Trees, 2014, Vol.28(2), pp.399-411
Byline: Dorte Randewig (1), Domenica Hamisch (2), Monika Eiblmeier (1), Christian Boedecker (2), Jurgen Kreuzwieser (1), Ralf R. Mendel (2), Robert Hansch (2), Cornelia Herschbach (1), Heinz Rennenberg (1,3) Keywords: APR, Adenosine 5 -phosphosulfate reductase; Gas exchange; GSH, Glutathione; Sulfate; SO, Sulfite oxidase; Sulfur dioxide Abstract: Key Message The critical level for SO .sub.2 susceptibility of Populus x canescens is approximately 1.2 uL L .sup.-1 SO .sub.2 . Both sulfite oxidation and sulfite reduction and assimilation contribute to SO .sub.2 detoxification. Abstract In the present study, uptake, susceptibility and metabolism of SO.sub.2 were analyzed in the deciduous tree species poplar (Populus x canescens). A particular focus was on the significance of sulfite oxidase (SO) for sulfite detoxification, as SO has been characterized as a safety valve for SO.sub.2 detoxification in herbaceous plants. For this purpose, poplar plants were exposed to different levels of SO.sub.2 (0.65, 0.8, 1.0, 1.2 uL L.sup.-1) and were characterized by visible injuries and at the physiological level. Gas exchange parameters (stomatal conductance for water vapor, CO.sub.2 assimilation, SO.sub.2 uptake) of the shoots were compared with metabolite levels (sulfate, thiols) and enzyme activities [SO, adenosine 5 -phosphosulfate reductase (APR)] in expanding leaves (80--90 % expanded). The critical dosage of SO.sub.2 that confers injury to the leaves was 1.2 uL L.sup.-1 SO.sub.2. The observed increase in sulfur containing compounds (sulfate and thiols) in the expanding leaves strongly correlated with total SO.sub.2 uptake of the plant shoot, whereas SO.sub.2 uptake rate was strongly correlated with stomatal conductance for water vapor. Furthermore, exposure to high concentration of SO.sub.2 revealed channeling of sulfite through assimilatory sulfate reduction that contributes in addition to SO-mediated sulfite oxidation to sulfite detoxification in expanding leaves of this woody plant species. Author Affiliation: (1) Fakultat fur Umwelt und Naturliche Ressourcen (UNR), Institut fur Forstwissenschaften, Professur fur Baumphysiologie, Albert-Ludwigs-Universitat Freiburg, Georges-Kohler Allee 53/54, 79085, Freiburg, Germany (2) Institut fur Pflanzenbiologie, Technische Universitat Braunschweig, Humboldtstrasse 1, 38106, Braunschweig, Germany (3) King Saud University, PO Box 2454, Riyadh, 11451, Saudi Arabia Article History: Registration Date: 08/11/2013 Received Date: 23/10/2013 Accepted Date: 08/11/2013 Online Date: 27/12/2013 Article note: Communicated by W. Bilger. Electronic supplementary material The online version of this article (doi: 10.1007/s00468-013-0958-x) contains supplementary material, which is available to authorized users.
APR, Adenosine 5′-phosphosulfate reductase ; Gas exchange ; GSH, Glutathione ; Sulfate ; SO, Sulfite oxidase ; Sulfur dioxide
View full text in Springer (Subscribers only)