Plant Physiology

Dumbroff, E. B.; Michel, B. E.

doi: 10.1104/pp.42.11.1465pmid: 16656680

Abstract The effects of factorial combinations of N, P and Mg on some of the interrelationships among nutrient ions as they occurred in seedlings of slash pine were investigated. In similar studies, true interactions have not always been differentiated from apparent interactions, the result of comparing foliage concentrations in plants with widely divergent growth rates. To prevent this, nutrient solutions were formulated to produce conditions ranging only from slight deficiency through luxury consumption. This relatively narrow range of nutrition allowed actual interactions to be separated from those changes in foliage concentration that are primarily a result of large differences in growth. The needles were analyzed for total and soluble N and total P, K, Ca, Mg and Na. Each level of each nutrient variable had a significant effect on the concentration of 1 or more dissimilar elements. The familiar depressive effect of N on foliar P was observed; however this relationship was shown to be primarily the result of growth dilution rather than anion antagonism. Increased Mg did antagonistically reduce the uptake of Ca and, generally, K. Increments of P not required for growth stimulated uptake of N, Ca, Mg and K. No relationship was found between Mg supply and P accumulation. 2 Present address: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada. 1 Supported in part by the Southern Forest Experiment Station of the United States Forest Service. This content is only available as a PDF. © 1967 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)

Throneberry, G. O.

doi: 10.1104/pp.42.11.1472pmid: 16656681

Abstract Conidia of Verticillium albo-atrum Reinke and Berthold, collected from shake cultures grown in Czapek broth, were sonified for 4 or 8 minutes or ground frozen in a mortar to obtain cell-free homogenates. These were assayed for certain enzymes associated with respiratory pathways. Malic dehydrogenase was the most active, glucose-6-P and NADH dehydrogenase were less active, NADH-cytochrome c reductase, NADPH dehydrogenase, and cytochrome oxidase were low in activity, and succinic dehydrogenase and succinic cytochrome c reductase were very low to negligible in activity. No NADH oxidase activity was detected. With the exception of NADH-cytochrome c reductase and possibly succinic dehydrogenase and cytochrome c reductase, there was no evident increase in specific activity of the enzymes during germination. Some NADH-cytochrome c reductase and a small amount of succinic-dehydrogenase and cytochrome c reductase were associated with the particulate fraction from 105,000 × g centrifugation. The other enzymes, including cytochrome oxidase, almost completely remained in the supernatant fraction. Menadione and vitamin K-S(II) markedly stimulated NADH-cytochrome c reductase activity in the supernatant fraction but had much less effect on NADPH-cytochrome c reductase in this fraction or on either of these enzyme systems in the particulate fraction. Electron transport inhibitors affected particulate NADH- and NADPH-cytochrome c reductase activity but had no effect on these in the supernatant fraction. This content is only available as a PDF. © 1967 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)

Yaniv, Zohara; Mancinelli, Alberto L.; Smith, Phyllis

doi: 10.1104/pp.42.11.1479pmid: 16656682

Abstract Prolonged irradiation with continuous or intermittent far red prevents the germination of tomato and cucumber seeds. The inhibitory efficiency of intermittent far red decreases with the lengthening of the interval between successive irradiations, and with the increase of temperature. If each far red irradiation is followed by red, germination is restored. Intermittent far red is less inhibitory than intermittent red-far red when red is given immediately before each far red. This effect is more evident when the interval between successive irradiation becomes longer. 1 Research supported in part by a National Science Foundation grant, NSF-GB-3299, to A. L. Mancinelli. This content is only available as a PDF. © 1967 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)

Elzam, O. E.; Hodges, T. K.

doi: 10.1104/pp.42.11.1483pmid: 16656683

Abstract Calcium (or magnesium) sulfate or chloride was found to inhibit energy dependent potassium transport in excised corn roots. This Ca2+ inhibition of K+ transport was most pronounced during the initial phases of transport. As the absorption periods were lengthened the effect of Ca2+ gradually changed from an inhibition to a typical promotion (after about 30-45 mins) of K+ transport. Kinetic analysis indicated the inhibition to be of a non-competitive nature. Identical experiments with excised barley roots showed that CaSO4 had no effect on K+ absorption whereas CaCl2 had a typical stimulatory effect on K+ absorption. Kinetic analysis indicated that both corn and barley have efficient K+ transporting systems but barley roots are approximately 5 times more active (on a fr wt basis) than corn roots. These results illustrate the hazards involved in applying results obtained with 1 (or even several) plant species to all species. 2 Present address: Biology Department, Case-Western Reserve University, Cleveland, Ohio. 1 Supported by the University of Illinois Research Board and National Science Foundation Grants GB-2281 and GB-5549. This content is only available as a PDF. © 1967 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)

Siegel, S. M.; Lederman, Muriel; Daly, Olive; Roberts, Karen

doi: 10.1104/pp.42.11.1489pmid: 16656684

Abstract Rice germinates equally well when incubated in air and in nitrogen. It was therefore chosen for a comparative study of the effect of oxygen status in a single organism upon the activity of conventional metabolic poisons. Inhibitor activity was based upon the concentration required for 50% inhibition of germination. The inhibitors were: AgNO3, HgCl2, phenylmercuric acetate, iodoacetamide, KCN, NaN3, NaF, fluoroacetate, 2,4-dinitrophenol, Na2HAsO4 and CO. Only 5 inhibitors out of 11 differed significantly in their effects on aerobic and anaerobic germination. These included phenylmercuric acetate (N2), sodium fluoroacetate (air), NaN3 (air), and 2,4-dinitrophenol (N2). CO activity was manifest only in air and it was photo-reversible. The effects of CO, NaN3, and fluoroacetate were consistent with their conventional role in aerobic metabolism. The failure of KCN to discriminate was attributed to its relative non-specificity. 2,4-Dinitrophenol behaved anomalously, requiring a 20-fold lower concentration for inhibition under nitrogen than under air. Among sulfhydryl poisons, only phenylmercuric acetate differentiated between germination in air and nitrogen and was nearly 8 times more active under nitrogen. Uptake measurements using phenylmercuric acetate and arsenate showed both compounds to be in greater concentration under aerobic conditions, thereby rendering unlikely any explanation based upon greater permeability under nitrogen. In addition to other anomalies, the fact that NaN3, fluoroacetate and CO inhibited anaerobic germination at any concentration requires explanation. It was concluded that the general significance and utility of metabolic inhibitor studies in vivo required further evaluation. 1 This work was carried out under National Aeronautics and Space Administration contract NASw-767. Present address of senior author is Department of Botany, University of Hawaii, Honolulu, Hawaii. This content is only available as a PDF. © 1967 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)

Tepper, Herbert B.; Hollis, Charles A.; Galson, Eva. C.; Sondheimer, Ernest

doi: 10.1104/pp.42.11.1493pmid: 16656685

Abstract In excised embryos of Fraxinus ornus, the first macroscopic sign of germination is a curvature near the root apex. Histological studies show that this curvature is due to cell elongation on the convex side and is accompanied by cell division. Metabolic changes, manifested by the disintegration of protein bodies and tissue differentiation, also occur during this time. In embryos treated with phleomycin cell division is completely inhibited but elongation, root hair formation, disintegration of protein bodies, and differentiation are still detectable. Phleomycin also drastically inhibits the formation of chlorophylls and the fresh weight increase of embryos. 1 Supported by NSF Grant 4262 and the McIntire-Stennis Cooperative Forestry Research Program of the U.S.D.A. This content is only available as a PDF. © 1967 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)

Srivastava, B. I. Sahai; Arglebe, C.

doi: 10.1104/pp.42.11.1497pmid: 16656686

Abstract The effect of sucrose, Mg2+ and deoxycholate on the yield of ribosomes from barley leaves was determined and the changes in the amount and the composition of ribosomes during senescence of intact and excised first seedling leaves were examined. The extraction medium containing 20 mm tris-HCl, 0.25 m sucrose, 1 mm MgCl2 and 0.5% deoxycholate (pH 7.8) gave the maximum yield of polyribosomes and ribosomes. That polyribosomes were not non-specific aggregates was suggested by their capacity to synthesize nascent protein. During senescence of both intact and excised leaves polyribosomes and ribosomes were lost and the ribosomes-polyribosomes which originally contained 48% protein and 52% RNA showed substantial decline in the protein content during senescence indicating the degradation of ribosomes and the loss of their function. 1 Supported by National Science Foundation Grant GB-4720X. This content is only available as a PDF. © 1967 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)

Sargent, Malcolm L.; Briggs, Winslow R.

doi: 10.1104/pp.42.11.1504pmid: 16656687

Abstract The expression of a circadian rhythm of conidiation by timex, a strain of Neurospora crassa, is inhibited by growth in continuous white light. The action spectrum for this effect has a strong peak (with minor subpeaks) in the blue region of the visible spectrum, and a broad shoulder in the near ultraviolet. This action spectrum suggests that a carotenoid or flavin compound may be the photoreceptor, but does not allow one to determine conclusively whether the receptor is indeed a carotenoid, flavin, or some other unrelated pigment. Two lines of evidence suggest that a carotenoid is not the photoreceptor. First, the in vivo absorption spectrum of timex (representing the sum of the spectra of the individual pigments present, predominantly carotenoids) has peaks at wavelengths 10 to 20 mμ longer than those of the action spectrum peaks. Second, an albino-timex has normal photosensitivity, a situation requiring that the photoreceptor, if carotenoid, be a quantitatively minor constituent of the total carotenoid complement. The magnitude and direction of phase-shift resulting from a standard dose of white light given at different times in the daily cycle of timex varies in the manner reported for other organisms. Additional phase-shift experiments have shown that there are no major transients in the attainment of a new equilibrium after a phase-shifting perturbation, and that 2 light reactions (rapidly and slowly saturating) may be involved in the phase-shift response. 2 Present address: Department of Botany, University of Michigan, Ann Arbor, Michigan 48104. 3 Present address: Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138. 1 Supported by grants GB-2846 and GB-2751 to W. R. Briggs, from the National Science Foundation, a grant from Research Corporation to W. R. B., and by a National Science Foundation predoctoral fellowship to M. L. Sargent. Taken in part from a thesis submitted to Stanford University by M. L. S. in partial fulfillment of the requirements for the Ph.D. degree. This content is only available as a PDF. © 1967 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)

Shumate, W. H.; Reid, H. B.; Hamner, K. C.

doi: 10.1104/pp.42.11.1511pmid: 16656688

Abstract The inhibitory effect of light interruptions given during the photophobe phases of a 72-hour cycle was studied with Biloxi soybean [Glycine max (L.) Merr.]. The basic 72-hour cycle consisted of 8 hours of light followed by 64 hours of darkness and was repeated 7 times. Supplementary white light treatments given at the twenty-fourth and/or forty-eighth hour of the cycle (photophil phases) promoted the flowering levels of the controls and kept light treatments given at the most inhibitory points from inhibiting flowering completely. Such supplementary light treatments did not affect the time of maximum sensitivity to light interruptions. When 30-minute light breaks were used, maximum inhibition occurred at the 16-, 43-, and 63-hour points. The duration of the light breaks affected the time of maximum inhibition when given during the second photophobe phase. The time of maximum inhibition occurred earlier with 4-hour light breaks than with either 3-minute or 2-hour light interruptions. Three-minute red light interruptions produced essentially the same effect as 3-minute white light interruptions. Such treatments inhibited flowering completely in the first photophobe phase, inhibited flowering to only a small degree in the second photophobe phase, and inhibited flowering to an intermediate degree in the third photophobe phase. Far-red light interruptions strongly inhibited flowering in the first photophobe phase, especially when given early in the dark period. Three minutes of supplementary white light given at the twenty-fourth or forty-eighth hour of the cycle partially overcame the inhibitory effect of far-red light. Four hours of supplementary white light at these times completely overcame the far-red inhibition. 1 This work was supported in part by National Science Foundation Grant No. GB-3895 and by National Institutes of Health, Grant No. GM-12061. This content is only available as a PDF. © 1967 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)

Muir, Robert M.; Fujita, Toshio; Hansch, Corwin

doi: 10.1104/pp.42.11.1519pmid: 6080870

Abstract The analysis of substituent constants for the lipophilic and electronic factors in the auxin activity of substituted phenylacetic acids in elongation of coleoptile segments shows that these factors parallel those for the phenoxyacetic acids but assign reactivity in growth promotion to the meta position of phenylacetic acid. The inhibitory effects with supra-optimal concentrations are highly dependent on the lipophilic character of the molecules. 2 Permanent address: Department of Agricultural Chemistry, Kyoto University, Kyoto, Japan. 1 Supported in part by Research Grant GM 07492 from the National Institutes of Health. This content is only available as a PDF. © 1967 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)