Picomolar concentrations of tentoxin affect Mg2+‐ and Ca2+‐ATPase activities of plasma membrane vesicles from roots of winter wheat seedlings

Martin G. Klotz, A. Bérczi, L. Erdei, Bernd Liebermann

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Purified plasmalemma vesicles were isolated in the presence of 250 mM sucrose from roots of 14‐day‐old seedlings of winter wheat (Triticum aestivum L. Martonvásári‐8) by phase partitioning of salt‐washed microsomal fractions in a Dextran‐polyethylene glycol two‐phase system, and both Mg2+‐ and Ca2+‐ATPase activities were detected. Orthovanadate‐sensitive Mg2+‐ATPase activity associated with the inside of right side‐out plasmalemma (PM) vesicles (latency 98%) was inhibited 76% by 0.3 mM Ca2+, Ca2+‐dependent ATPase activity located partly on the inside and partly on the outside of plasmalemma vesicles (latency 47%) was not affected by Mg2+. Mg2+‐ATPase activity was inhibited by 68% and inhibition of Mg2+ activation by 0.3 mM Ca2+ partly disappeared in the presence of 10 pM tentoxin, a fungal phytotoxin. Mg2+‐ATPase activity remained inhibited up to 10 nM tentoxin while at 1 μM tentoxin Mg2+ activation was as high as without tentoxin. K+‐stimulation and vanadate inhibition was increased and decreased, respectively, by 100 pM‐10 nM tentoxin. Ca2+‐dependent ATPase activity was continuously increased by 1 pM‐10 nM tentoxin, but at 1 μM tentoxin the stimulation disappeared. The effects of pM tentoxin on plasma‐lemma Mg2+‐ATPase are discussed in relation to its influence on K+ transport in wheat seedlings.

Original languageEnglish
Pages (from-to)405-410
Number of pages6
JournalPhysiologia Plantarum
Issue number3
Publication statusPublished - 1989


  • Calcium‐ATPase
  • magnesium‐ATPase
  • plasmalemma
  • roots
  • tentoxin
  • Triticum aestivum
  • wheat

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science
  • Cell Biology

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