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

V A Tsygankova,V N Zayets,Ya B Blume,L A Galkina

doi:10.7124/bc.00053b

Abstract

It was shown that the action of synthetic growth activators on growth and development of isolated «поп-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 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 «поп-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 [XAC] impulse labelled proteins using the method of one-dimensional PAG-electrophoresis 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 differentdirection 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.

Highlights

In published works [1, 2 ] devoted to screening and peculiarity of the biological action of synthetic plants growth regulators we stated hy pothesis about mediated action of the synthetic acti vators through endogenous pool of phytohormones
It is known that the prominent role in mechanisms of cells growth by extension belongs both to auxin-dependent as well as gibberellin-dependent cell wall enzymes
In dicot plants such enzyme is 1 -* 4 ^-endoglucanase [3, 4 ]. In this case the cell wall elongation is controlled by growth hormone auxin

Summary

Introduction

In published works [1, 2 ] devoted to screening and peculiarity of the biological action of synthetic plants growth regulators we stated hy pothesis about mediated action of the synthetic acti vators through endogenous pool of phytohormones. In dicot plants (in which the xyloglucan sidechains are abundant components of hemicellulose matrix of cell wall) such enzyme is 1 -* 4 ^-endoglucanase [3, 4 ] In this case the cell wall elongation is controlled by growth hormone auxin,. In monocot plants (which contain 5 % xyloglucan in their cell wall; while the arabinogalactan sidechains are abundant components of hemicellulose matrix of cell wall) this role is carried out by dextranase enzyme (a-l,6-D-glucan-6-glucanohydrolase) [5 ]. This enzyme is known to be an auxin-dependent and its function comes to following: dextranase breaks down arabinogalactan crosslinks of the hemicellulose microfibrillar matrix of the cell wall with the release of arabinose and glucose. T h e breaking of these crosslinks will impart the necessary plasticity to the wall for cell extension to occur passively under the influence of intracellular osmotic pressure, formed by the vacuole

A PHYTOHORMONE-MEDIATED ACTION OF THE REGULATORS ON CELL

Materials and Methods

Results and Discussion