ACCUMULATION OF C-14 FROM EXOGENOUS LABELED AUXIN IN LATERAL ROOT PRIMORDIA OF INTACT PEA-SEEDLINGS (PISUM-SATIVUM-L)

When [14C]indol-3yl-acetic acid was applied to the apical bud of 5-day old dwarf pea seedlings which possessed unbranched primary roots, a small amount of 14C was transported into the root system at a velocity of 11-14 mm h-1. Most of the 14C which entered the primary root accumulated in the young lateral root primordia, including the smallest detectable (20-30 mm from the primary root tip). In older (8-d old) seedlings in which the primary root bore well-developed lateral roots, 14C also accumulated in the tertiary root primordia. In contrast, little 14C was detected in the apical region of the primary root or, in older plants, in the apices of the lateral roots. © 1979 Springer-Verlag.