Plant Physiology

Dean, Bill B.

doi: 10.1104/pp.89.4.1021pmid: 16666655

Abstract The effect of temperature on suberization of potato tuber tissue was measured by diffusive resistance and quantitative chemical procedures. The optimum temperature for formation of aliphatic suberin monomers and development of resistance to water vapor conduction was 26.4°C whereas alkane synthesis was optimal at 18.6°C. Low temperatures (<16.6°C) reduced suberin monomer production more than alkane synthesis. 1 This work was supported by the Washington State Department of Agriculture through the IMPACT Center Project No. 4933. Hort/LA Paper No. 88-27. College of Agriculture and Home Economics Research Center, Washington State University, Pullman, WA 99164. This content is only available as a PDF. © 1989 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)

Ngernprasirtsiri, Jarunya; Takabe, Tetsuko; Akazawa, Takashi

doi: 10.1104/pp.89.4.1024pmid: 16666656

Abstract Pure preparations of intact amyloplasts and chloroplasts, free from mitochondrial contamination, were isolated from cultured cells of the white-wild and green-mutant lines of sycamore (Acer pseudoplatanus L.), respectively. A specific rabbit antiserum against yeast mitochondrial cytochrome c 1 only cross-reacted with mitochondrial membranes from the white-wild sycamore cells. The outer and inner envelope-membranes of the two plastid-types were isolated and subsequently analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis to characterize polypeptide patterns in each fraction. Analysis by immunoblotting clearly showed that antiserum against the 29-kilodalton inorganic orthophosphate translocator isolated from pea chloroplasts cross-reacted with a 31-kilodalton polypeptide residing in the inner-envelope membranes from both sycamore chloroplasts and amyloplasts. In contrast, antiserum against the ADP/ATP-translocator isolated from mitochondria of Neurospora crassa yielded a positive signal with a 32-kilodalton polypeptide in the inner-membranes isolated from amyloplasts, but not green-mutant chloroplasts. We propose that this 32-kilodalton polypeptide in the amyloplast envelope is a putative ATP/ADP-translocator and its possible functional significance is discussed. 2 Recipient of a predoctoral student fellowship provided by the Hitachi Scholarship Foundation (Tokyo). Permanent address: Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10500, Thailand. 1 This is Paper No. 79 in the series “Structure and Function of Chloroplast Proteins.” This research was supported in part by research grants from the Ministry of Education, Science and Culture (Mombusho) of Japan and the Nissan Science Foundation (Tokyo). This content is only available as a PDF. © 1989 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)

Rise, Moshe; Cojocaru, Miriam; Gottlieb, Hugo E.; Goldschmidt, Eliezer E.

doi: 10.1104/pp.89.4.1028pmid: 16666657

Abstract α-Tocopherol (α-T) has been identified, using gas chromatography-mass spectroscopy and 1H- and 13C-nuclear magnetic resonance, in senescing leaves of Melia azedarach L. The content of α-T increased concomitantly with the breakdown of chlorophyll in senescing Vinca and Melia leaves. An increase in α-T was found also in detached Melia leaves, senescing in either light or darkness and in senescing, ethylene-treated orange leaves and fruit. The possibility that phytol, which is released from chlorophyll by chlorophyllase is utilized for the biosynthesis of α-T is discussed. Senescing leaves of the low chlorophyllase plants, parsley and tobacco, did not contain α-T in measureable amounts. This content is only available as a PDF. © 1989 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)

Rajashekar, C. B.

doi: 10.1104/pp.89.4.1031pmid: 16666658

Abstract The amount of unfrozen water in dormant peach (Prunus persica [L.] Batsch, cv Redhaven) flower buds, isolated primordia, and bud axes was determined during freezing using pulse nuclear magnetic resonance methods. Differential thermal analysis studies were conducted on whole buds and isolated primordia in the presence of ice nucleation. The results showed that some of the water in isolated primordia remained supercooled in the presence of ice nucleation. Although most tissue water froze (57.5%) following ice nucleation at −2.5°C, a considerable amount of water was found to supercool. In the presence of ice nucleation, increased hydration of isolated primordia resulted in the elimination of the supercooling characteristic. The structural integrity of isolated primordia appeared to be essential for supercooling. 1 Supported partially by the U.S. Department of Agriculture grant 86-CRCR-1-2065 and Kansas Agricultural Experiment Station (Contribution No. 88-500-J) This content is only available as a PDF. © 1989 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)

Chen, Pei-Chung; Almon, Helmar; Böger, Peter

doi: 10.1104/pp.89.4.1035pmid: 16666659

Abstract Four species of nitrogen-fixing heterocystous cyanobacteria were compared with respect to induction of hydrogenase activity. Two of the strains contained phycoerythrin and built up high levels of carbohydrate storage material when grown in batch culture under nitrogen-fixing conditions and continuous illumination. These strains did not exhibit hydrogenase activity. Lack of activity in the phycoerythrin-containing species was determined by cell-free assays measuring both hydrogen-evolving and hydrogen-uptake activities. Apparently, expression of hydrogenase is negatively correlated with the carbohydrate pool present and concurrent respiration. Furthermore, there is an apparent relationship between the presence of phycoerythrin, carbohydrate accumulation, and the absence of hydrogenase activity. 2 Permanent Address: Department of Botany, National Chung-Hsing University, Taichung, Taiwan 400, Republic of China. 3 Present address: Michigan State University, MSU-DOE Plant Research Laboratory, East Lansing, MI 48824. 1 Supported by the Zentrum für Energieforschung of this University and by the Deutsche Forschungsgemeinschaft (Sonderforschungsbereich No. 248). This content is only available as a PDF. © 1989 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)

Gage, Douglas A.; Fong, Franklin; Zeevaart, Jan A. D.

doi: 10.1104/pp.89.4.1039pmid: 16666660

Abstract Previous labeling experiments with 18O2 have supported the hypothesis that stress-induced abscisic acid (ABA) is synthesized through an indirect pathway involving an oxygenated carotenoid (xanthophyll) as a precursor. To investigate ABA formation under nonstress conditions, an 18O2 labeling experiment was conducted with isolated embryos from in vitro grown maize (Zea mays L.) kernels. Of the ABA produced during the incubation in 18O2, three-fourths contained a single 18O atom located in the carboxyl group. Approximately one-fourth of the ABA synthesized during the experiment contained two 18O atoms. These results suggest that ABA synthesized in maize embryos under nonstress conditions also proceeds via the indirect pathway, requiring a xanthophyll precursor. It was also found that the newly synthesized ABA was preferentially released into the surrounding medium. 2 Present address: Michigan State University-National Institutes of Health Mass Spectrometry Facility, Department of Biochemistry, Michigan State University, East Lansing, MI 48824. 1 Supported by the United States Department of Energy under contract DE-AC02-76ERO-1338 and the National Science Foundation through grants PCM 83-14321 (to J.A.D.Z.) and PCM 8402572 (to J. D. Smith, F. Fong, and C. W. Magill). This content is only available as a PDF. © 1989 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)

Doehlert, Douglas C.

doi: 10.1104/pp.89.4.1042pmid: 16666661

Abstract Four forms of hexose kinase activity from developing maize (Zea mays L.) kernels have been separated by ammonium sulfate precipitation, gel filtration chromatography, blue-agarose chromatography, and ion exchange chromatography. Two of these hexose kinases utilized d-glucose most effectively and are classified as glucokinases (EC 2.7.1.2). The other two hexose kinases utilized only d-fructose and are classified as fructokinases (EC 2.7.1.4). All hexose kinases analyzed had broad pH optima between 7.5 and 9.5 with optimal activity at pH 8.5. The two glucokinases differed in substrate affinities. One form had low K m values [K m(glucose) = 117 micromolar, K m(ATP) = 66 micromolar] whereas the other form had much higher K m values [K m(glucose) = 750 micromolar, K m(ATP) = 182 micromolar]. Both fructokinases had similar substrate saturation responses. The K m(fructose) was about 130 micromolar and the K m(ATP) was about 700 micromolar. Both exhibited uncompetitive substrate inhibition by fructose [K i(fructose) = 1.40 to 2.00 millimolar]. ADP inhibited all four hexose kinase activities, whereas sugar phosphates had little effect on their activities. The data suggest that substrate concentrations are an important factor controlling hexose kinase activity in situ. This content is only available as a PDF. © 1989 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)

Takeshige, Kazuhiko; Tazawa, Masashi

doi: 10.1104/pp.89.4.1049pmid: 16666662

Abstract The cytoplasm and the vacuole were isolated from internodal cells of Chara corallina by using the intracellular perfusion technique, and their buffer capacities (βi) were determined from the titration curves. The pH of the isolated vacuolar sap was 5.19 ± 0.029 (mean ± standard error). At this pH, βi was minimal and amounted to 0.933 ± 0.11 millimoles H+/pH unit/liter vacuolar sap. The pH of isolated cytoplasm was 7.22 ± 0.028. βi was minimal in this pH region and amounted to 14.2 ± 0.80 millimoles H+/pH unit/liter cytoplasm. When 1% (volume/volume) Triton X-100 was added to the cytoplasmic solution to permeabilize the subcellular organelles, the cytoplasmic pH increased to 7.32 ± 0.026, where βi was 20.35 ± 2.66 millimoles H+/pH unit/liter cytoplasm. This shows that alkaline subcellular compartments exist in the cytoplasm and also that the cytoplasmic pH before adding Triton X-100 may represent the cytosolic pH. These data indicate that the pH values of the cytoplasm and the vacuole are regulated at the values where the βi values are minimal. This suggests that ATP- and inorganic pyrophosphate-dependent H+ pumps in the plasma membrane and the tonoplast could efficiently regulate the pH of both cytoplasm and vacuole in Chara internodal cells. 1 Supported by a grant-in-aid for scientific research from the Ministry of Education, Science and Culture and by a grant-in-aid for special project research (No. 60223011) from Coordination Funds for the Promotion of Science and Technology from the Science and Technology Agency of Japan. This content is only available as a PDF. © 1989 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)

Shih, Ching Yu; Dumbroff, Erwin B.; Thompson, John E.

doi: 10.1104/pp.89.4.1053pmid: 16666663

Abstract During cell-free experiments with membranes isolated from carnation petals (Dianthus caryophillus L. cv White Sim), the conversion of 1-aminocyclopropane-1-carboxylic acid into ethylene was blocked by a factor derived from the cytosol. Subsequent characterization of the inhibitor revealed that its effect was concentration dependent, that it was water soluble, and that it could be removed from solution by dialysis and addition of polyvinyl-polypyrrolidone. Activity profiles obtained after solvent partitioning over a range of pH values and after chromatography on silica gel, size exclusion gel, and ion exchange resins revealed that the inhibitor was a highly polar, low molecular weight species that was nonionic at low pH and anionic at pH values above 8. Use of selected solvent systems during paper and thin layer chromatography combined with specific spray reagents tentatively identified the compound as a hydroxycinnamic acid derivative. Base hydrolysis and subsequent comparison with known standards by high performance liquid chromatography, gas-liquid chromatography, and ultraviolet light spectroscopy established that the inhibitor was a conjugate with a ferulic acid moiety. Release of ferulic acid following treatment with β-glucosidase also indicated the presence of a glucose moiety, and unequivocal identification of the inhibitor as 1-O-feruloyl-β-d-glucose was confirmed by gas chromatography-mass spectroscopy and by ultraviolet light, 1H-, and 13C- nuclear magnetic resonance spectroscopy. Feruloylglucose constituted about 0.1% of the dry weight of stage III (preclimacteric) carnation petals, but concentrations fell sharply during stage IV (climacteric), when ethylene production peaks and the flowers senesce. In a reaction mixture containing microsome-bound ethylene forming enzyme system, 98% of all ethylene production was abolished in the presence of 50 μm concentrations of the inhibitor. 2 Present address: Department of Biochemistry and Biophysics, University of California, Davis, Davis, CA 95616. 3 Present address: Department of Horticultural Science, University of Guelph, Guelph, Ontario, N1G 2W2, Canada. 1 Supported by grants from the Natural Sciences and Engineering Research Council of Canada. This content is only available as a PDF. © 1989 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)

Sharkey, Thomas D.; Seemann, Jeffrey R.

doi: 10.1104/pp.89.4.1060pmid: 16666664

Abstract We have examined the effect of mild water stress on photosynthetic chloroplast reactions of intact Phaseolus vulgaris leaves by measuring two parameters of ribulose bisphosphate (RuBP) carboxylase activity and the pool sizes of RuBP, 3-phosphoglycerate (PGA), triose phosphates, hexose monophosphates, and ATP. We also tested for patchy stomatal closure by feeding 14CO2. The k cat of RuBP carboxylase (moles CO2 fixed per mole enzyme per second) which could be measured after incubating the enzyme with CO2 and Mg2+ was unchanged by water stress. The ratio of activity before and after incubation with CO2 and Mg2+ (the carbamylation state) was slightly reduced by severe stress but not by mild stress. Likewise, the concentration of RuBP was slightly reduced by severe stress but not by mild stress. The concentration of PGA was markedly reduced by both mild and severe water stress. The concentration of triose phosphates did not decline as much as PGA. We found that photosynthesis in water stressed leaves occurred in patches. The patchiness of photosynthesis during water stress may lead to an underestimation of the effect of stomatal closure. We conclude that reductions in whole leaf photosynthesis caused by mild water stress are primarily the result of stomatal closure and that there is no indication of damage to chloroplast reactions. 1 Research supported by U.S. Department of Energy grants DE-FG02-87ER13785 and DE-FG02-87ER60568 to T. D. S. and by U.S. Department of Agriculture Competitive Research Grants Office grant CRCR-1-2470 to J. R. S. This content is only available as a PDF. © 1989 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)