Spatial activity and expression of plasma membrane H+-ATPase in stem xylem of walnut during dormancy and growth resumption.
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.
UMR 547-PIAF, site des Cézeaux, Université Blaise Pascal, 24 avenue des Landais, 63177 Aubière cédex, France.
Georges
G
Alves
Melanie
M
Decourteix
Pierrette
P
Fleurat-Lessard
Soulaiman
S
Sakr
Marc
M
Bonhomme
Thierry
T
Améglio
Andre
A
Lacointe
Jean-Louis
JL
Julien
Gilles
G
Petel
Agnes
A
Guilliot
D002241:Carbohydrates; D002462:Cell Membrane / Q000201:enzymology*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D018744:DNA, Plant; D018506:Gene Expression Regulation, Plant; D031324:Juglans / Q000201:enzymology* / Q000235:genetics; D008856:Microscopy, Fluorescence; D018547:Plant Stems / Q000201:enzymology*; D021381:Protein Transport; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018749:RNA, Plant; D012621:Seasons; D052584:Xylem / Q000166:cytology / Q000201:enzymology*
D002241:Carbohydrates; D018076:DNA, Complementary; D018744:DNA, Plant; D012333:RNA, Messenger; D018749:RNA, Plant; D006180:Proton-Translocating ATPases