Biopolymers and cell. 1999; 15 (5): 432 - 441

The phytohormone-mediated action of the synthetic regulators on cell extension growth in higher plants

Victoria A. Tsygankova, Vladimir N. Zayets, Larisa A. Galkina1, Yaroslav B. Blume

It was shown that the action of synthetic growth activators on growth and development of isolated «non-decapitated» embryonic axes was analogous to action on embryonic axes of the intact haricot bean seeds; for the 72-hours period size increase of the embryonic axes depended on incubative medium composition: distilled water< tutidine N-oxide~-6-methylthiouracil< (IAA). Growth and development of «decapitated» embryonic axes in the same media sharply differed from the growth of «non-decapitated» axes: distilled water > lutidine N-oxide - 6-methylthiouracil < (IAA). In the experiments with embryonic axes in both of which one cotyledon was preserved («monocotyledonous seedlings») size increase was identical to size increase of embryonic axes in intact haricot bean seeds, as in the case of «non-decapitated» and «decapitated» embryonic axes, and it also depended on the incubative medium composition: distilled water < lutidine N-oxide - 6-methylthiouracil < (IAA). Investigation of the fractional composition of new synthesized f>4CJ impulse labelled proteins using the method of one-dimensional PAG-etectrophoresis and gel fluorography approach showed that lutidine N-oxide intensifies the synthesis of all cellular proteins fractions with predominating increase of the synthesis of some high-molecular and low-molecular polypeptides, and 6-methylthiouracil intensifies the synthesis of only one polypeptide with molecular weight of 30 kDa. The data obtained are examined accordingly as evidence in favour of ideas, developing in our investigation about phytohormone-mediated action of the synthetic plant growth regulators and different-direction mechanisms growth activating action of lutidine N-oxide and 6-methylthiouraciL The scheme of phytohormone-mediated action of the synthetic regulators on cell extension growth in higher plants is proposed.