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 x 15 min 30,000 g X 60 min) of roots from wheat (Triticum aestivum L. cv. Svenno) and oat (Avena sativa L. cv. Brighton) are inhibited by HCO3 and Cr; 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 HCOj or CL. In wheat preparations, there is again no effect of K' on the Mgor MnATPase(s); but in preparations from oat roots both the MgATPase and the MnATPase are strongly stimulated by K'. A relation between MgATPase and potassium transport is normally accepted, and the difference between wheat and oat could reflect different strength of coupling between energy (ATPase) and carrier for potassium; 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. It is pointed out that unity in principles may well be compatible with variation in the specific biochemical solutions of transport problems; and that the biochemical solution may, in turn, be one of the factors that determine the ecological possibilities of an organism.