title: Sulfite oxidase protects plants against sulfur dioxide toxicity.
abstract: The gaseous pollutant SO(2) readily reacts with water to form sulfite that impacts deleteriously on animal and plant health. By modulating the level of sulfite oxidase (SO) that catalyzes the transformation of sulfites to the non-toxic sulfate, we show that Arabidopsis and tomato plants can be rendered resistant or susceptible to SO(2)/sulfite. Plants in which sulfite oxidase expression was abrogated by RNA interference (RNAi) accumulated relatively less sulfate after SO(2) application and showed enhanced induction of senescence and wounding-associated transcripts, leaf necrosis and chlorophyll bleaching. In contrast, SO overexpression lines accumulated relatively more sulfate and showed little or no necrosis after SO(2) application. The transcript of sulfite reductase, a chloroplast-localized enzyme that reduces sulfites to sulfides, was shown to be rapidly induced by SO(2) in a sulfite oxidase-dependent manner. Transcripts of other sulfite-requiring enzymatic activities such as mercaptopyruvate sulfur transferases and UDP-sulfoquinovose synthase 1 were induced later and to a lesser extent, whereas SO was constitutively expressed and was not significantly induced by SO(2). The results imply that plants can utilize sulfite oxidase in a sulfite oxidative pathway to cope with sulfite overflow.
authors.affiliation: The Jacob Blaustein Institute for Desert Research, The Albert Katz Department of Dryland Biotechnologies, Ben-Gurion University, PO Box 653, Beer Sheva 84105, Israel.
authors.forename: Galina
authors.initials: G
authors.lastname: Brychkova
authors.forename: Zongliang
authors.initials: Z
authors.lastname: Xia
authors.forename: Guohua
authors.initials: G
authors.lastname: Yang
authors.forename: Zhazira
authors.initials: Z
authors.lastname: Yesbergenova
authors.forename: Zhili
authors.initials: Z
authors.lastname: Zhang
authors.forename: Olga
authors.initials: O
authors.lastname: Davydov
authors.forename: Robert
authors.initials: R
authors.lastname: Fluhr
authors.forename: Moshe
authors.initials: M
authors.lastname: Sagi
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000201:enzymology; D001483:Base Sequence; D017931:DNA Primers; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000201:enzymology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050876:Sulfite Oxidase / Q000378:metabolism*; D013458:Sulfur Dioxide / Q000633:toxicity*
chemical_list: D017931:DNA Primers; D013458:Sulfur Dioxide; D050876:Sulfite Oxidase