title: Stachyose in the cytosol does not influence freezing tolerance of transgenic Arabidopsis expressing stachyose synthase from adzuki bean.
abstract: We expressed the stachyose synthase from adzuki bean (Vigna angularis) in Arabidopsis thaliana, under the control of the constitutive CaMV 35S promoter. Transgenic lines had only trace amounts of stachyose under normal growth conditions but accumulated stachyose to similar levels as raffinose upon cold acclimation. Stachyose production did not alter the freezing tolerance of cold acclimated rosette leaves. Non-aqueous fractionation of sub-cellular compartments revealed that in cold acclimated plants, raffinose but not stachyose accumulated to a proportion higher than the compartment size fraction in the plastids. Since both oligosaccharides are synthesized in the cytosol, this provides evidence that the so far unknown raffinose transporter of the Arabidopsis chloroplast envelope does not efficiently transport stachyose. The failure of stachyose to influence freezing tolerance in Arabidopsis supports the hypothesis that raffinose family oligosaccharides might function in protecting the thylakoid but not the plasma membrane during freezing.
authors.affiliation: Biologisches Institut, Abteilung Botanik, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
authors.forename: Dumitrita
authors.initials: D
authors.lastname: Iftime
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Hannah
authors.forename: Thomas
authors.initials: T
authors.lastname: Peterbauer
authors.forename: Arnd G
authors.initials: AG
authors.lastname: Heyer
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism*; D007887:Fabaceae / Q000201:enzymology* / Q000235:genetics; D005615:Freezing; D005700:Galactosyltransferases / Q000235:genetics / Q000378:metabolism*; D009844:Oligosaccharides / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D009844:Oligosaccharides; C005695:stachyose; D005700:Galactosyltransferases; C113913:galactinol -raffinose galactosyltransferase