+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Carbohydrate uptake from xylem vessels and its distribution among stem tissues and buds in walnut (Juglans regia L.)



Carbohydrate uptake from xylem vessels and its distribution among stem tissues and buds in walnut (Juglans regia L.)



Tree Physiology 30(1): 89-102



Bud break pattern is a key determinant of tree architecture. The mechanisms leading to the precedence of certain buds over the others are not yet fully explained, but the availability of soluble sugars may play a significant role, especially those in the xylem sap at the onset of the growing period. Here, we measured carbon availability in the different tissues (bud, xylem and bark). To assess the capacity of buds to use the xylem sap carbohydrates, the fluxes between xylem vessels and parenchyma cells, bark and buds of walnut (Juglans regia cv 'Franquette') were measured during the rest period until bud break. This uptake capacity varies according to the temperature, the sugar and the position on the branch of the fragment studied. Between December and March, in xylem tissues, the active component of sucrose uptake was predominant compared with diffusion (90% of the total uptake), whereas the active component accounted for more moderate amounts in buds (50% of the uptake). The active uptake of hexoses took place belatedly (April) in xylem. The flow rates between xylem vessels and buds increased 1 month before bud break and reached 2000 microg sucrose h(-)(1) g DW(-)(1). Fluxes seemed to depend on bud position on the branch. However, this study strongly suggests that they were mainly dependent on the sink strength of the buds and on the sink competition between bud, xylem parenchyma and bark.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 051933934

Download citation: RISBibTeXText

PMID: 19955192

DOI: 10.1093/treephys/tpp103


Related references

Carbohydrate reserves and CO2 balance of hybrid walnut (Juglans nigra no. 23 x Juglans regia) plantlets during acclimatisation. Scientia Horticulturae 68(1/4): 207-217, 1997

On the dormancy of vegetative buds of walnut (Juglans regia). Comptes Rendus Hebdomadaires des Seances de l' Academie des Sciences, D 283(5): 499-502, 1976

Dormancy of vegetative walnut buds (Juglans regia L.). Comptes rendus hebdomadaires des seances Serie D Sciences naturelles: 0, 283 (5) 499-502, 1976

The role of growth regulators in the differentiation of Walnut buds (Juglans regia). Biol. Plant, 13: 5/6, 361-7, 1971

Indoleacetic acid induces xylem formation instead of rooting in walnut (Juglans regia L.) microcuttings. Plant Biosystems 135(1): 71-77, 2001

Dormancy of vegetative buds of walnut (Juglans regia) grown under different climatic conditions. Comptes Rendus Hebdomadaires des Seances de l' Academie des Sciences, France, D 284(23): 2351-2354, 1977

The precocious walnut form Juglans regia L. f. fertilis Petz. et Kirch. and its genetic connection with Juglans regia L. diffused in the culture. Dopovidi Natsional'noyi Akademiyi Nauk Ukrayiny 0(1): 104-107, 1996

Effect of root pruning on xylem exudation of seedling and graft success of walnut (Juglans regia L.). Anadolu 15(1): 44-48, 2005

JrSUT1, a putative xylem sucrose transporter, could mediate sucrose influx into xylem parenchyma cells and be up-regulated by freeze-thaw cycles over the autumn-winter period in walnut tree (Juglans regia L.). Plant, Cell and Environment 29(1): 36-47, 2006

Inheritance of the traits late leafing and fruiting from lateral buds in walnut (Juglans regia L.). Rivista di Frutticoltura e di Ortofloricoltura 54(1): 55-60, 1992

Dormancy of vegetative buds of walnut trees (Juglans regia L.) cultivated in different climatic conditions. Comptes rendus hebdomadaires des seances Serie D Sciences naturelles: 0, 284 (23) 2351-2354, 1977

Effect of a complete removal of the foliage on the onset of dormancy of walnut (Juglans regia) buds. Comptes Rendus Hebdomadaires des Seances de l' Academie des Sciences, D 286(10): 745-748, 1978