© 2007 Heron Publishing—Victoria, Canada
Spatial activity and expression of plasma membrane H+-ATPase in stem xylem of walnut during dormancy and growth resumption
Georges Alves (1), Melanie Decourteix (1), Pierrette Fleurat-Lessard (2), Soulaiman Sakr (1), Marc Bonhomme (3), Thierry Améglio (3), Andre Lacointe (3), Jean-Louis Julien (1), Gilles Petel (1) and Agnes Guilliot (1, 4)
1. UMR 547-PIAF, site des Cézeaux, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière cédex, France / 2. UMR 6161-CNRS, bâtiment Botanique, 40 avenue Recteur Pineau, 86022 Poitiers, France / 3. UMR 547-PIAF, site INRA de Crouelle, 234 avenue du Brézet, 63039 Clermont-Ferrand cédex 2, France / 4. Corresponding author (agnes.guilliot@univ-bpclermont.fr) / Received July 12, 2006; accepted December 4, 2006; published online July 3, 2007
Summary
Plasma membrane H+-ATPase (PM H+-ATPase) plays a key role in nutrient transport, stress responses and growth. To evaluate proton motive force differences
between apical and basal parts of acrotonic 1-year-old shoots of walnut (Juglans regia L. cv ‘Franquette’) trees, spatial and seasonal changes in PM H+-ATPase were studied in mature xylem tissues. During both the dormancy and growth resumption periods, and in both the apical
and basal parts of the stem, PM H+-ATPase activity showed positive correlations with the amount of immunodetectable protein. In spring, at the time of growth
resumption, higher activities and immunoreactivities of PM H+-ATPase were found in the apical part of the stem than in the basal part of the stem. In spring, the decrease in xylem sugar
concentration reflected the high sugar uptake rate. Our data suggest that PM H+-ATPase plays a major role in the uptake of carbohydrates from xylem vessels during growth resumption. These results are discussed
in the context of the acrotonic tendency of walnut shoots.
Keywords:
acrotony, apical bud, basal bud, bud break, Juglans regia, PM H+-ATPase, sugar uptake, vessel associated cell, xylem sap.
