ISSN 10214437, Russian Journal of Plant Physiology, 2011, Vol. 58, No. 6, pp. 1082–1089. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.B. Ivanov, 2011, published in Fiziologiya Rastenii, 2011, Vol. 58, No. 6, pp. 944–952.
Detection of toxicants in environment by chemical
methods is sometimes inefficient, as it is often
unknown precisely, which substances should be
detected. Therefore, the system of bioassays is widely
applied for the assessment of toxicity of samples taken
under natural conditions, for example, various water
samples, soil extracts, etc. In addition, bioassays are
used for toxicity assessment of various chemical sub
stances in the search for new drugs, pesticides, etc.
One of the widely applied tests is the assessment of
seed germination and seedling growth suppression,
especially the inhibition of root growth in the solutions
of tested compounds or samples taken from ambient
medium. This test has been long ago standardized by
American and European environmental control agen
cies  and used in vast number of studies [2–4]. In
particular, we have used this test over more than 40
years for the assessment of cytostatic activity of various
chemical substances: antibiotics, antimetabolites, var
ious organic substances, noble metal complexes,
heavy metal salts, and others. A total of more than
1000 various substances were studied [5–7].
On the basis of studied cellular characteristics of
root growth, we demonstrate here that, by the analysis
of changes in the root growth rate as dependent on the
time of their exposure to inhibitor solutions, it is pos
sible to establish the extent of substance action on cell
division or elongation. The usage of such simple anal
ysis allows finding potential cytostatics, mutagens,
and embryotoxic substances, which detection by more
precise methods demands timeconsuming and expen
sive investigations. In particular, using this approach, we
performed a directional synthesis of novel antitumor
platinum complexes, and corresponding patents were
registered in some countries .
In this lecture, we consider the basics of root usage
as test objects and demonstrate how the analysis of
root responses to various chemical substances and
other external factors allows the finding of mecha
nisms of root growth tolerance to various unfavorable
The roots have some advantages as test objects for
screening toxic chemical substances:
(1) Treatment of growing roots with the solutions of
tested substances is more natural and simple in com
parison with other plant organs;
(2) Tested substances penetrate the roots easier
than aboveground organs;
(3) Root cells are more sensitive to most toxicants;
this is determined firstly by a relatively high cell growth
and rapid division in the roots as compared with
aboveground organs and secondly by a short period of
cell growth and early initiation of root branching.
Now, we focus on the selectivity and specificity of
substance action, the problem that often escapes the
attention of the researchers.
Using the Roots as Test Objects for the Assessment
of Biological Action of Chemical Substances
V. B. Ivanov
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, Moscow, 127276 Russia;
fax: 7 (499) 9778018; email: firstname.lastname@example.org
Received February 12, 2011
—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 con
trolled 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 measure
ment 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.
: plant, growth, root, meristem, cell transition to elongation, lateral root formation, toxicity, cyto
statics, selectivity of inhibitor action.