Relationship between cell division and endogenous auxin in synchronously-cultured tobacco cells

Abstract

In the cultured tobacco cell, we succeeded in obtaining a partial synchronization of cell division by a combination of pre-starvation, rhythmic light-dark pre-treatment and air tight pre-conditioning. The mitotic index increased during the light period according to the time interval after the end of pre-treatment, and reached its maximum (max=12%) at about 2.5 hr of irradiation, and about 80% of cells completed division 1.5 hr thereafter. During this period, IAA was biosynthesized in the cells, though these cells had been cultured in Murashige and Skoog's medium with 1 mg/l of 2,4-D as a growth substance. IAA was identified by paper chromatography, followed byAvena curvature test and combined gas chromatography-mass spectrometry. The time course of the increase and decrease in the amount of free IAA was parallel to that of the mitotic index. On the other hand, bound IAA increased later and decreased gradually after the end of cell division. Free IAA may have an important role in mitosis.