Hormonal control of endoreduplication in sugar beet (Beta vulgaris L.) seedlings growing in vitro.

The effect on endoreduplication in sugar beet (Beta vulgaris L.) seedlings of five plant hormones in MS medium, ethylene, 24-epibrassinolide (EBR), gibberellic acid (GA(3) ), kinetin and 1-naphthaleneacetic acid (NAA), as well as a combination of kinetin and NAA at two different concentrations, was studied using flow cytometry. Analyses of DNA content in nuclei of the root, hypocotyl and cotyledons of seedlings growing in vitro were performed during their early development, starting from when the root was 0.5-1.0 cm long until expansion of the first pair of leaves. The proportions of nuclei with different DNA contents were established and the mean C-value calculated. The presence of exogenous plant hormones changed endoreduplication intensity, although to different extents, depending on the organ and developmental stage. Ethylene and NAA stimulated the process, while EBR and kinetin suppressed it and GA did not clearly affect it.