Inhibition of ion accumulation in maize roots by abscisic acid.

An inhibition of root growth, a decrease in the amount of potassium (as (86)Rb) and phosphate ((32)P) accumulation by the root, and a partial depolarization of transmembrane electropotential were observed to develop with a similar time course and to a similar extent when intact maize (Zea mays L.) roots were treated with 10(-5) M abscisic acid (ABA). Potassium uptake was inhibited by ABA when excised, low-salt roots were bathed in KCl, KH2PO4, or K2SO4. ABA did not affect the ATP content of the tissues, the activity of isolated mitochondria, nor the activity of microsomal K(+)-stimulated ATPases.