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Plasma membrane H + ‐ATPase activity is involved in adaptation of tomato calli to NaCl
Author(s) -
Kerkeb Loubna,
Donaire Juan Pedro,
RodríguezRosales María Pilar
Publication year - 2001
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 - 10.1034/j.1399-3054.2001.1110408.x
Subject(s) - vanadate , callus , subculture (biology) , atpase , chemistry , membrane , antiporter , biochemistry , lycopersicon , enzyme , biology , horticulture
A tomato ( Lycopersicon esculentum Mill. cv. Pera) callus culture tolerant to NaCl was obtained by successive subcultures of NaCl‐sensitive calli in medium supplemented with 50 m M NaCl. NaCl‐tolerant calli grew better than NaCl‐sensitive calli in media supplemented with 50 and 100 m M NaCl. Analysis of callus ion content showed a strong increase in Na + and Cl − both in NaCl‐tolerant and ‐sensitive calli grown in media containing NaCl for one subculture. Cells from NaCl‐tolerant calli showed a higher H + extrusion activity than those from NaCl‐sensitive calli grown for one subculture in the presence of NaCl. The inhibition of H + extrusion by NaCl‐sensitive cells was correlated with an inhibition of microsomal vanadate‐sensitive H + ‐ATPase (EC 3.6.1.35) and ATP‐dependent H + transport, while the stimulation of H + extrusion by cells tolerant to 50 m M NaCl was correlated with an increase in plasma membrane ATP‐dependent H + transport. The increase of ATP‐dependent H + extrusion in plasma membranes isolated from 50 m M NaCl‐tolerant calli was not a result of stimulation of a vanadate‐sensitive ATP hydrolytic activity or an increase in passive permeability to H + . Relative to NaCl‐sensitive calli, plasma membrane H + ‐ATPase from calli tolerant to 50 m M NaCl showed a lower K m for Mg 2+ ‐ATP. Our results indicate that tolerance of tomato calli to 50 m M NaCl increases the affinity of plasma membrane H + ‐ATPase for the substrate ATP and stimulates the H + ‐pumping activity of this enzyme without modifying its phosphohydrolytic activity.