Influence of fusicoccin on the control of cell division by auxins.

An indirect stimulation of cell division by fusicoccin is demonstrated. The distribution of 2,4-dichlorophenoxyacetic acid molecules between Acer pseudoplatanus cells and their culture medium is strongly modified by a fusicoccin treatment, through the extracellular acidification induced by the toxin. As a consequence, a stimulation of cell division is observed when the intracellular auxin concentration is sufficiently increased to reach the threshold control level (Leguay JJ, J Guern 1977 Plant Physiol 60: 265-270).Independently of this indirect action on cell division, the number of cells per cluster is decreased and the volume of the cells increased in fusicoccintreated cells which show a typical enlargement response.