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Reduction of nitrate in the perennial tissues of aerial parts of Alnus glutinosa
Author(s) -
Pizelle G.,
Thiery G.
Publication year - 1986
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1986.tb03364.x
Subject(s) - xylem , nitrate reductase , nitrate , alnus glutinosa , chemistry , transpiration , tungstate , transpiration stream , perennial plant , botany , bark (sound) , alder , horticulture , biology , biochemistry , ecology , photosynthesis , organic chemistry
In vivo nitrate reductase (NR, EC 1.6.6.1.) activity was measured in leaves, branches and trunk of field‐grown Alnus glutinosa (L.) Gaertn. All of the assayed tissues enzymatically reduced nitrate with a decreasing activity [μmol NO 2 − (g dry weight) −1 h −1 ] in the order: leaves > branch bark > inner branch tissues > trunk xylem. The NR activity of the various tissues of excised branches was inhibited by tungstate added to the transpiration stream. Part of the nitrate added to the feeding solution (0.2, 0.5 or 1 m M KNO 3 ) of excised branches disappeared during its transport via the transpiration stream in the perennial tissues. This disappearance was enzymatic since it was decreased by tungstate. No evidence was obtained for the presence of nitrate in natural xylem sap nor for a significant correlation between nitrate content of soil and leaf NR activity. These results indicate that in the field‐grown black alder, the nitrate not reduced in the roots could be reduced in the perennial tissues of aerial parts. Since the leaf NR activity does not reflect the actual in situ nitrate reduction, the existence of a constitutive NR activity in Alnus leaves is suggested.