Plant Physiology

Labavitch, John M.; Ray, Peter M.

doi: 10.1104/pp.53.5.669pmid: 16658765

Abstract Turnover of cell wall polysaccharides and effects of auxin thereon were examined after prelabeling polysaccharides by feeding pea (Pisum sativum var. Alaska) stem segments 14C-glucose, then keeping the tissue 7 hours in unlabeled glucose with or without indoleacetic acid. There followed an extraction, hydrolysis, and chromatography procedure by which labeled monosaccharides and uronic acids were released and separated with consistently high recovery. Most wall polymers, including galacturonan and cellulose, did not undergo appreciable turnover. About 20% turnover of starch, which normally contaminates cell wall preparations but which was removed by a preliminary step in this procedure, occurred in 7 hours. Quantitatively, the principal wall polymer turnover process observed was a 50% decrease in galactose in the pectinase-extractable fraction, including galactose attached to a pectinase-resistant rhamnogalacturonan. Other pectinase-resistant galactan(s) did not undergo turnover. No turnover was observed in arabinans, but a doubling of radioactivity in arabinose of the pectinase-resistant, hot-acid-degradable fraction occurred in 7 hours, possibly indicating conversion of galactan into arabinan. None of the above changes was affected by indoleacetic acid, but a quantitatively minor turnover of a pectinase-degradable xyloglucan was found to be consistently promoted by indole-acetic acid. This was accompanied by a reciprocal increase in water-soluble xyloglucan, suggesting that indoleacetic acid induces conversion of wall xyloglucan from insoluble to water-soluble form. The results indicate a highly selective pattern of wall turnover processes with an even more specific influence of auxin. 2 Present address: Department of Chemistry, University of Colorado, Boulder, Colorado 80302 1 Research was supported by grants to P. M. R. from the National Science Foundation. This content is only available as a PDF. © 1974 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)

Beitler, Gene A.; Hendrix, John E.

doi: 10.1104/pp.53.5.674pmid: 16658766

Abstract It was hypothesized that stachyose is translocated by squash because stachyose is supplied to the phloem loading system by the photosynthetic system. To test this hypothesis, 14CO2 was supplied to squash leaves. The nonphosphorylated sugars containing 14C were studied. A large proportion of 14C appeared in stachyose very early in the time sequence, tending to confirm the hypothesis. 1 This work was supported by National Science Foundation Grant GB-14773 and Colorado State University Grant FIC 752. This content is only available as a PDF. © 1974 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)

Pring, D. R.

doi: 10.1104/pp.53.5.677pmid: 16658767

Abstract Mitochondria were prepared from etiolated maize shoots (Zea mays L. var. McNair 508) by homogenization followed by differential centrifugation and equilibrium banding in discontinuous sucrose or Renografin-sucrose gradients. Mitochondria prepared by sucrose banding showed better physiological integrity than those prepared by renografin-sucrose banding, although both procedures yielded mitochondria that showed respiratory control and coupling of oxidation to phosphorylation of ADP. Mitochondria prepared by Renografin-sucrose banding were free of dectectable cytoplasmic ribosomal RNA, while sucrose banding resulted in a low level of contamination. Ribosomes isolated from mitochondria sedimented at about 78S, with subunits sedimenting at 60 and 44S. Using Escherichia coli ribosomal RNA as internal standards, the molecular weights of mitochondrial ribosomal RNAs were found to be 0.74 to 0.75 and 1.26 × 106 daltons by polyacrylamide gel electrophoresis, before or after denaturation in formaldehyde. Cytoplasmic ribosomal RNA molecular weights were 0.70 and 1.26 × 166 before denaturation, and 0.68 and 1.5 × 106 after denaturation, suggesting an unusual reaction of the heavy ribosomal RNA to formaldehyde. 1 Cooperative Investigation, Agricultural Research Service, United States Department of Agriculture, and Institute of Food and Agricultural Sciences, University of Florida. Florida Agricultural Experiment Stations Journal Series No. 5006. This content is only available as a PDF. © 1974 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)

Albersheim, Peter; Valent, Barbara S.

doi: 10.1104/pp.53.5.684pmid: 16658768

Abstract The results presented demonstrate that microbial pathogens of plants have the ability to secrete proteins which effectively inhibit an enzyme synthesized by the host; an enzyme whose substrate is a constituent of the cell wall of the pathogen. The system in which this was discovered is the anthracnose-causing fungal pathogen (Colletotrichum lindemuthianum) and its host, the French bean (Phaseolus vulgaris). An endo-β-1, 3-glucanase present in the bean leaves is specifically inhibited by a protein secreted by C. lindemuthianum. The cell walls of C. lindemuthianum are shown to be composed largely of a 1, 3-glucan. 2 To whom correspondence should be addressed. 1 Research was supported in part by a grant from the Herman Frasch Foundation and by Atomic Energy Commission Contract AT(11-1)-1426. This content is only available as a PDF. © 1974 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)

Schrader, L. E.; Cataldo, D. A.; Peterson, D. M.

doi: 10.1104/pp.53.5.688pmid: 16658769

Abstract The in vitro instability of nitrate reductase (EC 1.6.6.1) activity from leaves of several species of higher plants was investigated. Decay of activity was exponential with time, suggesting that an enzyme-catalyzed reaction was involved. The rate of decay of nitrate reductase activity increased as leaf age increased in all species studied. Activity was relatively stable in certain genotypes of Zea mays L., but extremely unstable in others. In all genotypes of Avena sativa L. and Nicotiana tabacum L. studied, nitrate reductase was unstable. Addition of 3% (w/v) bovine serum albumin or casein to extraction media prevented or retarded the decay of nitrate reductase activity for several hours. In addition, the presence of bovine serum albumin or casein in the enzyme homogenate markedly increased nitrate reductase activity (up to 15-fold), especially in older leaf tissue. 1 This research was supported by the College of Agricultural and Life Sciences, University of Wisconsin-Madison, and by United States Department of Agriculture Cooperative Agreement 12-14-100-10,888. This content is only available as a PDF. © 1974 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)

Wara-Aswapati, Onnop; Bradbeer, J. W.

doi: 10.1104/pp.53.5.691pmid: 16658770

Abstract At concentrations of up to 300 μg/ml both d-threo- and l-threo-chloramphenicol act as energy transfer inhibitors in spinach chloroplasts, in that they inhibit both phosphorylation and phosphorylating electron transport, without affecting the nonphosphorylating electron transport which occurs either in the absence of a phosphate acceptor or in the presence of the uncoupler ammonium chloride. At higher concentrations, there appears to be an additional site of chloramphenicol inhibition of electron transport. If d-threo-chloramphenicol is to be used as a protein synthesis inhibitor in intact chloroplasts or tissues, control experiments with another chloramphenicol isomer seem to be necessary. 2 Present address: Department of Biology, Chiengmai University, Chiengmai, Thailand. 3 To whom correspondence should be addressed. 1 This work was supported by a Colombo Plan Scholarship to O. W-A. This content is only available as a PDF. © 1974 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)

Yang, Jiu-Sherng; Brown, Gregory N.

doi: 10.1104/pp.53.5.694pmid: 16658771

Abstract Total aminoacylation of glycine and leucine transfer RNAs was compared between chilled and nonchilled hypocotyls of 7-day-old soybean seedlings. Total charging was greater for both specific transfer RNAs from nonchilled sources. Isoaccepting transfer RNA species for glycine and leucine were fractionated using reverse phase column chromatography. Leucyltransfer RNAs were fractionated into six distinct fractions with relatively small shifts appearing in specific fractions between chilled and nonchilled sources. Glycyl-transfer RNAs were fractionated into two distinct fractions with major shifts appearing for both fractions between chilled and nonchilled sources. 3 Present address: No. 15, Lane 4, Shyh-Yuan Rd., Gou Tzyy Koo, Taipei, 116, Taiwan. 1 This investigation was supported in part by National Science Foundation Grant GB 8692. 2 Contribution from the Missouri Agricultural Experiment Station; Journal Series No. 6775. This content is only available as a PDF. © 1974 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)

Anderson, Mark M.; McCarty, Richard E.; Zimmer, Elizabeth A.

doi: 10.1104/pp.53.5.699pmid: 16658772

Abstract A galactolipid lipase has been isolated and partially purified from the chloroplast fraction of the primary leaves of Phaseolus vulgaris var. Kentucky Wonder. The lipase hydrolyzed monogalactosyl diglyceride rapidly and phosphatidyl choline relatively slowly. Triolein and p-nitrophenyl stearate were not hydrolyzed. Spinach subchloroplast particles were excellent substrates for the lipase. Initial rates of fatty acid release from subchloroplast particles at 30 C by the lipase as high as 60 microequivalents per minute per milligram protein were observed. At completion of the reaction, about 2.7 microequivalents of fatty acid were liberated per milligram of chlorophyll in the subchloroplast particles, indicating that major amounts of lipid in the particles were rapidly attacked by the lipase. The treatment of subchloroplast particles with the lipase resulted in a rapid inhibition of light-dependent electron flow. This inhibition was largely prevented when the incubation was carried out in the presence of high concentrations of defatted bovine serum albumin. These results suggest that when precautions are taken to prevent the binding of fatty acids to the subchloroplast particles, large amounts of lipid may be removed without a marked effect on electron flow. 3 Present Address: Department of Bio-organic Chemistry, Research Laboratories, Albert Einstein Medical Center, York and Tabor Roads, Philadelphia, Pennsylvania 19141. 1 This work was supported by National Institute of Health Predoctoral Training Grant 5T GM 00824-10 to M. M. A., by Research Grant GB-30597X from the National Science Foundation, and by Research Career Development Award GM-14,877 to R. E. M. 2 This material is from a dissertation submitted by M. M. A. to the Graduate School of Cornell University in partial fulfillment of the requirements of the degree of doctor of philosophy. This content is only available as a PDF. © 1974 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)

Finkle, Bernard J.; Pereira, E. Sa B.; Brown, M. S.

doi: 10.1104/pp.53.5.705pmid: 16658773

Abstract Small cylinders of red beet (Beta vulgaris) root were frozen at various rates. Ultraslow cooling at 0.2 C per hour to −4 C produced little damage, as determined by leakage of pigment and electrolytes, and softening. All of these increased at faster rates of cooling or at lower temperatures. Cooling at the ultraslow rate appears to induce extracellular freezing, resulting in a protective dehydration of the cell contents. 1 This work was partially supported by the American Frozen Food Institute. 2 Portions of the content of this article were communicated to the XIII International Congress of Refrigeration (5). 3 Portions of this work were submitted in partial fulfillment of the requirements for the degree of Master of Science in Food Science, University of California, Berkeley, by E. Sa B. P. This content is only available as a PDF. © 1974 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)

Brown, M. S.; Pereira, E. Sa B.; Finkle, Bernard J.

doi: 10.1104/pp.53.5.709pmid: 16658774

Abstract Temperature recordings of the freezing of plant tissues include two plateaus or regions of reduced slope. During the second of these, small positive spikes were observed. When a completely frozen tissue was thawed and refrozen, neither the second plateau nor the spikes were recorded. Both were present, however, if the initial freezing had been terminated before the second plateau had been reached. The spikes appear to represent the release of heat of crystallization during the freezing of individual cells. Such a freezing and thawing cycle destroys the ability of the cells to remain supercooled in the presence of the ice that is formed as the first plateau is recorded. 1 This work was partially supported by the American Frozen Food Institute. 2 Portions of the content of this article were communicated to the XIII International Congress of Refrigeration (3). 3 Portions of this work were submitted in partial fulfillment of the requirements for the degree of Master of Science in Food Science, University of California, Berkeley, by E. Sa B. P. This content is only available as a PDF. © 1974 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)