title: Symplastic connection is required for bud outgrowth following dormancy in potato (Solanum tuberosum L.) tubers.
abstract: To gain greater insight into the mechanism of dormancy release in the potato tuber, an investigation into physiological and biochemical changes in tuber and bud tissues during the transition from bud dormancy (immediately after harvest) to active bud growth was undertaken. Within the tuber, a rapid shift from storage metabolism (starch synthesis) to reserve mobilization within days of detachment from the mother plant suggested transition from sink to source. Over the same period, a shift in the pattern of [U-(14)C]sucrose uptake by tuber discs from diffuse to punctate accumulation was consistent with a transition from phloem unloading to phloem loading within the tuber parenchyma. There were no gross differences in metabolic capacity between resting and actively growing tuber buds as determined by [U-(14)C]glucose labelling. However, marked differences in metabolite pools were observed with large increases in starch and sucrose, and the accumulation of several organic acids in growing buds. Carboxyfluorescein labelling of tubers clearly demonstrated strong symplastic connection in actively growing buds and symplastic isolation in resting buds. It is proposed that potato tubers rapidly undergo metabolic transitions consistent with bud outgrowth; however, growth is initially prevented by substrate limitation mediated via symplastic isolation.
authors.affiliation: Unit of Plant Biochemistry, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK.
authors.forename: Roberto
authors.initials: R
authors.lastname: Viola
authors.forename: Jérôme
authors.initials: J
authors.lastname: Pelloux
authors.forename: Anke
authors.initials: A
authors.lastname: van der Ploeg
authors.forename: Trudi
authors.initials: T
authors.lastname: Gillespie
authors.forename: Nicola
authors.initials: N
authors.lastname: Marquis
authors.forename: Alison G
authors.initials: AG
authors.lastname: Roberts
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hancock
mesh_terms: D001692:Biological Transport; D004058:Diffusion; D005452:Fluoresceins / Q000032:analysis / Q000378:metabolism; D052585:Phloem / Q000378:metabolism; D031425:Plasmodesmata / Q000502:physiology*; D011198:Solanum tuberosum / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
chemical_list: D005452:Fluoresceins; C024098:6-carboxyfluorescein; D013395:Sucrose; D013213:Starch