Plant Physiology

Michel, Burlyn E.

doi: 10.1104/pp.48.5.513pmid: 16657829

Abstract Stirring largely eliminated the greater effectiveness of Carbowax 6000 compared to mannitol in reducing cucumber (Cucumis sativus L.) hypocotyl section elongation. Stirring increased elongation in water but reduced elongation in growth regulator solution. Shrinkage of cells without plasmolysis in hypertonic Carbowax solutions indicates that Carbowax 6000 did not penetrate cell walls. Sections prevented from elongating during pretreatment exposure to saturated air grew as much as those not pretreated. Sections pretreated with isotonic Carbowax responded similarly, but sections pretreated with isotonic mannitol grew less. This content is only available as a PDF. © 1971 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)

Wu, M. T.; Singh, B.; Salunkhe, D. K.

doi: 10.1104/pp.48.5.517pmid: 16657830

Abstract Foliar applications of 2 milligrams per liter of 2-chloro-4,6-bis (ethylamino)-s-triazine, 2-methylmercapto-4-ethylamino-6-isobutylamino-s-triazine, and 2-methoxy-4-isopropylamino-6-butylamino-s-triazine caused increases in the activities of starch phosphorylase, pyruvate kinase, cytochrome oxidase, and glutamate dehydrogenase 5, 10, and 15 days after treatment in the leaves of 3-week-old seedlings of pea (Pisum sativum L.) and sweet corn (Zea mays L.). The results indicate that sublethal concentrations of s-triazine compounds affect the physiological and biochemical events in plants which favor more utilization of carbohydrates for nitrate reduction and synthesis of amino acids and proteins. This content is only available as a PDF. © 1971 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)

Maretzki, A.; dela Cruz, A.; Nickell, L. G.

doi: 10.1104/pp.48.5.521pmid: 16657831

Abstract Evidence is presented for the increased excretion of amylolytic enzymes into a sugarcane cell culture medium when starch was substituted for sucrose as an energy source. The excretion was further enhanced by the inclusion of 1 μm gibberellic acid in the nutrient medium. The growth rate of the cells increased after they became adapted to starch relative to cells grown on sucrose, but the rate of amylolytic enzyme excretion remained unaltered. Amylolytic enzymes in the medium included α-amylase but the identity of one or more other enzymes related to starch hydrolysis remains in doubt. 1 This investigation was supported in part with funds provided by the United States Department of Agriculture Agreement No. 12-14-100-10430(34) to the Experiment Station of the Hawaiian Sugar Planters' Association. 2 Published with the approval of the Director as Paper No. 272 in the Journal Series of the Experiment Station, Hawaiian Sugar Planters' Association. This content is only available as a PDF. © 1971 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)

Kannangara, C. G.; Henningsen, Knud W.; Stumpf, P. K.; Appelqvist, Lars-Åke; von Wettstein, D.

doi: 10.1104/pp.48.5.526pmid: 16657832

Abstract The effect of seedling age and of the time of greening on the incorporation of 1-14C-acetate into lipids by isolated barley (Hordeum vulgare cultivar Svalöf's Bonus) plastids was examined. The fatty acid synthesizing capacity of plastids isolated from 5-day-old seedlings did not increase markedly from zero to 36 hours of greening nor was a light stimulation of fatty acid synthesis observed. However, an increasing capacity for fatty acid synthesis and an increasing light stimulation of this process with greening were attained by the plastids isolated from 7-, 9-, and 11-day-old seedlings. Plastids of 7-day-old dark-grown plants, which were illuminated at 2 foot-candles showed increasing capacity of 14C-acetate incorporation with significant flow into phospholipids and sulfolipid, low flow into digalactosyl diglyceride, and considerable flow into 6-methyl salicylic acid. Exposure of these plants to high light intensity for an hour resulted in chloroplasts that after isolation had a 10-fold increased capacity to incorporate 14C label into digalactosyl diglyceride, while the flow of 14C label into phospho- and sulfolipids was unaltered, and that into 6-methyl salicylic acid was drastically curtailed. With plastids from 7-day-old dark-grown plants in early stages of greening, essentially all the 14C label in the stroma fraction could be accounted for by 6-methyl salicylic acid, while the membrane lipids only contained small amounts of 14C label. As greening proceeded, the flow of 14C label into 6-methyl salicylic acid diminished sharply, and the lipids of the lamellar systems became increasingly labeled. Only palmitic and oleic acids were main sites of 14C label in the membrane lipids. The activity of acetyl CoA carboxylase present in plastids of 5- and 7-day-old dark-grown plants fell sharply as the etioplasts differentiated into chloroplasts. 2 Senior Postdoctoral Fellow of National Science Foundation, 1968. Permanent address: Department of Biochemistry and Biophysics, Davis, Calif. 95616. 3 Present address: Division of Physiological Chemistry, University of Lund, Sweden. 1 This investigation was supported by National Institutes of Health Grant GM 10819. This content is only available as a PDF. © 1971 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)

Boyer, J. S.

doi: 10.1104/pp.48.5.532pmid: 16657833

Abstract The inhibition of photosynthesis at low leaf water potentials was studied in soil-grown sunflower to determine the degree to which photosynthesis under high light was affected by stomatal and nonstomatal factors. Below leaf water potentials of −11 to −12 bars, rates of photosynthesis at high light intensities were insensitive to external concentrations of CO2 between 200 and 400 microliters per liter. Photosynthesis also was largely insensitive to leaf temperature between 10 and 30 C. Changes in CO2 concentration and temperature had negligible effect on leaf diffusive resistance. The lack of CO2 and temperature response for both photosynthesis and leaf diffuse resistance indicates that rates of photosynthesis were not limited by either CO2 diffusion or a photosynthetic enzyme. It was concluded that photosynthesis under high light was probably limited by reduced photochemical activity of the leaves at water potentials below −11 to −12 bars. 1 Supported by Grant B-036-I11 from the Office of Water Resources Research, Department of Interior. This content is only available as a PDF. © 1971 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)

Leopold, A. C.

doi: 10.1104/pp.48.5.537pmid: 16657834

Abstract From a comparison of the effects of seven growth retardants and abscisic acid (ABA) on various growth systems, it was found that the gibberellin-regulated growth of lettuce hypocotyls was uniquely inhibited by the growth retardant, α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine methanol (EL-531). Auxin-regulated growth of coleoptile sections was inhibited by Phosfon and only slightly by EL-531 and Alar. Cytokinin-regulated growth of Xanthium cotyledons showed little or no inhibition by any of the retardants. ABA was inhibitory in all three types of tests. The distinctive effects of EL-531 against gibberellin-stimulated growth and the general ability of gibberellic acid to relieve EL-531 inhibition suggest that this retardant acts in part against the gibberellin-stimulated growth system, but at a locus which discriminates between growth and nongrowth functions of gibberellic acid. It shows little or no antagonism of gibberellin actions which do not involve growth: the barley endosperm test and the Rumex leaf senescence test. 1 Journal Paper 4262, Purdue University Agricultural Experiment Station. This content is only available as a PDF. © 1971 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)

Wilson, A. M.

doi: 10.1104/pp.48.5.541pmid: 16657835

Abstract Drying of seeds of Agropyron desertorum (Fisch. ex Link) Schult. did not result in breakdown of α-amylase nor impair the ability of seeds to resume its synthesis when moistened again. β-Amylase activity did not change during 5 days of germination at a water potential of 0 atmosphere nor during 40 days of incubation at −40 atmospheres. Seeds synthesized α-amylase at 0, −20, and −40 atmospheres, but not at −60 atmospheres. At 0 and −20 atmospheres, the log of α-amylase activity was linearly related to hastening of germination. But at −40 atmospheres, seeds synthesized α-amylase during a time when there was little hastening of germination. Thus, it appears that other biochemical reactions are less drought-tolerant than synthesis of α-amylase. It is concluded that inhibition of α-amylase synthesis is not a controlling factor in the germination of these seeds at low water potentials. 1 Cooperative investigations of the Plant Science Research Division, Agricultural Research Service, United States Department of Agriculture, and the College of Agriculture, Washington State University, Pullman, Washington. College of Agriculture Scientific Paper 3593. This content is only available as a PDF. © 1971 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, C. Y.; Key, Joe L.

doi: 10.1104/pp.48.5.547pmid: 16657836

Abstract The dissociation of N2 gas-induced monomeric ribosomes from the pea root was studied by varying the concentration of KCl (or NH4Cl) and MgCl2 in the presence of dithiothreitol. These monoribosomes were shown to dissociate completely into subunits at 0.5m KCl or NH4Cl in the presence of 5 mm MgCl2. The 40S subunits were more susceptible to structural change in KCl than were the 60S subunits. On the other hand, the 60S subunits appeared to be more labile to NH4Cl. The activity of the subunits relative to aminoacyl-tRNA binding and peptide bond formation was investigated using subunits derived from 0.5 m KCl (or NH4Cl) in the absence and presence of 5 mm MgCl2. The 40S subunits were active in aminoacyl-tRNA binding only when dissociated in the presence of MgCl2. The 40S and 60S subunits combined in the presence of poly U were active in incorporation of 14C-phenylalanine from 14C-phenylalanyl-tRNA only when dissociation was achieved in the presence of 5 mm MgCl2. The KCl-dissociated subunits were much more active in protein synthesis than NH4Cl-dissociated subunits. 1 This research was supported by Atomic Energy Commission Contract AT(38-1)-643 to Joe L. Key. This content is only available as a PDF. © 1971 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)

Strichartz, Gary R.

doi: 10.1104/pp.48.5.553pmid: 16657837

Abstract The identity of the pigment responsible for the light-induced 518 nanometer absorbance change was investigated by extraction and reconstitution of spinach chloroplasts. Heptane extraction of carotene and quinones from lyophilized chloroplasts removes absorbance changes at 518 and 475 nanometers activated by both laser flash and continuous illumination. Some electron transport activity is always present, even in carotene- and quinone-depleted chloroplasts, but the light-induced pH increase disappears following the first extraction step. Readdition of pure β-carotene partially restores the 518 and 475 nanometer absorbance changes. 2 Present address: Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Wash. 98105. 1 This research was supported by United States Public Health Service Training Grant GM2G27709. Submitted in partial fulfillment of requirements for the degree of Doctor of Philosophy to the Graduate School of Arts and Sciences of the University of Pennsylvania. This content is only available as a PDF. © 1971 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)

Stowe, Bruce B.; Dotts, Mary Ann

doi: 10.1104/pp.48.5.559pmid: 16657838

Abstract Auxin-induced pea (Pisum sativum) stem section elongation is enhanced at levels of 3 to 40 micromolar by six new classes of alkane derivatives additional to those described earlier, providing that length of their molecules exceeds 20 A. Increasingly longer homologous series of alkyl chlorides, bromides and iodides, alkyl benzenes, dialkyl ethers, and sulfides show a logarithmically linear increase in specific activity above this length, reaching an optimum near 28 to 30 Å. Longer dialkyl ethers and sulfides are less effective, while steroids, or alkanes with substituents at both ends, are ineffective. Neither common metabolism nor common physical properties, other than over-all length of active molecules, seem to explain these results. However, the dimensions of the most abundant phospholipid of etiolated peas, 1-palmitoyl-2-linoleoyl-3-sn-phosphatidyl choline are such that a monolayer of this lecithin would contain cavities 20 Å long. It is postulated that lipids of this length or longer are active in the pea assay by forcing apart lecithin molecules, changing the charge distribution or chelating properties of a regulatory membrane. Steroid dimensions also match the cavity in lecithin monolayers and steroids would be maintained within such a cavity by hydrogen bonds. The name lipometrin for lipids whose physiological activity varies with length is proposed, among these, substances active in the pea bioassay could be termed oleanimins. 1 This work was supported in part by a grant from the National Institutes of Health (GM-06921) to B. B. Stowe. This content is only available as a PDF. © 1971 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)