Plant Physiology

Ball, Marilyn C.; Mehlhorn, Rolf J.; Terry, Norman; Packer, Lester

doi: 10.1104/pp.78.1.1pmid: 16664179

Abstract Measurement of intrathylakoid aqueous volumes by electron spin resonance spectroscopy was used to study ionic permeability properties of thylakoid membranes isolated from Beta vulgaris L. and Avicennia germinans L. The thylakoids behaved as perfect osmometers in the presence of sorbitol and betaine. Thylakoids exposed to hypertonic solutions of NaCl and KCl shrank and subsequently swelled, requiring 10 minutes to regain their original volume. The initial influx rate calculated from the kinetics of changes in intrathylakoid volume in response to 450 millimolar gradients of NaCl and KCl was 2.3 × 10−13 moles per square centimeter per second. These data show that the passive permeability to NaCl and KCl was low. 2 Current address: Department of Biogeography and Geomorphology, Research School of Pacific Studies, P.O. Box 4, Australian National University, Canberra, A.C.T. 2601 Australia. 1 Supported by the University of California, Kearney Foundation of Soil Science, and the Office of Biological Energy Research, Division of Basic Energy Sciences, United States Department of Energy. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Delhaize, Emmanuel; Loneragan, Jack F.; Webb, John

doi: 10.1104/pp.78.1.4pmid: 16664204

Abstract Subterranean clover (Trifolium subterraneum L. cv Seaton Park) was grown in solution cultures containing adequate nitrogen both with and without Cu. After Cu deficiency had developed, Cu2+ was added to some deficient plants and Cu content, protein content, and activities of three Cu metalloenzymes (diamine oxidase [EC1.4.3.6], ascorbate oxidase [EC1.10.3.3] and o-diphenol oxidase [EC1.10.3.1]) were assayed in young and recently matured leaf blades over 11 days during the development of the next three leaves. Copper deficiency had little effect on protein concentrations, but markedly depressed enzyme activities and Cu concentration in all leaf blades assayed. Within 4 d of adding Cu2+ to Cu-deficient plants, Cu concentrations of all the leaf blades increased to adequate values. Enzyme activities only increased to control levels in leaves which had not yet emerged at the time that Cu2+ was added. The results suggest that active holoenzymes of diamine oxidase, ascorbate oxidase, and o-diphenol oxidase can only be synthesized in leaf blades during very early stages of their development. 2 School of Mathematical and Physical Sciences, Murdoch University, Perth, Western Australia 6150. 1 Supported by the Australian Wool Corporation on the advice of the Production Research Advisory Committee. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Metzger, James D.

doi: 10.1104/pp.78.1.8pmid: 16664213

Abstract Field pennycress (Thlaspi arvense L.) is a winter annual that requires a cold treatment for the induction of stem elongation. An inbred line was selected in which no stem elongation was observed in plants grown for 6 months at 21°C regardless of the prevailing photoperiod. Increased exposure time of plants grown initially at 21°C to cold (2°C) induced a greater rate of stem elongation when the plants were returned to 21°C. Moreover, longer cold treatments resulted in a greater maximum stem height and reduced the lag period for the onset of measurable internode elongation. The optimal temperature range for thermoinduced stem growth was broad: rates of stem growth in plants maintained for 4 weeks at either 2° or 10°C were virtually identical. However, a 4-week thermoinductive treatment at 15°C resulted in a greater lag period for the initiation of stem elongation and a decreased growth rate. The rate of cold-induced stem elongation was greater in plants subjected to long days than for plants subjected to short days following the cold treatment. Thus, photoperiod does not control the induction of stem elongation, but does regulate stem elongation in progress. Exogenous gibberellin A3 (GA3) was able to substitute for the cold requirement, but elicited a greater response in plants maintained under long days than short days. This indicates that photoperiod influences the plant's sensitivity to GAs. The GA biosynthesis inhibitor, 2-chloroethyltrimethyl ammonium chloride, inhibited low temperature-induced stem elongation, and this inhibition was completely reversed by exogenous GA3. These results suggest that cold-induced stem elongation in field pennycress is mediated by some change in the endogenous GA status. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Cosio, Eric G.; Weissenböck, Gottfried; McClure, Jerry W.

doi: 10.1104/pp.78.1.14pmid: 16664187

Abstract Mature soybean (Glycine max L. cv Harosoy 63) leaves normally contain kaempferol-3-glycosides but they accumulate no other flavonoids. Whole leaves sprayed with the diphenyl ether herbicide Acifluorfen and maintained in the light developed small necrotic lesions and accumulated isoflavone aglycones, isoflavone glucosides, and pterocarpans. Isoflavonoid accumulation was preceded by induced activity for chalcone synthase (CHS) and by increased activity for phenylalanine ammonia-lyase (PAL) and UDP-glucose:isoflavone 7-O-glucosyl transferase (IGT). PAL and CHS activity was highest between 24 and 30 hours after treatment, isoflavone aglycones and pterocarpans at 48 hours, IGT at 72 hours, and isoflavone glucosides at 96 hours. Mesophyll cells isolated from control leaves contained no activity for PAL, CHS, or IGT and no flavonoids of any class. Cells isolated from treated leaves at the stage of maximal enzyme activity or isoflavonoid content contained PAL (12% of the whole leaf activity), CHS (24%), IGT (20%), and 25% of the whole leaf isoflavone glucosides, but only traces, presumably as contaminants, of the other flavonoids. We suggest that the isoflavone glucosides were synthesized and accumulated in intact mesophyll cells as soluble detoxification products, while the isoflavone aglycones and pterocarpans accumulated in the epidermis or extracellularly within the mesophyll. To our knowledge this is the first report of tissue-specific induction of isoflavonoid glucosides and key enzymes of their biosynthesis in any plant. 2 Supported by a Fulbright-Hays Travel Grant, and by a Fellowship from the Heinrich Hertz Stiftung from the Ministry of Science and Research of Northrine-Westfalia. Present address: Department of Botany, University of British Columbia, Vancouver, B.C. V6T 2B1, Canada. 1 Supported in part by grant WE 630/9-5 from the Deutsche Forshungsgemeinschaft to G.W., and by a Miami University Faculty Research Committee Award to J.W.Mc. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Kato, Yoji; Nevins, Donald J.

doi: 10.1104/pp.78.1.20pmid: 16664198

Abstract A small quantity of (1→3)-β-d-glucan was extracted with a (1→3),(1→4)-β-d-glucan by hot water after treatment of the insoluble fraction of a buffer homogenate of Zea shoots with 3 molar LiCl. An ammonium sulfate precipitation procedure effected a separation of the (1→3)-β-d-glucan from the more prevalent (1→3),(1→4)-β-d-glucan. The minor component polysaccharide precipitated at a concentration of 20% ammonium sulfate (w/v) and was, as a consequence of precipitation, rendered insoluble in water. The insoluble products were dissolved in 1 normal NaOH followed by neutralization with CH3COOH. The purified polysaccharide accounted for approximately 0.3% of total hot water extract. It consisted mostly of glucose and its average mol wt was estimated to be about 7.0 × 104, based on elution from a calibrated Sepharose CL-4B column. Methylation analysis and enzymic hydrolysis or partial acid-hydrolysis of the polysaccharide followed by analysis of the hydrolysate showed that the polysaccharide consisted of (1→3)-β-linked glucose residues. 2 Present address: Department of Agricultural Chemistry, Faculty of Agriculture, Tohoku University, Sendai, Miyagi 980, Japan. 3 Present address: Department of Vegetable Crops, University of California, Davis, CA 95616. 1 Supported in part by National Science Foundation Research Grant PCM 7818588. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Muhitch, Michael J.; Fletcher, John S.

doi: 10.1104/pp.78.1.25pmid: 16664201

Abstract The influence of cell age on phenol accumulation was examined by determining the quantity of individual phenols which accumulated in Paul's scarlet rose cultures of increasing age. During log-phase growth (days 7 and 11), only gallic acid and epicatechin-catechin were detected; whereas, during early and late stationary phase (days 14 and 35), several other phenols were present in addition to gallic acid and epicatechincatechin. When stationary-phase cultures were provided with a supplement of sucrose and spermidine, a treatment previously shown to arrest the senescence of rose cultures (Muhitch, Edwards, Fletcher 1983 Plant Cell Rep 2: 82-84), the cells then accumulated a higher level and a wider assortment of phenols. These results suggest that extending the lifespan of mature nondividing cell cultures offers a means of increasing the yield of secondary products by cultured cells. 2 Present address: American Cyanamid Co., Agricultural Research Division, P.O. Box 400, Princeton, NJ 08540. 1 Supported by National Institute of Health Grant 5 R01 AGJ0170903. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Giridhar, G.; Thimann, Kenneth V.

doi: 10.1104/pp.78.1.29pmid: 16664202

Abstract A study was made of the influence of wounding on the senescence of standard oat leaf segments in the dark. Wounding was by either subdividing the 3 centimeter long segments into 5 millimeter subsegments, gently scraping the adaxial surface of the segments with a sharp blade, making transverse linear cuts, or by making many small holes with a needle. Wounding considerably delayed the loss of both chlorophyll and protein in the dark and the amount of inhibition was roughly proportional to the intensity of wounding. With surface wounding, the inhibition of senescence was detectable from the first day of dark incubation; other methods caused moderate promotion of senescence for the first 2 days but decreased the loss of chlorophyll and protein thereafter. A number of senescence-modifying substances acted similarly on both unwounded and wounded segments, but the amount of chlorophyll and protein in the wounded segments was always more than in the respective controls. Cytokinins, however, provided an exception, since their effect was actually decreased by wounding. The proteases operating at pH 4.1 and 6.6 were both clearly less active in the wounded leaves than in controls. The possible mechanism of this inhibitory effect of wounding on senescence is discussed. 2 Present address: AREC, 18905 S. W. 280th Street, Homestead, FL 33031. 1 Supported in part by a grant from the National Science Foundation to K. V. T. (No. PCM 80-21584). This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Carroll, Bernard J.; McNeil, David L.; Gresshoff, Peter M.

doi: 10.1104/pp.78.1.34pmid: 16664203

Abstract The nodulation characteristics of soybean (Glycine max) mutant nts382 are described. The mutant nodulated significantly more than the parent cultivar Bragg in the presence and absence of several combined nitrogen sources (KNO3, urea, NH4Cl, and NH4NO3). The number of nodules on the tap root and on lateral roots was increased in the mutant line. In the presence of KNO3 and urea, nitrogenase activity was considerably higher in nts382 than in Bragg. Mutant plants were generally smaller than wild-type plants. Although nts382 is a supernodulator, inoculation with Rhizobium japonicum was necessary to induce nodule formation and both trial strains CB1809 (= USDA136) and USDA110 elicited the mutant phenotype. Segregation of M3 progeny derived from a M2 wild-type plant indicated that the mutant character is inherited as a Mendelian recessive. The mutant is discussed in the context of regulation of nodulation and of hypotheses that have been proposed to explain nitrate inhibition of nodulation. 2 Present address: Western Australia Department of Agriculture, Kununurra Research Station, Kununurra, Western Australia, Australia. 1 Supported by an Agrigenetics sponsored research program and an Australian Government Postgraduate Award to B. J. Carroll. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Lin, Willy

doi: 10.1104/pp.78.1.41pmid: 16664205

Abstract The accumulation of tetraphenylphosphonium (TPP+), 5,5′-dimethyl-oxazolidine-2,4-dione (DMO), and a micro pH electrode were used to measure membrane potential, intracellular and extracellular pH, respectively, upon the addition of exogenous sucrose to soybean cotyledon protoplasts. Addition of sucrose caused a specific and transient (a) depolarization of the membrane potential (measured by TPP+ accumulation), (b) acidification of the intracellular pH (measured by DMO accumulation), and (c) alkalization of the external medium (measured by a micro pH electrode). The time course for all these changes was similar (i.e. 5 to 10 minutes). Based on the rate of sucrose uptake and alkalization of the external medium, a stoichiometry of 1.02 to 1.10 for proton to sucrose was estimated. These data strongly support a proton/sucrose cotransporting mechanism in soybean cotyledon cells. 1 Contribution No. 3525 from Central Research and Development Department, Experimental Station, E. I. du Pont de Nemours and Company, Wilmington, DE 19898. This paper is dedicated to Professor John B. Hanson on the occasion of his retirement. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Ensminger, Michael P.; Hess, F. Dan

doi: 10.1104/pp.78.1.46pmid: 16664206

Abstract Photosynthesis is not required for the toxicity of diphenyl ether herbicides, nor are chloroplast thylakoids the primary site of diphenyl ether herbicide activity. Isolated spinach (Spinacia oleracea L.) chloroplast fragments produced malonyl dialdehyde, indicating lipid peroxidation, when paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) or diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] were added to the medium, but no malonyl dialdehyde was produced when chloroplast fragments were treated with the methyl ester of acifluorfen (methyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid), oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene], or MC15608 (methyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-chlorobenzoate). In most cases the toxicity of acifluorfen-methyl, oxyfluorfen, or MC15608 to the unicellular green alga Chlamydomonas eugametos (Moewus) did not decrease after simultaneous treatment with diuron. However, diuron significantly reduced cell death after paraquat treatment at all but the highest paraquat concentration tested (0.1 millimolar). These data indicate electron transport of photosynthesis is not serving the same function for diphenyl ether herbicides as for paraquat. Additional evidence for differential action of paraquat was obtained from the superoxide scavenger copper penicillamine (copper complex of 2-amino-3-mercapto-3-methylbutanoic acid). Copper penicillamine eliminated paraquat toxicity in cucumber (Cucumis sativus L.) cotyledons but did not reduce diphenyl ether herbicide toxicity. 2 Present address: Stauffer Chemical Company, Mountain View, CA 94042. 1 Journal Paper no. 10,093 of the Purdue University Agricultural Experiment Station. This content is only available as a PDF. © 1985 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)