Field Properties and Ion Uptake of Wheat and Oat: Are They Expressed in the Modulatory Influences of Ions on Membrane ATPases?

Abstract

The CaATPase activities of microsomal fractions (10,000 g .times. 15 min - 30,000 g .times. 60 min) of roots from wheat (T. aestivum L. cv. Svenno) and oat (A. sativa L. cv. Brighton) are inhibited by HCO3- and Cl-; and there is no effect by K+ on the CaATPase. If the ATPase is activated by Mg2+ or by Mn2+ there is little or no effect by HCO3- or Cl-. In wheat preparations, there is again no effect of K+ on the Mg- or MnATPase(s); but in preparations from oat roots both the MgATPase and the MnATPase are strongly stimulated by K+. A relation between MgATPase and K transport is normally accepted, and the difference between wheat and oat could reflect different strength of coupling between energy (ATPase) and carrier for K; with the strong coupling in oat as one of the biochemical adaptations that makes oat functionable as a crop plant on much more acidic soils than wheat. Regulation of anion transport should be a general problem; and alternative hypotheses are presented for how CaATPase may be influenced if a connection with anion transport is assumed. Unity in principles may well be compatible with variation in the specific biochemical solutions of transport problems; and the biochemical solution may, in turn, be one of the factors that determine the ecological possibilities of an organism.