Plant Physiology

Chimiklis, Phrosene E.; Heath, Robert L.

doi: 10.1104/pp.56.6.723pmid: 16659380

Abstract The unicellular algae Chlorella sorokiniana was used as a model system to investigate the interaction of ozone with plant cell membranes. Ozone induces K+ leakage from Chlorella sorokiniana similar to the electrolytic loss observed from many higher plants under stressful conditions. The kinetics of this leakage indicate that ozone initially interacts reversibly (within sec) with sites on membranes allowing a passive efflux of K+. This efflux ceases within minutes after the ozone stress is removed. This return to normal efflux is very temperature dependent. High intracellular osmolarity seems to be an important criterion of susceptibility to ozone injury in this model system, since rates of ozone-induced K+ leakage are less when the external osmotic potential is decreased by suspension of the cells in mannitol. Cell interaction with ozone is further complicated by a saturating-type dependence of the K+ efflux upon ozone concentration within the medium. 3 Present address: National Ecological Research Laboratory, United States Environmental Protection Agency, Corvallis, Ore. 1 This project has been financed in part with federal funds from the Environmental Protection Agency under Grant R-801311. 2 The contents of this paper do not necessarily reflect the views and policies of the Environmental Protection Agency. 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)

Tezuka, Takafumi; Yamamoto, Yukio

doi: 10.1104/pp.56.6.728pmid: 16659381

Abstract The specificities of phosphate donors and the effects of metal chelating agents and divalent metal ions on NAD kinase activation by phytochrome-far red-absorbing form (Pfr) were examined. ATP was the most efficient phosphorylating agent. Uridine 5′-triphosphate, cytidine 5′-triphosphate (CTP), inosine 5′-triphosphate, and guanosine 5′-triphosphate in this order caused significant phosphorylation in the dark. Under red light, striking photoactivation of NAD kinase was obtained with ATP and subsequently CTP. In the presence of exogenous Mg2+, which is required for NAD kinase activity, α-nitroso-β-naphthol, cyanide, and dimethylglyoxime, strongly inhibited the activation by red light without affecting the level of NAD kinase in the dark. Of the divalent cations tested with the KCN-treated phytochrome preparation, only Co2+ was effective for photoactivation of NAD kinase. Even when Mg2+, an essential component of NAD kinase, was added to the assay system, the further addition of Co2+ was required for the activation of NAD kinase by Pfr. 1 To whom requests for reprints should be sent. 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)

Braun, Joseph W.; Khan, Anwar A.

doi: 10.1104/pp.56.6.731pmid: 16659382

Abstract The concentrations of abscisic acid in Grand Rapids lettuce (Lactuca sativa L.) seeds imbibed under conditions which promote or inhibit germination were determined by electron capture-gas chromatography. The concentration of abscisic acid in dry seeds was 12 to 14 nanograms per 100 milligrams. During 24-hour imbibition, the abscisic acid content diminished more rapidly during conditions which allow germination (25 C in light) than in conditions which inhibited germination (35 C in light or darkness at 25 C). A decrease in endogenous levels of abscisic acid was not always correlated with germination. 1 This investigation was supported in part by grants from the Herman Frasch Foundation and the American Seed Research Foundation to A. A. K. 2 This work was approved by the Director of the New York State Agricultural Experiment Station as Journal Series Paper No. 2208. 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)

Yamamoto, Naoki; Hasegawa, Masao; Sasaki, Satohiko; Asakawa, Sumihiko

doi: 10.1104/pp.56.6.734pmid: 16659383

Abstract Polysome formation in the embryos of Pinus thunbergii seeds was studied. Free ribosomes were dissociated to smaller subunits in a high salt buffer, but the complex ribosomes were not. The free ribosomes could be distinguished from monomer ribosomes derived from polysomes after RNase treatment. The monomer ribosomes present in the embryos of the dark-imbibed seeds were predominantly free ribosomes; very small quantities of polysomes could be detected in the embryos from dark-imbibed seeds. Such polysomes remained at a very low level during dark imbibition at least for a month. The level of polysomes increased 4 hours after a brief exposure to red light. The effect of red light on polysome formation was partially reversed when followed by far red light irradiation. 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)

Williamson, Francis A.; Morré, D. James; Jaffe, Mark J.

doi: 10.1104/pp.56.6.738pmid: 16659384

Abstract Distribution of phytochrome (as Pfr) among membranes from soybean hypocotyls (Glycine max L. cv. Wayne) was determined by the combined techniques of cell fractionation, difference spectrometry, and electron microscopic morphometry. More than 90% of the phytochrome was found in the soluble fraction. With homogenates prepared in the presence or absence of Mg2+, the portion associated with membrane was only 6.5% and 1%, respectively. In the presence of Mg2+, the content of particulate phytochrome correlated with the amount of endoplasmic reticulum with attached ribosomes in the fractions but not with mitochondria or other membranes (including endoplasmic reticulum membranes from which the ribosomes may have been lost during cell fractionation). In the absence of Mg2+, phytochrome was associated with a “heavy” plasma membrane fraction. The phytochrome content was sufficiently low to be accounted for by a contamination of less than 10% by rough-surfaced fragments of endoplasmic reticulum. The findings show association of phytochrome with a particulate fraction enriched in rough-surfaced fragments of endoplasmic reticulum but do not rule out cosedimentation of some unknown or unspecific phytochrome aggregate with this fraction. 1 Work was supported in part by the Joint Highway Research Project, Purdue University (D.J.M.), the Office of Water Resources, Purdue University (D.J.M.), and Grant GB-3325 from the National Science Foundation (M.J.J.). Purdue University AES Journal Paper No. 5817. 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)

Ames, Ira H.; Mistretta, Patricia W.

doi: 10.1104/pp.56.6.744pmid: 16659385

Abstract Seedlings of the tumor-prone amphiploid Nicotiana suaveolens X N. langsdorffii were grown on nutrient medium supplemented with indoleacetic acid (IAA) and scored at regular intervals for the incidence of tumor formation. IAA at 2 × 10−5m caused a significant reduction in the rate of tumor formation. Plants were also grown on nutrient medium under two different intensities of illumination, and the endogenous level of IAA was determined in 23-day-old seedlings. Those grown under 2000 ft-c of illumination had a higher incidence of tumors and a significantly lower level of endogenous IAA than those grown under 500 ft-c of illumination. A correlation in time between decline in the endogenous level of IAA and onset of tumor formation was demonstrated in greenhouse-grown plants. 1 This work was supported by Grant BO-32864 from the National Science Foundation. 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)

Nadar, Hassan M.; Clegg, Max D.; Maranville, Jerry W.

doi: 10.1104/pp.56.6.747pmid: 16659386

Abstract Growth-promoting action of simazine and other s-triazine herbicides was detected by the use of sorghum (Sorghum bicolor [L]. Moench) callus tissue and the chlorophyll retention test. Soil application of simazine [2-chloro-4, 6-bis(ethylamino)-s-triazine] at sublethal levels nearly doubled the growth-promoting action of sorghum root exudates. Treated plants yielded up to 26% more total protein than untreated plants. This indicated that the level of callus growth-promoting action in the root exudate of the plant has a positive effect on its final total protein yield and confirms a positive effect of simazine on total protein content in certain instances. The results may provide a new understanding of the mode of action of s-triazines applied at sublethal levels in increasing protein content and certain enzymic activities of treated plants. It is speculated that the growth-promoting action of these herbicides is hormonal in nature and most likely kinetin-like. 1 Published as Paper No. 3939, Journal Series, Nebraska Agricultural Experiment Station. Research reported was conducted under Project No. 12-69, and was partially supported by grants from the Rockefeller Foundation and United States Agency for International Development. 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)

Berlyn, Mary B.; Zelitch, Israel

doi: 10.1104/pp.56.6.752pmid: 16659387

Abstract Haploid tobacco (Nicotiana tabacum L.) cell cultures derived from quite different cultivars have been grown photoautotrophically in medium lacking sucrose and with 1.6 μm naphthaleneacetic acid and 1.5 μm isopentenylaminopurine. Cells were grown for 5 months on agar medium in Petri plates in air with dry weight increases of 1.5- to 3-fold per month. Callus cells were also grown photoautotrophically for at least three consecutive transfers 3 weeks apart in shallow liquid medium in horizontally placed gas-washing bottles where they were gassed continuously with air or air enriched with CO2. Raising the CO2 level in the air surrounding the cells increased the growth rate, and after about 3 weeks in 1% CO2 the dry weight was approximately 3-fold greater than the inoculum. Growth rates remained about the same after each consecutive transfer. Autotrophic growth with this regime is not restricted to specific clones or cultivars. Photosynthetic measurements in an atmosphere containing 14CO2 established that rates of CO2 assimilation in the callus cells at high CO2 levels were similar to those of leaves on a chlorophyll basis, but were much slower on a fresh weight basis. Photosynthetic light saturation was achieved at an irradiation of about 125 μeinsteins m−2 sec−1 (400-700nm). The availability of photosynthetically dependent haploid cells provides an opportunity to select photosynthetic mutations which can be expressed in plants regenerated from these cells. 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, Paul A.; Montague, Michael J.; Tepfer, Mark; Rayle, David L.; Ikuma, Hiroshi; Kaufman, Peter B.

doi: 10.1104/pp.56.6.757pmid: 16659388

Abstract Extensibility characteristics of Avena stem segments treated with gibberellic acid (GA) were investigated in living internodes using a microgrowth method and in partially extracted cell walls subjected to Instron extensometer analysis. Both techniques showed that treatment with GA greatly increases internodal plasticity, but has virtually no effect on internodal elasticity. The increase in plasticity occurred 1 to 2 hours after the initiation of hormone treatment, which is similar to the time of onset of GA-enhanced growth and cell wall synthesis. Cycloheximide was shown to inhibit the effect of GA on plasticity. 2 Department of Biology, University of Michigan-Flint, Flint, Mich. 48503. 3 Present address: Monsanto Chemical Company, St. Louis, Mo. 4 Present address: Department of Botany, University of Washington, Seattle, Wash. 98195. 5 Department of Botany, San Diego State University, San Diego, Calif. 92115. 6 To whom requests for reprints should be addressed. 1 This research was supported in part by National Science Foundation Grant GB 39585 to D.L.R., grants from the American Cancer Society and the National Science Foundation to P.B.K., and the Atomic Energy Commission to Peter Albersheim. 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)

Quebedeaux, Bruno; Havelka, Ulysses D.; Livak, Kenneth L.; Hardy, Ralph W. F.

doi: 10.1104/pp.56.6.761pmid: 16659389

Abstract Dry matter accumulation, nitrogen content and N2 fixation rates of soybean (Glycine max [L.] Merr. cv. Wye) plants grown in chambers in which the aerial portion was exposed to a pO2 of 5, 10, 21, or 30% and a pCO2 of 300 μl CO2/l or a pO2 of 21% and a pCO2 of 1200 μl CO2/l during the complete growth cycle were measured. Total N2[C2H2] fixed was increased by CO2/O2 ratios greater than those in air and was decreased by ratios smaller than those in air; the effects on N2 fixation of decreased pO2 or elevated pCO2 were quantitatively similar during the period of vegetative growth. Decreased pO2 produced a smaller increase then elevated pCO2 during the reproductive period, presumably because of the decreased sink activity of the arrested reproductive growth under subambient pO2. At a pO2 of 5% and a pCO2 of 300 μl CO2/l total N2 fixed was increased 125% and per cent nitrogen content in the vegetative parts was increased relative to air while that in the seed was decreased. Dry matter production was increased and reproductive growth was arrested as previously reported for plants receiving only fertilizer nitrogen. At a pO2 of 30% and a pCO2 of 300 μl CO2/l total N2 fixed was decreased 50% and per cent nitrogen content in the vegetative part was increased relative to air while that in the reproductive structures was unaffected. Dry matter production was similarly decreased in both vegetative and reproductive structures. These effects of altered pO2 in the aerial part on N2 fixation are consistent with the hypothesis that the amount of photosynthate available to the nodule may be the most significant primary factor limiting N2 fixation while sink activity of the reproductive structures may be a secondary factor. 1 Contribution No. 2279, Central Research and Development Department, Experimental Station, E. I. du Pont de Nemours and Company, Wilmington, Del. 19898. 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)