Plant cell suspension cultures as model systems for investigating growth regulating compounds.

Several plant growth regulators were investigated for their activity in cell suspension cultures of Glycine max, Gossypium hirsutum and Zea mays. The effect on the growth of the cell cultures was traced by means of cell counting and determining packed cell volume and turbidity of the suspensions. The growth retardant 5-(4-chlorophenyl)-3,4,5,9,10-pentaaza-tetracyclo-5,4,10(2,6) ,0(8,11)-dodeca-3,9-diene (NDA) and, to a slightly lesser extent, ancymidol proved to be the compounds with the greatest inhibitory action on cell division growth of all three cell cultures. In the case of cotton this effect was accompanied by increased synthesis and secretion of cell-wall material. Staining methods showed that, especially in the case of NDA, a high percentage of cells could be considered as viable, and showed thus that NDA inhibits the cell division process while the cells remain metabolically active. The effects of 1,1-Dimethyl-piperidiniumchloride (DPC), a genuine growth retardant of cell propagation, and, with less efficiency, N-trimethyl-(β-chloroethyl)-ammoniumchloride (CCC) in cotton, the triazole LAB 117 682 in soybean and maize, and, to a lesser extent, (2-isopropyl-5-methyl-4-trimethyl-ammoniumchloride)-phenyl-l-piperidiniumcarboxylate (AM0-1618) in soybean can be regarded as species-specific. Otherwise, CCC and particularly daminozide exhibited no action at the concentrations used. A comparison of the data from hydroculture studies with soybean and maize seedlings showed considerable agreement with the effectiveness of the substances in the corresponding cell cultures. Thus, cell cultures can be used to identify and screen substances with growth-influencing activity, and may also offer new ways to elucidate the mode of action of plant growth regulators.