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Hormonal Regulation of Ca 2+ Stimulated K + Influx and Ca 2+ , K + ‐ ATPase in Rice Roots: in vivo and in vitro Effects of Auxins and Reconstitution of the ATPase
Author(s) -
ERDEL LÁSZLÓ,
TÓTH ILDIKÓ,
ZSOLDOS FERENC
Publication year - 1979
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.1399-3054.1979.tb02612.x
Subject(s) - auxin , atpase , chemistry , enzyme , biochemistry , oryza sativa , stereochemistry , gene
The role of natural and synthetic auxins in regulation of ion transport and ATPase activity was studied in rice roots ( Oryza sativa L. cv. Dunghan Shah). In vivo treatment of seedlings with 2,4‐dichlorophenoxyacetic acid at 2 × 10 −6 M for a short period enhanced subsequent Ca 2+ stimulated K + influx and ATPase activity, while a longer treatment diminished both K + influx and ATPase activity. Indoleacetic acid at 10 −10 –10 −8 M induced ATPase activity. In in vitro experiments both 2,4‐dichloro phenoxyacetic acid and indoleacetic acid (10 −10 –10 −8 M ) stimulated Ca 2+ , K + ‐ATPase activity of a plasmalemma rich micro somal fraction from the roots. Acetone extracted ATPase preparations lost their activity. The enzyme regained its activity and its sensitivity towards ions (Ca 2+ + K + ) when reconstituted with phosphatidyl choline. Addition of auxins also indicated that the presence of the lipid was necessary in the interaction between the ATPase and auxins. Auxins and ions probably interact with the intact ATPase lipoprotein complex, which may possess a receptor site for the auxins, possibly as a sub unit.