Plant Physiology

Schneider, Michael J.; Lin, Julia C. J.; Skoog, Folke

doi: 10.1104/pp.44.9.1207pmid: 5379105

Abstract Edstrom's microphoresis technique has been employed to determine the quantitative alterations in nucleic acid content and base composition of individual cells associated with the initiation of bud primordia in Funaria hygrometrica. The filamentous protonema of this moss initiates bud cells which through repeated divisions form the leafy gametophores. The cytokinin, 6-furfurylaminopurine (kinetin), was used to induce the differentiation of bud cells from protonematal cells. The total RNA content of kinetin-induced bud cells (22.0 μμg/cell) was nearly 15 times that of protonematal cells (1.6 μμg/cell). The same dramatic increase in total RNA was apparent in bud cells which developed spontaneously in older cultures. As would be predicted, the adenine (A) to guanine (G) ratio for DNA from bud and protonematal cells was identical (0.7). The A:G ratio for RNA from bud cells (1.0) was much lower than that from protonematal cells (1.7). Thus, kinetin-induced differentiation in this system involves a dramatic increase in total RNA, the base composition of which approaches that of DNA. The base composition (A:G ratio) of DNA remains constant. 2 Present address: Department of Biological Sciences, Columbia University, New York, New York 10027. 1 Supported in part by a Public Health Service Fellowship (1-F3-CA-29, 934-01) from the National Cancer Institute to M. J. Schneider and by N.S.F. grant No. GB-6994X to F. Skoog. This content is only available as a PDF. © 1969 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)

Russell, D. W.; Galston, A. W.

doi: 10.1104/pp.44.9.1211pmid: 16657193

Abstract Red light inhibits the growth of etiolated pea internodes, causes a shift toward higher indoleacetic acid (IAA) concentrations in the IAA dose-response curve of excised sections, and promotes the synthesis in intact internodes of kaempferol-3-triglucoside. Gibberellic acid (GA3) prevents all 3 effects, the first effect substantially and the last 2 completely. This suggests GA3 blockage of an early or basic event initiated by the active form of phytochrome. The red light-induced shift in the IAA dose-response curve of excised sections is consistent with a light-induced increase in the activity of an IAA destruction system, since the magnitude of the red light inhibition varied with IAA concentration. The red light and GA3 effects on growth and on flavonoid synthesis are consistent with the view that phytochrome may control growth by regulating the synthesis of phenolic compounds which act as cofactors in an IAA-oxidase system. GA3 reversal of the red light-induced shift in the IAA dose-response curve involves both growth promotion and inhibition by GA3 at different IAA concentrations and this, together with the GA3 reversal of light-induced flavonoid synthesis, supports the suggested regulatory role of phenolic compounds in growth. 2 Present address: Department of Physiological Chemistry, University of Wisconsin, Madison, Wisconsin 53706. 1 Part of this work formed portion of a dissertation by Dr. D. W. Russell, presented to the Graduate School of Yale University in partial fulfillment of the requirements for the Ph.D. degree. This content is only available as a PDF. © 1969 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)

Stinson, Robert A.; Spencer, Mary

doi: 10.1104/pp.44.9.1217pmid: 16657194

Abstract A method is described for the preparation, from a subcellular particulate fraction of wax bean cotyledons, of a soluble enzyme system that is capable of converting β-alanine to ethylene. In the presence of ATP, CoA, thiamine pyrophosphate, MgSO4, and pyridoxal phosphate, ethylene production is maximum at a 0.5 mm concentration of β-alanine. The system exhibits a pH optimum at 7.0 but when the pH is raised above 8, evolution of the volatile again increases and continues to do so up to pH 12. The enzyme system is stimulated by either NADPH or NADH; the concentration of NADPH necessary to obtain maximum activity is twice that of NADH. The requirement for a reducing agent is in agreement with the proposal that malonate semialdehyde, formed by an aminotransferase reaction from β-alanine, is reduced to β-hydroxypropionate. Both malonate semialdehyde and β-hydroxypropionate are better stimulators of production of the volatile in the soluble system than is β-alanine, and β-hydroxypropionate is a better stimulator than malonate semialdehyde. This system is also able to incorporate tritium from tritiated water into ethylene; this supports the proposal that ethylene is formed by the decarboxylation of acrylate, the latter being formed from β-hydroxypropionate. Experiments with both cold and labeled malonate suggest that this compound stimulates ethylene production by acting as an end product inhibitor that prevents the loss of malonate semialdehyde from the pathway. Malonate does not appear to serve as a precursor. Addition of cytoplasmic enzymes to the `soluble system' (prepared from particulate enzymes) results in a considerable boost in ethylene production, but the specific activity (mμ1 / mg protein) is lowered from that of the particulate enzymes alone. 2 Present address: Department of Biochemistry, University of Bristol, Bristol, Bristol, England. 1 The authors are grateful to the National Research Council of Canada for a grant-in-aid (A-1451) of this research and for a studentship to R.A.S. This content is only available as a PDF. © 1969 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)

Pollard, Clifford J.

doi: 10.1104/pp.44.9.1227pmid: 16657195

Abstract The sequence in which a variety of enzymes and metabolites are affected by gibberellic acid after application of the hormone to aleurone layers of half seeds of barley (Hordeum vulgare var. Betzes) and half seeds of wheat (Triticum aestivum var. Gensee) was investigated. With barley aleurone layers the first hormonal effect observed was the increased secretion of soluble carbohydrate, some of which appears to be a glucan containing some β-1,3 linkages. This was followed by increased oxygen consumption and increased secretion of ATPase, GTPase, phytase, phosphomonoesterase, phosphodiesterase, inorganic phosphate, carbohydrates other than amylase, peroxidase and amylase. Similar sequential effects were seen in wheat half seeds. Increased activity of alcohol dehydrogenase in barley seeds was elicited by the hormone but there was no effect on glucose-6-phosphate isomerase. This content is only available as a PDF. © 1969 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)

Pitman, M. G.

doi: 10.1104/pp.44.9.1233pmid: 16657196

Abstract The uptake of Na+ and K+ by barley seedlings grown on aerated or non-aerated solutions was studied. Plants growing in culture solution took up K+ with high selectivity whether the solution was aerated or not. Roots of plants grown on aerated CaSO4 and transferred to a solution of KCl and NaCl had a lower preference for K+ than roots of plants grown on non-aerated CaSO4. Both kinds of low-salt roots were much less able to discriminate between K+ and Na+ than high-salt roots grown on a culture solution. The different levels of K+ selectivity are suggested to be related to H+ release from the tissue. 1 On leave from School of Biology, University of Sydney, Sydney, Australia. This content is only available as a PDF. © 1969 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, C. A.; Rinne, R. W.

doi: 10.1104/pp.44.9.1241pmid: 16657197

Abstract ATP sulfurylase activity varied greatly among different leaves on the soybean plant [Glycine max (L.) Meer.], and high levels of activity did not appear in the leaves until the seedlings were about 3 weeks old. In general, leaves from the top of the plant had a higher activity than leaves from the bottom of the plant. A much greater activity was found in soybean leaves than in soybean roots. The absence of sulfate in the nutrient solution resulted in higher enzyme activity in leaves from young plants and in lower activity in leaves from older plants. Over the growing season, however, ATP sulfurylase activity appeared to be related to sulfur content of the leaf. Several other plant species also had measurable levels of ATP sulfurylase. 1 Cooperative investigations of Crops Research Division, Agricultural Research Service, United States Department of Agriculture, and Illinois Agricultural Experiment Station, Urbana, Illinois. Publication No. 566 of the United States Regional Soybean Laboratory, Urbana, Illinois. This content is only available as a PDF. © 1969 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)

Quinlan, J. D.; Weaver, R. J.

doi: 10.1104/pp.44.9.1247pmid: 16657198

Abstract Leaves of Vitis vinifera L., nearly fully expanded, imported only trace amounts of 14C following assimilation of 14CO2 by a lower leaf on the same shoot, but benzyladenine (BA) application at 4.4 × 10−3m caused a marked increase in the movement of 14C into these leaves. Older leaves near the shoot base were less responsive; BA treatment alone had little effect on import of labeled assimilates from adjacent leaves but when the BA-treated leaves were darkened there was an increased import of labeled materials. When these 2 treatments were combined and applied to leaves on shoots with ringed bases, relatively high levels of radioactivity were detected in the BA-treated leaves but under these conditions darkening, without the application of BA, also resulted in an increased import of 14C. Accumulation of imported 14C was found to be restricted to the area of the leaf blade treated with BA. Separation of labeled compounds in ethanol extracts of treated leaves showed a lower percentage of radioactivity present in the sugar fraction from BA-treated leaves and an increased percentage present in the amino acid fraction. This content is only available as a PDF. © 1969 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)

Hart, James W.; Filner, Philip

doi: 10.1104/pp.44.9.1253pmid: 16657199

Abstract The sulfur requirements of tobacco (Nicotiana tabacum L. var. Xanthi) XD cells grown in chemically defined liquid media can be satisfied by sulfate, thiosulfate, l-cyst(e)ine, l-methionine or glutathione, and somewhat less effectively by d-cyst (e) ine, d-methionine or dl-homocyst (e)ine. Sulfate uptake is inhibited after a 2 hr lag by l-cyst (e)ine, l-methionine, l-homocyst(e)ine or l-isoleucine, but not by any of the other protein amino acids, nor by d-cyst(e)ine. l-cyst(e)ine is neither a competitive nor a non-competitive inhibitor of sulfate uptake. Its action most closely resembles apparent uncompetitive inhibition. Inhibition of sulfate uptake by l-cyst(e)ine can be partially prevented by equimolar l-arginine, l-lysine, l-leucine, l-phenylalanine, l-tyrosine or l-tryptophan, but is little affected by any of the other protein amino acids. The effective amino acids are apparent competitive inhibitors of l-cyst(e)ine uptake after a 2 hr lag. Inhibition of sulfate uptake by l-methionine cannot be prevented, nor can uptake of l-methionine be inhibited by any single protein amino acid. The results suggest the occurrence of negative feedback control of sulfate assimilation by the end products, the sulfur amino acids, in cultured tobacco cells. 1 Present address: Department of Botany, University of Aberdeen, Aberdeen, Scotland. This content is only available as a PDF. © 1969 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)

Nitsos, Ronald E.; Evans, Harold J.

doi: 10.1104/pp.44.9.1260pmid: 16657200

Abstract An investigation was made to determine the univalent cation requirements of starch synthetase from a variety of plant species of economic importance. The particulate enzyme from sweet corn was shown to have an absolute requirement for potassium, with the optimum activation occurring at 0.05 M KCl. Rubidium, cesium, and ammonium were 80% as effective as potassium while sodium and lithium were respectively 21% and 8% as effective as potassium. The KA for potassium was determined to be 6 mM. In the case of the particulate starch synthetase from wheat, bush beans, field corn, soybeans, peas, or potatoes, considerable stimulation of enzyme activity was obtained by the addition of potassium to the reaction mixture. In these studies, low enzyme activity was observed in the absence of added potassium, but the content of endogenous univalent cations in the reactions may be sufficient to account for the activities observed. Anions of various types had no effect on starch synthetase activity. Divalent cations produced slight activation in the presence or absence of potassium. All efforts to show a potassium requirement for glycogen synthetase from rat liver have been negative. 2 Present address: Department of Biology. Southern Oregon College, Ashland. Oregon 97520. 1 Technical paper 2683 of the Oregon Agricultural Experiment Station. This research was supported in part by a research grant (AM-08123) from the United States Public Health Service. This research will be included in a thesis to be submitted as partial fulfillment of the requirements for a Ph.D. degree at Oregon State University. This content is only available as a PDF. © 1969 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)

Hancock, Joseph G.

doi: 10.1104/pp.44.9.1267pmid: 16657201

Abstract Rates of uptake of 3-o-methylglucose (MeG) by squash (Cucurbita maxima) hypocotyl sections from above lesions caused by Hypomyces solani f. sp. cucurbitae, race 1, are 2-fold greater than uptake by comparable tissues from healthy plants. Kinetic analyses indicate (i) that a single (constitutive) carrier system, with a Michaelis constant (Km) of 25 to 30 mm, mediates the transport of MeG into healthy hypocotyl cells and (ii) that an additional (inducible) system with a much lower Km (ca. 2 mm) is present in diseased hypocotyls. In both systems MeG uptake is inhibited competitively by glucose. The inducible transport system (s) in diseased tissues has a higher temperature coefficient, greater sensitivity to metabolic inhibitors and larger accumulation capacity than the one in healthy plants. While the nature of the constitutive system is ambiguous, the inducible carrier mechanism is a typical active transport system. These results indicate that increased rates of uptake and accumulation of metabolites by diseased tissues can be caused by new transport systems. This content is only available as a PDF. © 1969 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)