Plant Physiology

Adams, Clifford A.; Novellie, Lawrence

doi: 10.1104/pp.55.1.1pmid: 16659009

Abstract Protein bodies and spherosomes have been isolated from mature seeds of Sorghum bicolor (Linn.) Moench by a procedure which successfully disrupts the protein starch complex in the grain. Protein bodies from whole grain are 68% protein and have a distinct border and a monolithic appearance. Those from embryo are 95% protein and have diffuse borders, vacuoles, and appear very granular. Aleurone tissue protein bodies are 46% protein with a structure similar to those from embryo, but possibly are composed of a protein carbohydrate mixture. Spherosomes from all sources are quite similar in composition and structure. They have an average composition of 27% protein, 12% phosphorus, and 8.6% metals. Microscopically, they appear as small vesicles bounded by a wall which is probably composed of protein and the potassiummagnesium salt of phytic acid. This content is only available as a PDF. © 1975 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)

Adams, Clifford A.; Novellie, Lawrence

doi: 10.1104/pp.55.1.7pmid: 16659031

Abstract Protein bodies and spherosomes isolated from mature seeds of Sorghum bicolor (Linn.) Moench have measurable activity of acid protease, α-glucosidase, β-glucosidase, β-galactosidase, phytase, acid pyrophosphatase, p-nitrophenyl phosphatase, and RNase. Protein bodies have largely insoluble activities, and produce soluble protein and soluble amino nitrogen during autolysis. They have the dual function of protein storage and protein catabolism. Spherosomes have considerable amounts of soluble enzymes and autolytically produce soluble amino nitrogen and inorganic phosphate but release little soluble protein. Spherosomes are similar to animal lysosomes but have an additional storage function for protein, phosphorus, and metals. Mature sorghum seed contains the necessary enzymes and substrates to generate two basic metabolites, amino acids and inorganic phosphate. This content is only available as a PDF. © 1975 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)

Robinson, J. Michael; Latzko, Erwin; Gibbs, Martin

doi: 10.1104/pp.55.1.12pmid: 16659015

Abstract Disalicylidenepropanediamine (DSPD) at 0.1 to 1 mm levels inhibited light-dependent 14CO2 assimilation in intact spinach chloroplasts about 50 to 80%, and this inhibition was accompanied by an increased ratio of 14C-glycerate 3-phosphate to 14C-glyceraldehyde 3-phosphate. Enzymatic analysis established that DSPD also inhibited the light-dependent reduction of glycerate 3-phosphate in intact spinach chloroplasts. DSPD at 0.5 mm did not inhibit ribose 5-phosphate isomerase, ribulose 5-phosphate kinase, glycerate 3-phosphate kinase, NADP+-linked glyceraldehyde 3-phosphate dehydrogenase or ribulose 1,5-diphosphate carboxylase. The inhibition of chloroplast 14CO2 assimilation by DSPD appeared to be related to the inhibition of the photosynthetic electron transport chain. These observations are consistent with experimental results which demonstrated that DSPD inhibited directly the chloroplast lamellar membrane-mediated, light-dependent reduction of ferredoxin (Trebst, A. and M. Burba, 1967, Z. Pflanzenphysiol. 57: 419-433 and Ben-Amotz, A. and M. Avron, 1972, Plant Physiol. 49: 244-248). 2 National Institute of Health Trainee, Grant GM-1586-07. 3 Permanent address: Institut für Chemie und Landwirtscharftl. Technologie, 805 Weihenstephan, West Germany. 1 This research was supported by United States Atomic Energy Commission Grant AT 11-1 (3231). This content is only available as a PDF. © 1975 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)

Frederick, Paula E.; Heath, Robert L.

doi: 10.1104/pp.55.1.15pmid: 16659020

Abstract Ozone-treated cells of the photosynthetic green alga Chlorella sorokiniana var. pacificensis exhibit an exponential decline in viability, as measured by their ability to form colonies on agar plates. Postexposure conditions appear to have little, if any, effect on this rate of decline. Except in young (early exponential phase) cells, culture age did not affect this rate. The decline in cell viability was correlated with the production of malondialdehyde, arising from the oxidative breakdown of an ozonide of unsaturated fatty acid material. The loss of fatty acids is substantiated by gas-liquid chromatography. A loss of 5 × 10-15 moles of fatty acid per cell corresponds to 75% nonviable cells after 50 minutes of ozone exposure. 1 This project has been financed in part with federal funds from the Environmental Protection Agency under Grant No. 801311. 2 The contents do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. This content is only available as a PDF. © 1975 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)

Mexal, John; Fisher, James T.; Osteryoung, Janet; Reid, C. P. Patrick

doi: 10.1104/pp.55.1.20pmid: 16659021

Abstract The solubility of O2 in polyethylene glycol 4000 and 6000 solutions of varying concentrations was determined iodimetrically (titrimetrically) and electrochemically using a rotating glassy carbon electrode and a PAR Model 174 Polarograph. The titrimetric determination resulted in the formation of an unexpected precipitate at 2% (w/v) polyethylene glycol corresponding to the approximate critical micelle concentration of the two polyethylene glycol homologs. Beyond 5% polyethylene glycol, O2 concentration was inversely proportional to polyethylene glycol concentration, and was higher in polyethylene glycol 4000 solutions than in polyethylene glycol 6000. The electrochemical data are a direct measure of O2 transport to the electrode surface, rather than O2 activity or concentration. Results indicate that even at relatively high H2O potentials, the transport of O2 to the root surface might be insufficient to meet the plant's respiratory requirements. 2 Present address: Southern Forestry Research Center, Weyerhauser Company, Hot Springs, Ark. 71901. 3 Departments of Civil Engineering and Microbiology. 1 This research was supported by National Science Foundation Grant GB-19928 and by a grant from the Pacific Northwest Forest and Range Experiment Station, Forest Service, United States Department of Agriculture. This content is only available as a PDF. © 1975 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)

Hogsett, William E.; Quatrano, Ralph S.

doi: 10.1104/pp.55.1.25pmid: 16659022

Abstract Beginning 10 hours after fertilization, zygotes of Fucus distichus L. Powell incorporate 35S into polysaccharides as a sulfate ester of fucose. These sulfated polysaccharides are sequestered in only the rhizoid cell of the two-celled embryo and can serve as a marker of cellular differentiation. Zygotes were pulsed at different times after fertilization with Na235SO4 to identify and isolate the fucans localized within the region of cytoplasm destined to become the rhizoid cell. Low molecular weight pools of 35S were saturated within 60 minutes, with the greatest incorporation into ethanol-soluble and insoluble fractions occurring with 0.1 mm Na2SO4 in the artificial sea water medium. At the time of rhizoid formation, four fucose-containing polysaccharide fractions incorporated 35S. When each fraction was subjected to diethylaminoethyl chromatography, two components were eluted with KCl that contained over 84% of the fucose and 93% of the 35S of the particular fraction. Highvoltage paper electrophoresis of each fraction also resulted in the separation of these two major components. Both components from each of the four fractions behaved identically when separated by diethylaminoethyl chromatography and paper electrophoresis. By comparing the incorporation of 35S into the polysaccharide fractions at 4 and 16 hours after fertilization, the fucan-sulfate components that are localized in the cytoplasm at the time of rhizoid formation were isolated. Although sulfated polysaccharides in brown algae are reported to be very heterogeneous in terms of their sugar composition and complexes with other heteropolymers, we propose that there are two major components that are sulfated during early embryogenesis in Fucus. The location of these two sulfated polysaccharides in different chemical fractions may reflect their subcellular localization (e.g., cytoplasmic vesicles or cell walls), or their association with other heteropolymers. 1 This investigation was supported by Research Grant GM 19247 from the United States Public Health Service to R. S. Q. This content is only available as a PDF. © 1975 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)

Davis, Barry; Merrett, Michael J.

doi: 10.1104/pp.55.1.30pmid: 16659023

Abstract The development of glycolate pathway enzymes has been determined in relation to photosynthetic competence during the regreening of Euglena cultures. Phosphoglycolate phosphatase and glycolate dehydrogenase rapidly reached maximal levels of activity but the complete development of ribulose 1,5-diphosphate carboxylase and concomitant photosynthetic carbon dioxide fixation were not attained until 72 hours of illumination. Specific inhibitors of protein synthesis showed that the formation of ribulose 1,5-diphosphate carboxylase in both division-synchronized and regreening cultures was prevented by both cycloheximide and d-threo-chloramphenicol, whereas phosphoglycolate phosphatase formation was only inhibited by d-threo-chloramphenicol but not by l-threo-chloramphenicol or cycloheximide. Since cycloheximide prevented ribulose diphosphate carboxylase synthesis and photosynthetic carbon dioxide fixation without affecting phosphoglycolate phosphatase synthesis during regreening, it was concluded that photosynthetic competence was not necessary for the development of the glycolate pathway enzymes. The inhibition of phosphoglycolate phosphatase synthesis by d-threo-chloramphenicol but not by l-threo-chloramphenicol or cycloheximide shows that the enzyme was synthesized exclusively on chloroplast ribosomes, whereas protein synthesis on both chloroplast and cytoplasmic ribosomes was required for the formation of ribulose 1,5-diphosphate carboxylase. Although light is required for the development of both Calvin cycle and glycolate pathway enzymes during regreening it is concluded that the two pathways are not coordinately regulated. This content is only available as a PDF. © 1975 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)

Miller, Richard W.; Sirois, J.-Claude; Morita, Hirokazu

doi: 10.1104/pp.55.1.35pmid: 16659024

Abstract The peroxidase catalyzed oxidation of indole-3-acetate is inhibited by naturally occurring coumarins such as scopoletin. This inhibition is due to the preferential reactivity of the coumarins with the peroxidase compounds I, II, and III. In view of the possible growth regulatory role of coumarins in plants, the mechanism of oxidation of scopoletin by horse-radish peroxidase has been investigated. Peroxidase catalyzed coumarin oxidation requires either an electron donor and molecular oxygen or hydrogen peroxide. If peroxide is present, the reaction is mediated by peroxidase compound II which reacts rapidly and stoichiometrically with scopoletin. Different oxidation products are formed, depending on whether IAA or hydrogen peroxide promotes the reaction. A scopoletin-free radical intermediate has been isolated from the peroxide reaction mixture but was not detected in the peroxide-free system. When indole-3-acetate is the electron donor, reduced peroxidase combines with molecular oxygen to give peroxidase compound III. Added scopoletin is cooxidized with indole-3-acetate. Compared to the scopoletin peroxidation, this reaction is slower and yields fewer coumarin oxidation products. The differences observed between the two scopoletin oxidation pathways reflect: (a) the competition between indole-3-acetate and scopoletin for peroxidase compounds; (b) the lower reactivity of scopoletin with peroxidase compound III compared with peroxidase compound II. The peroxide-promoted reaction is eliminated by catalase, while the indole-3-acetate initiated oxidation is not affected by excess quantities of either catalase or superoxidase dismutase. 1 Contribution No. 789, Chemistry and Biology Research Institute; Contribution No. 483, Soil Research Institute. This content is only available as a PDF. © 1975 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)

Reeve, David R.; Crozier, Alan; Durley, Richard C.; Reid, David M.; Pharis, Richard P.

doi: 10.1104/pp.55.1.42pmid: 16659025

Abstract [3H]-Gibberellin A1 (GA1) and 3H-GA4 were applied separately to Phaseolus coccineus seedlings grown under red light. 3H-GA1 was converted to a compound with gas-liquid radiochromatography retention times identical to those of GA8. 3H-GA4 underwent conversion to at least three metabolites, none of which corresponded to GA1-38. The rate of metabolism of 3H-GA4 was significantly higher than that of 3H-GA1. 1 Supported by a Science Research Council (United Kingdom) grant. 2 Supported by National Research Council (Canada) Grant A-5727. 3 Supported by National Research Council (Canada) Grant A-2585. This content is only available as a PDF. © 1975 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)

Salminen, Seppo O.; Young, Roy E.

doi: 10.1104/pp.55.1.45pmid: 16659026

Abstract Glucose 6-phosphate, fructose 6-phosphate, fructose 1, 6-diphosphate, and triose phosphates, and the enzymes phosphofructokinase, aldolase, and glucose 6-phosphate dehydrogenase were extracted from banana fruit (Musa cavendishii, Lambert var. Valery) at the (a) preclimacteric, (b) climacteric rise, (c) climacteric peak, and (d) postclimacteric stages of ripening. The level of fructose 1, 6-diphosphate increased 20-fold whereas the concentration of other intermediates changed no more than 2.5-fold between stages a and c. For these same extracts, phosphofructokinase activity increased 2.5-fold whereas the activity of glucose 6-phosphate dehydrogenase and aldolase changed only fractionally. Substrate saturation studies (fructose 6-phosphate) of phosphofructokinase activity showed a decrease in the [S]0.5 from 5.6 to 1.7 mM betwen stages a and c. The enzyme from both sources seems to be regulated by a negative cooperative effect with the control being more stringent in the enzyme from stage a. The difference in enzyme activity is consistent with the increase in respiratory activity between the two stages. 1 Present address: Department of Plant Science, The University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2. This content is only available as a PDF. © 1975 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)