title: Freezing tolerance by vesicle-mediated fructan transport.
abstract: Fructans are fructose-based polymers associated with freezing tolerance. They might act directly via membrane stabilization or indirectly by stimulating alternative cryoprotectants. Fructans and fructan biosynthetic enzymes, in general, are believed to be present in the vacuole. This paper draws particular attention to the surprising presence of fructans and fructan exohydrolase activity in the apoplast of cold-stressed plants. This observation raises questions concerning the origin of apoplastic fructans and suggests that fructans are transported to the apoplast by post-synthesis mechanisms, perhaps induced by cold. We propose a conceptual vesicle-mediated transport model for the movement of vacuolar fructans to the apoplast, where they could assist in stabilizing the plasma membrane.
authors.affiliation: Institute for Crop Production and Grassland Research, University of Hohenheim, D-70599 Stuttgart, Germany.
authors.forename: Ravi
authors.initials: R
authors.lastname: Valluru
authors.forename: Willem
authors.initials: W
authors.lastname: Lammens
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Claupein
authors.forename: Wim
authors.initials: W
authors.lastname: Van den Ende
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D001692:Biological Transport / Q000502:physiology; D005615:Freezing; D005630:Fructans / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism; D008954:Models, Biological; D010944:Plants / Q000201:enzymology / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
chemical_list: D005630:Fructans; D006026:Glycoside Hydrolases; C021512:levanase