[The basipetal transport of [2-(14)C] abscisic acid in roots of intact seedlings of runner beans and its significance for root geotropism].

One h and 3 h after point source application of [2-(14)C] ABA to the upper side of geotropically stimulated root tips of intact seedlings of Phaseolus coccineus L. a weak downward lateral transport of radioactivity was observed. A clear upward lateral translocation, however, occurred when ABA was applied to the lower side of the root tip. Thus a uniform distribution of radioactivity was established in horizontal roots regardless of the site of the application point, while in upright roots the distribution was asymmetric. Six h after ABA injection radioactivity was uniformly distributed in both the vertical and horizontal root tips.