The Effect of Indol-3YL-Acetic Acid Concentration on Cycling and Quiescent Cells in the Apical Meristem of Excised Roots ofPisum SativumL.

Abstract

SUMMARYThe effects of various concentrations of IAA on root growth by elongation and on cell proliferation and quiescence in the apical mm of excised roots of Pisum sativum have been determined. Root elongation was suppressed by all of the concentrations of IAA (10−2, 10−8 and 10−6 M) investigated. The data obtained suggest, however, that in pea roots grown in IAA supplemented media, growth by elongation would be optimal when the concentration is about 10−10 M. The various aspects of meristematic activity examined in the apical meristem of the excised roots were almost identical in the controls, grown in the absence of IAA, and in those cultured in the presence of 10−12 M IAA. Increase in the level of IAA in the culture solution from 10−2 to 10−6 M, however, resulted in a progressive increase in the duration of the mitotic cycle, as measured from the curves recording the passage of labelled nuclei through mitosis, and a parallel increase in the duration of S. The durations of G1, G2 and mitosis were virtu...