Using the roots as test objects for the assessment of biological action of chemical substances

A sound approach to the root usage as model objects for the assessment of biological activity of chemical substances and environmental stressors is suggested on the basis of the analysis of various inhibitor and radiation action on the root. It is analyzed on the cellular level, how steady growth is maintained under various stress action. Special attention is paid to the meristematic cell transition to elongation, which is controlled by the two groups of processes: the first ones determine the rate of cell proliferation and the second ones determine the cell life span in the meristem. The rate of cell proliferation is rather sensitive to various treatments; in contrast, the processes controlling the cell life span in the meristem are rather stable. It is shown that studying the kinetics of the root growth rate gives much more information than a single measurement of root length increment. A possibility of root usage for the search of efficient cytostatics is exemplified. The role of the quiescent center in growth resumption after various stressful treatments is considered.