Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Organic and inorganic sulfur transport in the xylem sap and the sulfur budget of Picea abies trees
    ( 1998)
    Köstner, B.
    ;
    Schupp, R.
    ;
    Schulze, E.-D.
    ;
    Rennenberg, H.
    Temporal changes in inorganic and organic sulfur compounds (sulfate, glutathione, cysteine methionine) were analyzed in xylem sap of 40-year-old Norway spruce (Picea abies (L.) Karst.) trees growing on acidic soils at a healthy and a declining stand in the Fichtelgebirge (North Bavaria, Germany). Studies were carried out (1) to quantify glutathione (GSH) transport in the xylem of spruce, (2) to study the significance of reduced sulfur versus sulfate (SO4(2-)) transport in the xylem, and (3) to compare total sulfur (S) transport in the xylem with the amount of foliar uptake of SO2 in an air-polluted environment. Glutathione was the main reduced S compound in the xylem ranging in concentration from 0.5 to 5 my mol 1(exp - 1). Concentrations of inorganic SO4(2-) in the xylem sap were up to 50 times higher than those of GSH ranging from 60 to 230 my mol 1(exp-1). During the growing season, concentrations of all S compounds in the xylem were highest in May (up to 246 my mol 1(exp -1) and de creased during summer and fall (up to 21 my mol 1(exp -1)). On average, SO4(2-) concentrations in xylem sap were 30 per cent higher at the declining site compared with the healthy site. Diurnal changes in organic S compounds were significant for GSH and cysteine with high concentrations during the night and low concentrations during the day. Diurnal changes in inorganic SO4(2-) concentrations were not significant. Xylem sap concentrations of SO4(2-) and cysteine were twice as high and GSH concentrations were tenfold higher in surface roots than in branches. At both sites, transport of organic S was (up to 3 per cent of total S) compared to transport SO4(2-) . Annual transport of total S in the xylem (SO4(2-) was the main component) ranged from 60 to 197 mmol tree(-1) year(-1) at the healthy site and from 123 to 239 tree(-1) year (-1) at the declining site. Although gaseous uptake of SO2 was estimated to be similar at both sites (38 mmol tree(-1) year(-1); Horn et al. 1989), the ratio b etween annual gaseous uptake of SO2 and transport of S in the xylem was 1:4 and 1:5 at the healthy and declining sites, respectively.
  • Publication
    Net uptake of sulfate and its transport to the shoot in spinach plants fumigated with H2S or SO2. Does atmospheric sulfur affect the 'inter-organ' regulation of sulfur nutrition?
    ( 1995)
    Herschbach, C.
    ;
    Kok, L.J. de
    ;
    Rennenberg, H.
    Spinach plants (Spinacea oleracea L. cv. Estivato) were grown on nutrient solutions under deficient, normal and excess sulfate supply. In both young and mature plants net uptake of sulfate and its transport to the shoot increased with increasing sulfate supply, but both processes proceeded at a higher rate in young as compared to mature plants. The relative sulfate transport, i.e. the relative amount of the sulfate taken up that is transported to the shoot, decreased with increasing sulfate supply. Apparently, net uptake of sulfate is not strictly controlled by the sulfur demand of the shoot, but xylem loading appears to counteract excess transport of sulfate to the shoot. Fumigation with H2S or SO2 reduced net uptake of sulfate by the roots in sulfur-deficient plants and absolute as well as relative sulfate transport to the shoot independent of the three sulfate levels supplied to the plant. At the same time thiol contents of the shoot and the root were enhanced by fumigation with H2S and SO2. These findings are consistent with the idea that thiols produced in the leaves can mediate demand-driven control of sulfate uptake by the roots and its transport to the shoot.
  • Publication
    Xylem sap composition of beech (Fagus sylvatica L.) trees. Seasonal changes in the axial distribution of sulfur compounds
    ( 1994)
    Rennenberg, H.
    ;
    Schupp, R.
    ;
    Glavac, V.
    ;
    Jochheim, H.
    During different phases of the annual growth cycle, xylem sap was collected from trunk segments of adult beech (Fagus s ylvatica L.) trees by the water displacement technique. Irrespective of the height of the trunk, both sulfate and reduced sulfur compounds were detected in the xylem sap throughout the year. Sulfate was the predominant sulfur compound in all samples analyzed. Its concentration in the xylem sap varied between 10 and 350 mymol l(-1), with highest concentrations in April, shortly before bud break. In contrast to other tree species, cysteine and not glutathione was the predominant thiol transported in the xylem sap of beech trees. The cysteine concentration ranged between 0. 1 and 1 mymol l(-1). As observed for sulfate, maximum cysteine concentrations were found in April. Apparently, both sulfate and cysteine transport contribute to the sulfur supply of the developing leaves. Seasonal changes in the axial distribution of cysteine and sulfate differed, indicating differenc es in the source-sink relations of these sulfur compounds. High, but uniform. xylem sap sulfate concentrations in April may originate from balanced sulfate uptake by the roots, whereas high cysteine concentrations in April, increasing with increasing height of the trunk, may originate in part from protein breakdown in the trunk. Reversal of the axial distribution of xylem sap cysteine in late summer-early fall to higher concentrations in the lower part of the trunk than in the upper part of the trunk suggests that the upper part of the trunk becomes a sink for cysteine as a result of the synthesis of storage proteins at this time of the year.
  • Publication
    Influence of glutathione (GSH) on net uptake of sulphate and sulphate transport in tobacco plants
    ( 1994)
    Herschbach, C.
    ;
    Rennenberg, H.
    Net uptake of sulphate by the roots, and its transport to the shoot was inhibited in intact tobacco plants by 1 h exposure of its roots to 0.1 or 1.0 mM GSH. The relative amount of sulphate taken up that was transported to the shoot was not affected by this treatment. Apparently, sulphate uptake, but not xylem loading of sulphate, was inhibited by GSH. Similar results were obtained when L-cysteine was used instead of GSH. As L-cysteine, mediated inhibition of sulphate, net uptake was counteracted by exposure of the roots to BSO, GSH synthesis seems to be required for inhibition of sulphate uptake by L-cysteine. However, exposure to 0.1 or 1.0 mM GSH did not result in an enhanced GSH level in roots or shoots. Also the cysteine contents remained unchanged. Small changes in metabolically active pools of GSH or cysteine seem to be responsible for the inhibition of sulphate uptake and its transport to the shoot. Flap-feeding of GSH to a mature leaf resulted in an inhibition of net uptake of sulphate by the roots and its transport to the shoot. These findings support the hypothesis that GSH produced in the leaves acts as a signal to control sulphur nutrition of plants.
  • Publication
    Thiol composition of a xylem-tapping mistletoe and the xylem sap of its hosts
    ( 1994)
    Rennenberg, H.
    ;
    Schupp, R.
    ;
    Schneider, A.
    Considerable amounts of low M(r) thiols were found in leaves, flowers and stems of the European mistletoe Viscum album (L). Leaf thiol contents were the highest so far reported for green tissue. Thiol composition was similar in all mistletoe organs analysed. Glutathione was the predominant low M(r) thiol of V. album independent of xylem sap thiol composition of the host. From the present findings it may be concluded that either cysteine removed from the xylem sap of the host is rapidly incorporated into glutathione in the endophytic system, or glutathione is selectively removed from the xylem sap of the host. The significance of de novo reduction of sulphate taken from the xylem sap of the host for the mistletoe's thiol composition and content remains to be elucidated.
  • Publication
    Growth and hydrogen sulfide emission of photoheterotrophic tobacco cells supplied with l-cysteine as sole sulfur source
    ( 1985)
    Grundel, I.
    ;
    Rennenberg, H.
    Growth of photoheterotrophic tobacco cells (Nicotiana tabacum L. var."Samsun") in suspension cultures is inhibited in the presence of 0.8 mM L-cysteine as sole sulfur source, when inoculated at densities up to 9.5 mg dry weight. Under these conditions, hydrogen sulfide is emitted in amounts increasing with increasing inoculation densities. An inoculum of 19 mg dry weight, however, enables a moderate growth of the cells (doubling time 178 h) while reducing the emission of hydrogen sulfide. Feeding of 0.4 mM L-leucine to the suspension did not only reduce hydrogen sulfide emission at all inoculation densities applied; it also caused exponential growth (doubling time 110 h) at inoculation densities of 9.5 mg and upwards. Initial and final rate of growth of tobacco cells supplied with L-cysteine as sulfur source increased, hydrogen sulfide emission decreased with increasing L-leucine concentrations in the medium. These effects are not specific for L-leucine, but are also observed when L-is oleucine, L-threonine, or L-valine were added to the suspensions. Support of growth and suppression of hydrogen sulfide emission by L-leucine is accompanied by a reduction of the initial as well as the final rate of uptake of L-cysteine by the cells. (IFU)
  • Publication
    Evidence for an intracellular sulfur cycle in cucumber leaves
    ( 1982)
    Filner, P.
    ;
    Rennenberg, H.
    ;
    Sekija, J.
    ;
    Wilson, L.G.