title: Identification of a new sucrose transporter in rye-grass (LpSUT2): effect of defoliation and putative fructose sensing.
abstract: Rye-grass fast regrowth after defoliation results from an efficient mobilization of C reserves which are transported as sucrose towards regrowing leaves, and which can be supported by one or several sucrose transporters (SUTs) like LpSUT1. Therefore, our objectives were to isolate, identify, characterize and immunolocalize such sucrose transporters. A protein (LpSUT2) showing a twelve spanning trans-membrane domain, extended N terminal and internal cytoplasmic loop, and kinetic properties consistent with well-known sucrose transporters, was isolated and successfully characterized. Along with LpSUT1, it was mainly localized in mesophyll cells of leaf sheaths and elongating leaf bases. These transporters were also found in parenchyma bundle sheath (PBS) cells but they were not detected in the sieve element/companion cell complex of the phloem. Unlike LpSUT1 transcript levels which increased as a response to defoliation in source and sink tissues, LpSUT2 transcript levels were unaffected by defoliation and weakly expressed. Interestingly, sucrose transport by LpSUT2 was inhibited by fructose. LpSUT1 and LpSUT2 appeared to have different functions. LpSUT1 is proposed to play a key role in C storage and mobilization by allowing sucrose transport between PBS and mesophyll cells, depending on the plant C status. LpSUT2 could be involved in sucrose/fructose sensing at sub-cellular level.
authors.affiliation: Université de Caen Basse Normandie, UMR Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France; INRA UMR 950, Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Berthier
authors.affiliation: Université de Caen Basse Normandie, UMR Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France; INRA UMR 950, Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Meuriot
authors.affiliation: UMR 7267 CNRS-Université de Poitiers équipe PHYMOTS, Université Poitiers, Bât Botanique (B5), BP 633, 86022 Poitiers, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Dédaldéchamp
authors.affiliation: UMR 7267 CNRS-Université de Poitiers équipe PHYMOTS, Université Poitiers, Bât Botanique (B5), BP 633, 86022 Poitiers, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Lemoine
authors.affiliation: Université de Caen Basse Normandie, UMR Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France; INRA UMR 950, Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France.
authors.forename: Marie-Pascale
authors.initials: MP
authors.lastname: Prud'homme
authors.affiliation: Université de Caen Basse Normandie, UMR Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France; INRA UMR 950, Ecophysiologie Végétale, Agronomie and Nutritions NCS, F-14032 Caen, France. Electronic address: nathalie.noiraud-romy@unicaen.fr.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Noiraud-Romy
mesh_terms: D001692:Biological Transport; D005632:Fructose / Q000378:metabolism; D008129:Lolium / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D026901:Membrane Transport Proteins; D010940:Plant Proteins; C078729:sucrose transport protein, plant; D005632:Fructose
keywords: Defoliation; Lolium perenne L; Regrowth; Sucrose; Sucrose transporter; Sugar sensing