PLANT PHYSIOLOGY

Homann, Peter H.

doi: 10.1104/pp.88.1.1pmid: 16666246

Abstract This article summarizes the present state of knowledge about the organization of the water oxidizing polypeptide complex of photosynthesis and the mechanism of its operation. Spectacular advances have been made in recent years, but many questions remain to be answered. Among them are those concerned with the organization and binding of the functional Mn, its specific role in the oxidant storage that precedes the formation of one oxygen from two water molecules, and its cooperation with other redox-active constituents. Much is still to be learned also about the function of the individual polypeptides and about the role of the cofactors Ca2+ and Cl−. Differences between the organization of the water oxidizing complexes in green plants and cyanobacteria suggest, furthermore, that in vivo their water oxidizing mechanisms must operate under different, still unrecognized constraints. This content is only available as a PDF. © 1988 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, Anthony G.; Espie, George S.; Canvin, David T.

doi: 10.1104/pp.88.1.6pmid: 16666280

Abstract Chlorophyll a fluorescence of Synechococcus UTEX 625 was quenched during the transport of inorganic carbon, even when CO2 fixation was inhibited by iodoacetamide. Measurements with a pulse modulation fluorometer showed that at least 75% of the quenching was due to oxidation of Qa, the primary acceptor of photosystem II. Mass spectrometry revealed that transport of inorganic carbon increased the rate of O2 photoreduction. Hence, O2 could serve as an electron acceptor to allow oxidation of Qa even in the absence of CO2 fixation. 1 Supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC) to D. T. C. and an NSERC postdoctoral fellowship to G. S. E. This content is only available as a PDF. © 1988 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)

Brock, Thomas G.; Kaufman, Peter B.

doi: 10.1104/pp.88.1.10pmid: 11537432

Abstract Starch in pulvinus amyloplasts of barley (Hordeum vulgare cv Larker) disappears when 45-day-old, light-grown plants are given 5 days of continuous darkness. The effect of this loss on the pulvinus graviresponse was evaluated by following changes in the kinetics of response during the 5-day dark period. Over 5 days of dark pretreatment, the lag to initial graviresponse and the subsequent half-time to maximum steady state bending rate increased significantly while the maximum bending rate did not change. The change in response to applied indoleacetic acid (100 micromolar) plus gibberellic acid (10 micromolar) without gravistimulation, under identical dark pretreatments, was used as a model system for the response component of gravitropism. Dark pretreatment did not change the lag to initial response following hormone application to vertical pulvini, but both the maximum bending rate and the half-time to the maximum rate were significantly reduced. Also, after dark pretreatment, significant bending responses following hormone application were observed in vertical segments with or without added sucrose, while gravistimulation produced a response only if segments were given sucrose. These results indicate that starch-filled amyloplasts are required for the graviresponse of barley pulvini and suggest that they function in the stimulus perception and signal transduction components of gravitropism. 1 Supported by a National Aeronautics and Space Administration (NASA) Research Associate Award to T. G. B. and NASA grant NAGW-34 to P. B. K. This content is only available as a PDF. © 1988 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)

Gerbling, Heidrun; Gerhardt, Bernt

doi: 10.1104/pp.88.1.13pmid: 16666252

Abstract Peroxisomes from mung bean (Vigna radiata L.) hypocotyls catalyze, in the presence of branched-chain 2-oxo fatty acid, CoASH and NAD, the release of CO2, and the formation of NADH and acyl-CoA. The acyl-CoA contains one carbon atom less than the branched-chain 2-oxo fatty acid and serves as substrate for the peroxisomal acyl-CoA oxidase. CO2 release, NADH and acyl-CoA formation occur in 1:1:1 stoichiometry. For the first time the data demonstrate directly the oxidative decarboxylation of branched-chain 2-oxo fatty acids in higher plants and a location of this activity in the peroxisomes. 1 Supported by grants from the Secretary of the Department of Science and Research of the State of Nordrhein-Westfalen, FRG, and from the Fulbright Commission, USA. This content is only available as a PDF. © 1988 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)

Ngernprasirtsiri, Jarunya; Kobayashi, Hirokazu; Akazawa, Takashi

doi: 10.1104/pp.88.1.16pmid: 16666259

Abstract We have analyzed DNA methylation of plastid DNA from fully ripened red fruits, green mature fruits, and green leaves of tomato (Lycopersicon esculentum var. Firstmore). Essentially identical restriction profiles were obtained between chromoplast and chloroplast DNAs by EcoRI digestion. BstNI/EcoRII and HpaII/MspI are pairs of isoschizomers that can discriminate between methylated and unmethylated DNAs. These endonucleases produced different restriction patterns of plastid DNAs from tomato fruits compared to tomato leaves. Moreover, we have found from Southern blots that methylation was not detected in DNA fragments containing certain genes that are actively expressed in chromoplasts, whereas DNA fragments bearing genes that are barely transcribed in chromoplasts are methylated. 2 Recipient of the predoctoral student fellowship provided by the Hitachi Scholarship Foundation (Tokyo). 1 This is paper No. 72 in the series “Structure of Chloroplast Proteins.” The research was financially aided by a grant from the Ministry of Education, Science and Culture of Japan (Mombusho). This content is only available as a PDF. © 1988 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)

Otto, Beate; Grimm, Bernhard; Ottersbach, Peter; Kloppstech, Klaus

doi: 10.1104/pp.88.1.21pmid: 16666268

Abstract The levels of the mRNAs for light-inducible, nuclear-coded chloroplast proteins vary rhythmically in pea (Pisum sativum L.) plants either grown in a dark-light cycle or under constant light conditions. This has been observed for the early light-inducible protein, the light-harvesting chlorophyll a/b protein, and the small subunit of the ribulose-1,5-bisphosphate carboxylase. The mRNA levels are high in the morning, exhibit a minimum in the first half of the night, and increase again during the second half of the night. The amplitude of fluctuation is between 5- and 10-fold. A similar change in the mRNA abundance was found for four nuclear encoded heat-shock proteins of 18, 24, 26, and 30 kilodaltons. The ability of plants to transcribe heat-shock genes upon heat-shock for 2 hours varies through the day. The maxima for induction are found in the second half of the night and the morning. The minima are reached during the afternoon. The degree of fluctuation is between 3- and 5-fold. The levels of mRNAs for cytosolic as well as for plastid heat-shock proteins oscillate in parallel. 2 Present address: Carlsberg Research Laboratory, Kopenhagen, Denmark. 1 The authors are grateful for the generous financial support by the Deutsche Forschungsgemeinschaft, Bonn, FRG. This content is only available as a PDF. © 1988 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)

Ishii, Shigetaka

doi: 10.1104/pp.88.1.26pmid: 16666273

Abstract Callus cells of rice (Oryza sativa L.) that were actively dividing in suspension culture had lost the ability to divide during the isolation process of protoplasts. Factors influencing the protoplast viability were examined using highly purified preparations of cellulase C1, xylanase, and pectin lyase, which were essential enzymes for the isolation of protoplasts from the rice cells. The treatment of the cells with xylanase and pectin lyase, both of which are macerating enzymes, caused cellular damage. Xylanase treatment was more detrimental to the cells. Osmotic stress, cell wall fragments solubilized by xylanase, and disassembly of cortical microtubules were not the primary factors which damaged the rice cells and protoplasts. The addition of AgNO3, an inhibitor of ethylene action, to the protoplast isolation medium increased the number of colonies formed from the cultured protoplasts, although the yield of protoplasts was reduced by the addition. Superoxide radical (O2-) was generated from the cells treated with xylanase or pectin lyase. The addition of superoxide dismutase and catalase to the protoplast isolation medium resulted in a marked improvement in protoplast viability especially when the non-additive control protoplasts formed colonies with a low frequency. The addition of glutathione peroxidase and phospholipase A2, which have been known to reduce and detoxify lipid hydroperoxides in membranes, to the protoplast culture medium significantly increased the frequency of colony formation. These results suggested that some of the damage to rice protoplasts may be caused by oxygen toxicity. 1 Supported partially by the Research project entitled Research and Development of the Improvement of Bacterial and Plant Cells by Cell Fusion of the Food and Agriculture Research and Development Association (Japan). This content is only available as a PDF. © 1988 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)

Sela, Mordechai; Tel-Or, Elisha; Fritz, Eberhardt; Huttermann, Aloys

doi: 10.1104/pp.88.1.30pmid: 16666274

Abstract The storage and distribution of copper, cadmium, and uranium and their effects on ionic contents in roots and shoots of Azolla filiculoides has been studied by x-ray microanalysis. The relative content of copper was eightfold higher in the root than in the shoot, suggesting low mobility of this metal in Azolla plant. Cadmium relative content in the shoot was similar to its content in the root, hence its mobility was relatively high. The absence of significant uranium quantities in the shoot and its relative high content in the root suggest the immobility of this metal from Azolla root. Cadmium formed precipitates with phosphate and calcium in xylem cells of the shoot bundle and caused a two- to threefold increase in the content of phosphate in the root. Uranium in roots and cadmium in shoots were associated with calcium. All three treatments caused losses of potassium, chloride, and magnesium from Azolla roots. Accumulation of heavy metals in Azolla and their mobility from the root to the shoot can be correlated with damage caused by the loss of essential nutrients. 1 Supported by a research grant from the State of Niedersachsen, FRG. This content is only available as a PDF. © 1988 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)

Wolpert, T. J.; Macko, V.; Acklin, W.; Arigoni, D.

doi: 10.1104/pp.88.1.37pmid: 16666275

Abstract The structures of the toxins produced by Cochliobolus victoriae, victorin B, C, D, E, and victoricine, have recently been established. These toxins and modified forms of victorin C were tested for their effect on dark CO2 fixation in susceptible oat (Avena sativa) leaf slices. Half-maximal inhibition of dark CO2 fixation occurred with the native toxins in the range of 0.004 to 0.546 micromolar. An essential component for the inhibitory activity of victorin is the glyoxylic acid residue, particularly its hydrated aldehyde group. Removal of glyoxylic acid completely abolished the inhibitory activity of victorin, and the reduction of the aldehydo group transformed the toxin into a protectant. Conversion of victorin to its methyl ester resulted in diminution of inhibitory activity to 10% of the original activity of the toxin, whereas derivatization of the ε-amino group of the β-hydroxylysine moiety resulted in a decrease of inhibitory activity to 1% of that of victorin C. However, the derivatized toxin retained its host selectivity. In addition, the opening of the macrocyclic ring of the toxin drastically reduced the inhibitory activity. 1 Supported in part by grant 85-CRCR-1-1579 from the U.S. Department of Agriculture. This content is only available as a PDF. © 1988 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)

Hadjeb, Nouréddine; Gounaris, Ioannis; Price, Carl A.

doi: 10.1104/pp.88.1.42pmid: 16666276

Abstract Chromoplasts are a common differentiation state of plastids in which the photosynthetic apparatus is absent and carotenoids accumulate to high levels. As a first step toward the isolation of chromoplast-specific genes, we have examined plastids of the bell pepper, Capsicum annuum L., for the presence of chromoplast-specific proteins. Intact chromoplasts were isolated from mature fruits of C. annuum var Emerald Giant, Golden Cal Wonder, and DNAP VS-12 by differential centrifugation followed by isopycnic sedimentation in gradients of silica sols. The plastids were then fractionated into soluble and membrane components and the proteins analyzed by one- and two-dimensional gel electrophoresis using isoelectric focusing, sodium dodecyl sulfate, and sodium dodecyl sulfate-urea gels. Two polypeptides with M r of 35,000 and 58,000 accumulate to high levels in membrane fractions of chromoplasts of var Emerald Giant. These polypeptides are either not detectable or barely detectable in chloroplasts from immature fruits. Both polypeptides have been purified to near homogeneity. Yellow chromoplasts from var Golden Cal Wonder and red chromoplasts from var DNAP VS-12 contained the 35-kilodalton polypeptide, but not the 58-kilodalton species. 2 Present address: USDA, ARS, U.S. Regional Pasture Research Laboratory, University Park, PA 16802. 1 This work was supported by grants from the New Jersey Commission on Science and Technology, the DNA Plant Technology Corporation, and the Charles and Johanna Busch Memorial Fund. New Jersey Agricultural Experiment Station Publication No. D-01117-02-87, supported by State funds and by the United States Hatch Act. NH received fellowship support from the government of Algeria. IG was a postdoctoral fellow of the Charles and Johanna Busch Memorial Fund. This content is only available as a PDF. © 1988 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)