-term uptake of indole-3-acetic acid (IAA) in coleoptiles increases with decreasing pH of the buffer as would be expected if the undissociated weak acid, IAA·H, were more permeable than the auxin anion, IAA-, and IAA- accumulates in the tissues because of the higher pH of the cytoplasm. Although uptake of [3H]IAA is reduced in neutral buffers, it is greater than expected if it were limited to just the extracellular space of the tissue. The radioactivity accumulated by the tissue can be quantitatively extracted by organic solvents and identified as IAA by thin-layer chromatography. The tissue radioactivity is freely mobile and can efflux from the tissue. Thus these cells in pH 5 buffer are able to retain an average internal concentration of mobile IAA that is at least several times greater than the external concentration. A prominent feature of auxin uptake from acidic buffers is enhanced accumulation at high auxin concentration. This indicates that, in addition to fluxes of IAA·H, a saturable site is involved in auxin uptake. Whenever the auxin-anion gradient is directed outward, saturating the efflux of auxin anions increases accumulation. Furthermore, the observed slowing of short-term uptake of radioactive IAA by increasing concentrations of IAA or K+ indicates either an activation of the presumptive auxin leak or saturation of another carrier-mediated uptake system such as a symport of auxin anions with protons. By contrast in neutral buffers, effects of concentration on uptake rates disappear. This implies that at neutral pH the anion leak is decreased and influx depends on the symport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380188
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  • 11
    Electronic Resource
    Electronic Resource
    Acid growth effects in maize roots: Evidence for a link between auxin-economy and proton extrusion in the control of root growth (1981)
    Springer
    Planta 152 (1981), S. 285-291 
    Details
    ISSN: 1432-2048
    Keywords: Acid growth ; Auxin ; Growth ; Root ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of proton excretion in the growth of apical segments of maize roots has been examined. Growth is stimulated by acidic buffers and inhibited by neutral buffers. Organic buffers such as 2[N-morpholino] ethane sulphonic acid (MES) — 2-amino-2-(hydroxymethyl)propane-1,3 diol (Tris) are more effective than phosphate buffers in inhibiting growth. Fusicoccin(FC)-induced growth is also inhibited by neutral buffers. The antiauxins 4-chlorophenoxyisobutyric acid (PCIB) and 2-(naphthylmethylthio) propionic acid (NMSP) promote growth and H+-excretion over short time periods; this growth is also inhibited by neutral buffers. We conclude that growth of maize roots requires proton extrusion and that regulation of root growth by indol-3yl-acetic acid (IAA) may be mediated by control of this proton extrusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388251
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  • 12
    Electronic Resource
    Electronic Resource
    Small RNA species in maize tissue (1980)
    Springer
    Planta 150 (1980), S. 406-411 
    Details
    ISSN: 1432-2048
    Keywords: Maize tissue ; RNA metabolism ; Small RNA species ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The low molecular weight RNA components of maize have been analyzed after labeling callus and leaf tissue with [3H]uridine in vitro. Electrophoresis of the isolated RNA on acrylamide slab gels reveals, apart from 5S and transfer RNA, three major and about five minor RNA species with chain lengths between 140 and 280 nucleotides. These RNA molecules are labeled as rapidly as 5S, transfer RNA, and do not represent degradation products of large ribosomal RNA molecules. Furthermore, like 5S and transfer RNA, these small RNA species are stable and show no detectable turnover within forty-eight hours. Fractionation of the tissue into crude subcellular fractions indicates a preferential association of some of the small stable RNA species with the nucleus, while others appear to be located in the cytoplasm. The low molecular weight RNA spectrum from the leaf is similar to that observed in callus, with the major small RNA species equally present in both tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390177
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  • 13
    Electronic Resource
    Electronic Resource
    Effects of high temperature on the germination of maize (Zea mays L.) (1981)
    Springer
    Planta 151 (1981), S. 68-74 
    Details
    ISSN: 1432-2048
    Keywords: Energy metabolism ; Germination (seeds) ; Protein synthesis ; Temperature and seed germination ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Poor emergence of maize seedlings, due to high soil temperatures, is a major limitation of crop potential in the lowland tropics. Ability to germinate at high temperature (〉c. 37° C) is related to the temperature sensitivity of the embryo, and there is considerable genotypic variation for this character. Respiration and mitochondrial phosphorylation proceed normally in seeds imbibing at 41° C, and ATP levels are adequate for germination. However, the specific activities of several important enzymes are lower, and the rate of protein synthesis is severely reduced compared with seeds imbibing at 28° C. The depression of the rate of protein synthesis in the embryos of several tropical hybrids imbibing at high temperature correlated with their known temperature sensitivity. It is concluded that protein synthesis is an especially temperature sensitive process in germinating maize embryos, and that this is the principal reason for the sensitivity of germinating maize seeds to high temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384239
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  • 14
    Electronic Resource
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    Effects of high temperature on protein synthesis during germination of maize (Zea mays L.) (1981)
    Springer
    Planta 151 (1981), S. 75-80 
    Details
    ISSN: 1432-2048
    Keywords: Embryos (protein synthesis) ; Germination (seeds) ; Protein synthesis and temperature ; Temperature and protein synthesis ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The poor germination of maize seeds at high temperatures (〉37°C) is related to the low rate of protein synthesis by the embryo. The apparatus of translation was not heat-labile when embryos were incubated for 2 h at 41°C, and cell free extracts from seeds imbibed for 16 h at this temperature were able to translate exogenous mRNA, indicating that ribosomes and other subcellular components were present and functional. Analysis of polysome profiles from embryos imbibing at high temperature indicated that the low rate of protein synthesis was due to the non-availability of active mRNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384240
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  • 15
    Electronic Resource
    Electronic Resource
    Uptake of isolated plant chromosomes by plant protoplasts (1981)
    Springer
    Planta 151 (1981), S. 141-145 
    Details
    ISSN: 1432-2048
    Keywords: Chromosome isolation ; Petroselinum ; Polyethylene-glycol ; Protoplast (uptake of chromosomes) ; Triticum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For mass isolation of plant metaphase chromosomes, cultured cells of wheat (Triticum monococcum) and parsley (Petroselinum hortense) were synchronized by hydroxyurea and colchicine treatment. This synchronization procedure resulted in high mitotic synchrony, especially in suspension cultures of parsley in which 80% of the cells were found to be at the metaphase stage. Mitotic protoplasts isolated from these synchronized cell cultures served as a source for isolation of chromosomes. The described isolation and purification method yielded relatively pure chromosome suspension. The uptake of the isolated plant chromosomes into recipient wheat, parsley, and maize protoplasts was induced by polyethylene-glycol treatment. Cytological studies provided evidences for uptake of plant chromosomes into plant protoplasts.
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    URL: http://dx.doi.org/10.1007/BF00387815
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  • 16
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    Electronic Resource
    Differential growth of georeacting maize roots (1981)
    Springer
    Planta 151 (1981), S. 146-150 
    Details
    ISSN: 1432-2048
    Keywords: Georeaction (root) ; Growth inhibitors ; Growth (root) ; Root (georeaction, growth) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth rate of the two sides of 10-mm apical segments prepared from primary roots and of intact primary roots of maize has been analyzed in both vertical and horizontal positions, using a filming method allowing continuous growth recording. The data showed that the georeaction began by a decrease in the overall elongation rate of the roots. This inhibition is effective on the lower side of the bending zone, where the growth is practically stopped during the period of maximum rate of geocurvature. In contrast, the growth is slightly enhanced on the upper part of the elongating zone.
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    URL: http://dx.doi.org/10.1007/BF00387816
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  • 17
    Electronic Resource
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    In vitro binding of riboflavin to subcellular particles from maize coleoptiles and Cucurbita hypocotyls (1980)
    Springer
    Planta 147 (1980), S. 312-319 
    Details
    ISSN: 1432-2048
    Keywords: Cucurbita ; Endoplasmic reticulum ; Light (blue) receptor ; Plasmalemma ; Riboflavin binding ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Saturable and reversible in vitro binding of [14C]riboflavin was found to occur on subcellular, sedimentable particles from maize coleoptiles and Cucurbita hypocotyls. The KD was ca. 6 μM, the pH optimum was near 6.0, and the number of binding sites amounted to 0.1–0.5 μM on a fresh-weight basis. When the reducing agent dithionite was present, riboflavin binding increased-the KD was 2.5 μM, and the pH optimum above 8.0. The binding was specific: flavin mononucleotide (FMN) and flavin adenosine-dinucleotide (FAD) bound less tightly to these sites than riboflavin and another major soluble flavin, the previously described riboflavin-analog “FX”, occurring in grass coleoptiles. These flavin-binding sites were localized on vesicles derived from plasmalemma and endoplasmic reticulum by analyzing sucrose and metrizamide density gradients and marker enzymes.
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    URL: http://dx.doi.org/10.1007/BF00379839
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  • 18
    Electronic Resource
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    Daily changes in nitrate influx, efflux and metabolism in maize and pearl millet (1981)
    Springer
    Planta 152 (1981), S. 319-324 
    Details
    ISSN: 1432-2048
    Keywords: Nitrate influx (efflux, metabolism) ; Pennisetum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maize (Zea mays L.) and pearl millet (Pennisetum americanum (L.) Leeke) seedlings were exposed to [15N]nitrate for 1-h periods at eight times during a 24-h period (16–8 h light-dark for maize; 14–10 h for millet). Influx of [15N]nitrate as well as its reduction and translocation were determined during each period. The efflux of previously absorbed [14N]nitrate to the uptake solution was also estimated. No marked diurnal changes in [14N]nitrate efflux or [15N]nitrate influx were evident in maize. In contrast, [14N]nitrate efflux from millet increased and eventually exceeded [15N]nitrate influx during the late dark and early light periods, resulting in net nitrate efflux from the roots. The dissimilarity of their diurnal patterns indicates that influx and efflux are independently regulated. In both species, [15N]nitrate reduction and 15N translocation to shoots were curtailed more by darkness than was [15N]nitrate influx. In the light, maize reduced 15% and millet 24% of the incoming [15N]nitrate. In darkness, reduction dropped to 11 and 17%, respectively. Since the accumulation of reduced-15N in shoots declined abruptly in darkness, whereas that in roots was little affected, it is suggested that in darkness [15N]nitrate reduction occurred primarily in roots. The decrease in nitrate uptake and reduction in darkness was not related to efflux, which remained constant in maize and did not respond immediately to darkness in pearl millet.
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    URL: http://dx.doi.org/10.1007/BF00388256
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  • 19
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    Enzymes of nitrogen assimilation in maize roots (1980)
    Springer
    Planta 148 (1980), S. 477-484 
    Details
    ISSN: 1432-2048
    Keywords: Enzymes ; Nitrogen assimilation ; Root ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The enzymes nitrate reductase (NR), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS) and asparagine synthetase (AS) have been assayed in various regions along the seedling root ofZea mays L. In the intact attached root and calculated on a protein basis NR, GOGAT, and GS are found to have slightly higher specific activities in the apical 5 mm than in more mature regions of the root. GDH and AS, on the other hand, are much more active in extracts prepared from mature regions of the root than in the apical region. In excised root tips incubated in the presence of NH4 + and NO3 − there was a marked increase in GDH and AS, and a slight decrease in GOGAT and GS. Additions of NO3 − are required for NR activity but neither NO3 − nor NH4 + additions altered the activity levels of the other four enzymes. Additions of glucose to the medium inhibited the development of AS and GDH activities and resulted in higher activity levels of NR, GS and GOGAT. Glucose additions also enhanced the incorporation of acetate-14C and leucine-14C into protein. Additions of cycloheximide inhibit the development of NR, AS and GDH activities and also the incorporation of acetate-14C and leucine into protein.
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    Auxin action on proton influx in corn roots and its correlation with growth (1980)
    Springer
    Planta 148 (1980), S. 510-512 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Cell wall pH ; Growth (roots) ; Proton flux and growth ; Root growth ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract At concentrations inhibitory to the elongation of corn (Zea mays L.) roots, the auxins, indole-3-acetic acid (IAA) and α-naphthaleneacetic acid (α-NAA), cause an increase in the pH of the bathing medium; this increase occurs with an average latent period shorter than the latent period for the inhibitory effect of these auxins on elongation. Indole-2-carboxylic acid, an inactive structural analogue of IAA, and β-naphthaleneacetic acid, an inactive analogue of α-NAA, affect neither growth nor the pH of the medium. Since acid pH is known to promote and basic pH to inhibit root elongation, the data are consistent with the hypothesis that hormone-induced modification of cell-wall pH plays a role in the control of elongation of roots, as has been proposed for elongation of stems and coleoptiles.
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    URL: http://dx.doi.org/10.1007/BF00552667
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  • 21
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    Ca2+ transport in mitochondrial and microsomal fractions from higher plants (1980)
    Springer
    Planta 150 (1980), S. 1-8 
    Details
    ISSN: 1432-2048
    Keywords: Calcium uptake ; Microsomes ; Mitochondria ; Transport (Ca2+) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondria from etiolated corn possess a much greater Ca2+ uptake capacity per mg protein than microsomes from the same source. Differences in energy requirements, sensitivity to specific inhibitors, and sedimentation properties enabled us to study both Ca2+ uptake mechanisms without mutual contamination. The microsomal Ca2+ uptake does not vary much among different plants as compared to the mitochondrial Ca2+ uptake; this is also true for different organs of the same plant. Mitochondrial Ca2+ uptake is more dependent on the age of the seedlings than microsomal uptake, because of changes in active Ca2+ uptake activity rather than of changes in efflux. Intactness and the oxidative and phosphorylative properties of the mitochondria remained unchanged during this time period. Na+ and Mg2+ do not induce Ca2+ release from mitochondria.
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    Effect of indoleacetic acid, abscisic acid, root tips and coleoptile tips on growth and curvature of maize roots (1980)
    Springer
    Planta 150 (1980), S. 32-36 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic Acid ; Auxin ; Geotropism ; Root tip ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of externally applied indoleacetic acid (IAA) and abscisic acid (ABA) on the growth of roots of Zea mays L. was measured. Donor blocks of agar with IAA or ABA were placed laterally on the roots and root curvature was measured. When IAA was applied to vertical roots, a curvature directed toward the donor block was observed. This curvature corresponded to a growth inhibition at the side of the root where the donor was applied. When IAA was applied to horizontal roots from the upper side, normal geotropic downward bending was delayed or totally inhibited. The extent of retardation and the inhibition of curvature were found to depend on the concentration of IAA in the donor block. ABA neither induced curvature in vertical roots nor inhibited geotropic curvature in horizontal roots; thus the growth of roots was not inhibited by ABA. However, when, instead of donor blocks, root tips or coleoptile tips were placed onto vertical roots, a curvature of the roots was observed.
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  • 23
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    Energetics of the response of maize coleoptile tissue to indoleacetic acid (1981)
    Springer
    Planta 151 (1981), S. 499-505 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Calorimetry ; Coleoptile ; Energetics ; Growth regulator ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Indole-3-acetic acid (IAA) promotes an increase in steady-state heat production by corn (Zea mays L.) coleoptile tissue; this increase is associated with an elevation in aerobic respiration rates. A detailed time dependence of the exothermic response to IAA was obtained using flow calorimetry. The latent period and magnitude of response were evaluated as a function of IAA concentration and pH. The data indicate that more than one response may occur. The optimal change in heat production was produced by an IAA concentration of 3·10-5 M. It was initiated within 5 min after the start of the IAA treatment, and reached a magnitude in excess of 25% of the tissue's basal heat production. Concentrations of IAA greater than 1·10-4 M resulted in diminished response(s), but the effect was strongly pH dependent. Several possibilities for the increased heat production triggered by IAA are discussed.
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    A possible plasma membrane particle containing malic enzyme activity (1981)
    Springer
    Planta 151 (1981), S. 506-511 
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    ISSN: 1432-2048
    Keywords: Cell fractionation ; Cucurbita ; Malic enzyme ; Plasma membrane ; Subcellular localization ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A definite membrane fraction from Cucurbita hypocotyls, maize coleoptiles, and other plant tissues contains a NADP-dependent malic enzyme activity, up to 10% of overall tissue activity, and probably other soluble proteins. This “malic enzyme particle” is identified as plasmalemma on the basis of sedimentation behavior, density distribution in sucrose gradients, in comparison with enzyme markers, and sluggish penetration by the sugar Metrizamide. Enzyme binding to the plasma membrane is stable and scarcely sensitive to salts and EDTA, although all activity is released to the supernatant in the presence of Triton-X-100 or under hypotonic conditions. The properties of bound enzyme are similar to those of free enzyme in cell extracts. It is proposed that osmotically sensitive plasma membrane vesicles, containing cytoplasm fragments, are formed during homogenization. Low malic enzyme activities are also associated with Cucurbita proplastids.
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    Comparative analyses of the effect of triacontanol on photosynthesis, photorespiration and growth of tomato (C3-plant) and maize (C4-plant) (1981)
    Springer
    Planta 152 (1981), S. 44-49 
    Details
    ISSN: 1432-2048
    Keywords: Lycopersicon ; Phetorespiration ; Photosynthesis ; Triacontanol ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tomato (C3-plants) and maize (C4-plants) were grown in a nutrient solution to which triacontanol was added twice a week. After about 4 weeks the triacontanol treatment caused a significant increase in the dry weight of the tomato plants. Leaf area and dry weight measurements of tomato leaves at different stages of development showed that the largest increase in growth was obtained when triacontanol treatment was initiated before bud formation. In maize, no effect of the triacontanol treatment on dry wieght was observed. Photosynthesis was inhibited by 27% in young leaves from triacontanol-treated tomato plants and 39% in the controls, when the oxygen concentration was raised from 2% to 21%. In maize no change in photosynthesis could be observed, neither after altered oxygen concentration nor after triacontanol treatment. The difference in the response of C3- and C4-plants to triacontanol indicates that it regulates processes related to photosynthesis.
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    Extent of intracellular pH changes during H+ extrusion by maize root-tip cells (1981)
    Springer
    Planta 152 (1981), S. 74-78 
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    ISSN: 1432-2048
    Keywords: Cytoplasmic pH ; Fusicoccin ; Hydrogen-ion extrusion ; pH-stat ; Root ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 31P-Nuclear-magnetic-resonance spectra of maize (Zea mays L.) root tips, that had been induced to extrude large amounts of H+ in response to fusicoccin (FC) in the presence of potassium salts, indicate that the cytoplasmic pH does not become higher than that of controls. In fact, the cytoplasmic pH may become slightly (approx. 0.1 pH unit) lower in cells extruding H+. Estimations of the buffer capacity of the cells show that without active intracellular pH regulation, H+ extrusion caused by FC would cause the intracellular pH to rise by at least 0.6 pH unit h-1. Our results indicate that intracellular pH is tightly regulated even during extreme rates of acid extrusion, and that a rise in cytoplasmic pH is not the signal linking H+ extrusion with enhanced organic-acid synthesis or other intracellular responses to H+ pumping.
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    Correlations between proton-efflux patterns and growth patterns during geotropism and phototropism in maize and sunflower (1981)
    Springer
    Planta 152 (1981), S. 239-241 
    Details
    ISSN: 1432-2048
    Keywords: Acid growth ; Geotropism ; Helianthus ; Phototropism ; Proton secretion ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By placing seedlings of sunflower (Helianthus annuus L.) or maize (Zea mays L.) on agar plates containing a pH indicator dye it is possible to observe surface pH patterns along the growing seedling by observing color changes of the indicator dye. Using this method we find that in geotropically stimulated sunflower hypocotyls or maize coleoptiles there is enhanced proton efflux on the lower surface of the organ prior to the initiation of curvature. As curvature develops the pattern of differential acid efflux becomes more intense. A similar phenomenon is observed when these organs are exposed to unilateral illumination, i.e. enhanced acid efflux occurs on the dark side of the organ prior to the initiation of phototropic curvature and the pattern of differential acid efflux intensifies as phototropic curvature develops. These observations indicate that differential acid efflux occurs in response to tropistic stimuli and that the acid efflux pattern may mediate the development of tropistic curvatures.
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    Selection and characterization of a feedback-insensitive tissue culture of maize (1980)
    Springer
    Planta 148 (1980), S. 183-187 
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    ISSN: 1432-2048
    Keywords: Amino acids ; Feedback inhibition ; Mutant selection ; Tissue culture ; Variants, resistant ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tissue culture selection techniques were used to isolate a maize (Zea mays L.) variant D33, in which the aspartate family pathway was less sensitive to feedback inhibition by lysine. D33 was recovered by successively subculturing cultures originally derived from immature embryos on MS medium containing growth-inhibitory levels of lysine+threonine. The ability of D33 to grow vigorously on lysine+ threonine medium was retained after growth for 12 months on nonselection medium. New cultures initiated from shoot tissues of plants regenerated from D33 also were resistant to lysine+threonine inhibition. The Ki of aspartokinase for its feedback inhibitor, lysine, was about 9-fold higher in D33 than for the enzyme from unselected cultures. The free pools of lysine, threonine, isoleucine and methionine were increased 2–9-fold in D33 cultures. This was consistent with the observed change in feedback regulation of aspartokinase, the first enzyme common to the biosynthesis of these amino acids in the aspartate pathway. The accumulated evidence including the stability of resistance in the cultures, the resistance of cultures initiated from regenerated plants, the altered feedback regulation, and the increased free amino acids, indicates a mutational origin for these traits in line D33.
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    Fusicoccin receptors. Evidence for endogenous ligand (1980)
    Springer
    Planta 148 (1980), S. 208-210 
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    ISSN: 1432-2048
    Keywords: Endogenous ligands ; Fusicoccin ; Proton extrusion ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The binding of fusicoccin to the microsomal preparations of maize roots in vitro is increased several-fold when segments of the tissue are washed for 2 h in distilled water before homogenization. Addition of freeze-dried wash solution to microsomal preparations of spinach leaves or fresh roots, washed roots, or coleoptiles of maize inhibited the binding of fusicoccin to particulate fractions. The freeze-dried material also blocked fusicoccin-promoted H+ extrusion from maize root segments. Roots may contain one or more water-soluble compounds competing with fusicoccin at the receptor level; such ligands might play a physiological role as modulators of the H+/K+ exchange system in higher plants.
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    URL: http://dx.doi.org/10.1007/BF00380028
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    The action of specific inhibitors of auxin transport on uptake of auxin and binding of N-1-naphthylphthalamic acid to a membrane site in maize coleoptiles (1981)
    Springer
    Planta 152 (1981), S. 13-18 
    Details
    ISSN: 1432-2048
    Keywords: Auxin uptake ; Coleoptile ; Fluorescein ; Morphactin ; Naphthylphthalamic acid ; Triiodobenzoic acid ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using both 1-mm segments of corn (Zea mays L.) coleoptiles and a preparation of membranes isolated from the same source, we have compared the effectiveness of several inhibitors of geotropism and polar transport in stimulating uptake of auxin (indole-3-acetic acid, IAA) into the tissue and in competing with N-1-naphthylphthalamic acid (NPA) for a membrane-bound site. Low concentrations of 2,3,5-triiodobenzoic acid (TIBA), NPA, 2-chloro-9-hydroxyfluorene-9-carboxylic acid (morphactin), and fluorescein, eosin, and mercurochrome all stimulated net uptake of [3H]IAA by corn coleoptile tissues while higher concentrations reduced the uptake of both [3H]IAA and another lipophilic weak acid, [14C]benzoic acid. Since low concentrations of fluorescein and its derivatives competed for the same membrane-bound site in vitro as did morphactin and NPA, the basis for both the specific stimulation of auxin accumulation and the inhibition of polar auxin transport by all these compounds may be their ability to interfere with the carrier-mediated efflux of auxin anions from cells. At higher concentrations, the decrease in accumulation of weak acids was nonspecific and thus may be the result of acidification of the cytoplasm and a general decrease in the driving force for uptake of the weak acids. Triiodobenzoic acid was an exception. Low concentration of TIBA (0.1–1 μM) were much less effective than NPA in competing for the NPA receptor in vitro, but little different from NPA in ability to stimulate auxin uptake. One possibility is that TIBA, a substance which is polarly transported, may compete with auxin for the polar transport site while NPA, morphactin, and the fluorescein derivatives may render this site inactive.
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    Evidence for proteins specific for vascular elements in intact and cultured tissues and cells of maize (1980)
    Springer
    Planta 148 (1980), S. 116-123 
    Details
    ISSN: 1432-2048
    Keywords: Antigen ; Callus ; Cell suspension cultures ; Proteins (in differentiation) ; Seedling ; Vascular cylinder (stele) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A group of antigenically distinct proteins characteristic for the tissue complex of the vascular cylinders was found in maize (Zea mays L.) seedlings using an immunofiltration technique. Specific stelar antigens present in the fully developed stele (vascular cylinder) of the primary root were also found in steles extracted from adventitious roots and from the mesocotyl but were absent, within the limits of sensitivity of the immunodiffusion tests employed, in root cortex and epidermis. Some of the stelar antigens were also evident in the meristem of the primary root and were present in traces in the scutellum, the mesocotyl node, and the primary leaves plus coleoptile. The specific stelar antigens could be traced in 13- and 15-day-old developing embryos and were definitely expressed by the 21 st day after pollination. Several stelar-specific antigens were found in embryo-derived callus tissues and in stem-derived cells maintained in serial suspension culture. Higher resolution of the stelar antigens by a modified technique of crossed immunoelectrophoresis was used to demonstrate several minor stelar antigens that were presumably characteristic exclusively of the completely differentiated stele. This technique along with sequential immunoprecipitation of labelled proteins provided a semiquantitative estimate of the specific stelar antigens in the meristem and the stele of the primary root, and in suspension-cultured cells which were devoid of noticeable signs of vascular differentiation.
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    Rearrangement of enzyme patterns in maize callus and suspension cultures (1980)
    Springer
    Planta 148 (1980), S. 108-115 
    Details
    ISSN: 1432-2048
    Keywords: Callus ; Cell proliferation ; Cell suspension ; Coleoptile ; Cytodifferentiation ; Dedifferentiation ; Enzyme profile ; Internode ; Root tip ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of enzyme patterns was followed in the course of: (a) the irreversible cell differentiation via division and expansion to maturity in the root tip and coleoptile of the intact seedlings, (b) the irreversible cell dedifferentation associated with induction and establishment of callus from the growing internodes, and (c) the growth cycle (proliferation⇋stationary phase) in callus and cell-suspension cultures of maize (Zea mays L.). By measuring the activities of glycolytic, mitochondrial, microbody and hydrolytic enzymes cells proliferating in vivo and in vitro could be compared and changes related to cessation or resumption of cell division could be studied. Proliferating cells of callus and suspension cultures maintained by serial culture did not differ from those of the root meristem and coleoptile in the specific activities of hexokinase, phosphoglycerate kinase and phosphopyruvate hydratase. Proliferation in vitro resulted in an enormous increase in the ratio g glutamate-dehydrogenase/cytochrome-oxidase activity and in the level of acid-phosphatase activity, with concomitant drop in galactosidase and xylosidase activity. A 3-5-fold increase of alcohol-dehydrogenase, lactate-dehydrogenase and catalase activities was characteristic of dividing callus cells, while a ca. 100-fold increase in the fructofuranosidase-to-glucosidase activity ratio marked cell proliferation in suspension-cultured cells. Changing enzyme activities after cessation of proliferation were quite similar in root tips and coleoptiles, except those of alcohol dehydrogenase and catalase. The enzyme rearrangement during callus establishment and in the growth cycle of callus cultures was in most cases comparable to that in the intact tissues, while the changes from the dividing to the non-dividing cells in suspension cultures, in contrast, differed widely from those in the intact tissues and callus. Galactosidase and xylosidase were the only activities that showed a similar trend of changes in all the investigated, intact and in-vitro-grown cells. Thus, judged by the pattern of enzyme development, the cell suspension appears to be a unique system, virtually unrelated to the growing cells of the intact tissues. It is also very difficult to draw a definite distinction between the metabolic consequences of cell growth and enzyme modulations in cell suspensions as the cells adapt their metabolism to the environmental changes in liquid medium.
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    Low and high voltage electron microscopy of mitosis and cytokinesis in maize roots (1981)
    Springer
    Planta 152 (1981), S. 397-407 
    Details
    ISSN: 1432-2048
    Keywords: Cytokinesis ; High voltage electron microscopy ; Mitosis ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structure and distribution of cytoplasmic membranes during mitosis and cytokinesis in maize root tip meristematic cells was investigated by low and high voltage electron microscopy. The electron opacity of the nuclear envelope and endoplasmic reticulum (ER) was enhanced by staining the tissue in a mixture of zinc iodide and osmium tetroxide. Thin sections show the nuclear envelope to disassemble at prophase and become indistinguishable from the surrounding ER and polar aggregations of ER. In thick sections under the high voltage electron microscope the spindle is seen to be surrounded by a mass of tubular (TER) and cisternal (CER) endoplasmic reticulum derived from both the nuclear envelope and ER, which persists through metaphase and anaphase. At anaphase strands of TER traverse the spindle between the arms of the chromosomes. The octagonal nuclear pore complexes disappear by metaphase, but irregular-shaped pores persist in the membranes during mitosis. It is suggested that these form a template for pore-complex reformation during telophase. Phragmoplast formation is preceded by an aggregation of TER across the spindle at anaphase. Evidence is presented to suggest that the formation of the desmotubule of a plasmodesma is by the squeezing of a strand of endoplasmic reticulum between the vesicles of the cell plate.
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    Auxin binding in roots: A comparison between maize roots and coleoptiles (1981)
    Springer
    Planta 153 (1981), S. 447-452 
    Details
    ISSN: 1432-2048
    Keywords: Auxin binding ; Root (auxin) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Auxin binding onto membrane fractions of primary roots of maize seedlings has been demonstrated using naphth-1yl-acetic acid (NAA) and indol-3yl-acetic acid (IAA) as ligands. This binding is compared with the already well characterized interaction between auxins and coleoptile membranes. The results indicate that while kinetic parameters are of the same order for root and coleoptile binding, a number of differences occur with respect to location in cells and relative affinity. The possible significance of the existence of such binding sites in root cells is discussed in relation to auxin action.
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    Abscisic acid distribution in horizontal maize root segments (1981)
    Springer
    Planta 153 (1981), S. 453-458 
    Details
    ISSN: 1432-2048
    Keywords: Abscisic acid ; Gravireaction ; Growth inhibitors ; Root ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using gas chromatography-mass spectrometry (GC/MS) techniques of analyses, it has been found that endogenous abscisic acid (ABA) becomes asymmetrically distributed in the elongation zone of horizontal Zea mays (cv. LG 11) roots which are showing a positive gravitropic response. There is a relative increase in the ABA content of the lower half and a concomitant decrease for the upper half in such roots. Asymmetric distribution of ABA is also detected in the elongation zone of half-decapped roots.
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    Patterns of polypeptide synthesis in various maize organs under anaerobiosis (1980)
    Springer
    Planta 150 (1980), S. 89-94 
    Details
    ISSN: 1432-2048
    Keywords: Anaerobiosis ; Protein synthesis, organspecific ; Stress ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pattern of protein synthesis was compared in several organs of maize (Zea mays L.) under aerobic and anaerobic conditions. Protein synthesis was measured by [35S]methionine incorporation and analysis by two-dimensional native-SDS (sodium lauryl sulfate) polyacrylamide gel electrophoresis and fluorography. The aerobic protein-synthesis profiles were very different for root, endosperm, scutellum and anther wall. However, except for some characteristic qualitative and quantitative differences, the patterns of protein synthesis during anaerobiosis were remarkably similar for these diverse organs and also for mesocotyl and coleoptile. The proteins synthesized were the anaerobic polypeptides (ANPs) which have been previously described in anaerobic roots of seedlings. Leaves exhibited no detectable protein synthesis under anaerobic conditions, and died after a short anaerobic treatment. Evidence is presented that the ANPs are not a generalized response to stress. This indicates that the ANPs are synthesized as a specific response to anaerobic conditions such as flooding.
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    Inhibition by silver ions of gas space (aerenchyma) formation in adventitious roots of Zea mays L. subjected to exogenous ethylene or to oxygen deficiency (1981)
    Springer
    Planta 153 (1981), S. 217-224 
    Details
    ISSN: 1432-2048
    Keywords: Aerenchyma ; Ethylene ; Gas space ; Oxygen and gas-space formation ; Roots, adventitious ; Silver ions ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the role of ethylene in accelerating the lytic formation of gas spaces (aerenchyma) in the cortex of adventitious roots of maize (Zea mays L.) growing in poorly aerated conditions. Such roots had previously been shown to contain increased concentrations of ethylene. Ten day-old maize plants bearing seminal roots and one whorl of emerging adventitious roots were grown in nutrient solution bubbled with air, ethylene in air (0.1 to 5.0 μl l−1), or allowed to become oxygen-deficient in nonaerated (but not completely anaerobic) solution. Additions of 0.1 μl l−1 ethylene or more promoted the formation of aerenchyma, with lysis of up to 47% of the cortical cells. The effects of non-aeration were similar to those of exogenous ethylene. When silver ions, an ethylene antagonist, were present at low, non-toxic concentrations (circa 0.6 μM), aerenchyma formation was prevented in ethylene treated roots and in those exposed to oxygen deficiency. Silver ions also blocked the inhibiting effect of exogenous ethylene on root extension. By contrast, the suppression of aerenchyma formation by silver ions under oxygendeficient conditions was associated with a retardation of root extension, indicating the importance of aerenchyma for root growth in poorly aerated media. Rates of production of ethylene by excised roots were stimulated by a previous non-aeration treatment. The effectiveness of Ag+ in inhibiting equally the action on cortical cells of exogenous ethylene and of non-aeration, supports the view that gas space (aerenchyma) formation in adventitious roots ‘adpted’ to oxygendeficient environments is mediated by increased concentrations of endogenous ethylene. The possibility that extra ethylene could arise from increased biosynthesis of a precursor in root tissues with a restricted oxygen supply is discussed.
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    URL: http://dx.doi.org/10.1007/BF00383890
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