title: Is there any 12C/13C fractionation during starch remobilisation and sucrose export in potato tubers?
abstract: The delta(13)C (carbon isotope composition) variations in respired CO(2), total organic matter, proteins, sucrose and starch have been measured during tuber sprouting of potato (Solanum tuberosum) in darkness. Measurements were carried out both on tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly (13)C-depleted compared with starch in tubers, suggesting that starch breakdown was associated with a small isotope fractionation. In sprouts, all biochemical fractions including sucrose were (13)C-enriched compared with source tuber-sucrose, suggesting that sucrose translocation from tuber to sprouts fractionated against (12)C. However, both apparent fractionations were explained by the consumption of (13)C-depleted carbon for respiration or growth that enriched in the (13)C sucrose molecules left behind. In addition, whole tuber sucrose is constantly composed of recent sucrose from starch breakdown and old sucrose associated with an inherited, slightly (13)C-depleted pool. We therefore conclude that any fractionation at either the starch breakdown or the sucrose translocation level is unlikely under our conditions.
authors: Univ Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, UMR 8079, Orsay cedex, F-91405, France.
authors: Florence
authors: F
authors: Maunoury-Danger
authors: Camille
authors: C
authors: Bathellier
authors: Julien
authors: J
authors: Laurette
authors: Chantal
authors: C
authors: Fresneau
authors: Jaleh
authors: J
authors: Ghashghaie
authors: Claire
authors: C
authors: Damesin
authors: Guillaume
authors: G
authors: Tcherkez
mesh_terms: D001692:Biological Transport; D002244:Carbon / Q000032:analysis* / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis* / Q000378:metabolism; D035281:Plant Tubers / Q000737:chemistry / Q000378:metabolism; D011198:Solanum tuberosum / Q000737:chemistry / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D013395:Sucrose; D002244:Carbon; D013213:Starch