ISSN 10214437, Russian Journal of Plant Physiology, 2012, Vol. 59, No. 1, pp. 59–64. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © D.I. Bashmakov, N.A. Pynenkova, K.A. Sazanova, A.S. Lukatkin, 2012, published in Fiziologiya Rastenii, 2012, Vol. 59, No. 1, pp. 67–73.
Due to natural causes and industrial progress, glo
bal changes in the environment are occurring. Pollu
tion with stable toxic components such as heavy met
als (HM) is especially dangerous for plants . The
effects of excess HM include the delayed seed germi
nation, growth inhibition, and metabolic dysfunctions
in plant organisms [2, 3]. The primary effects of HM,
occurring at the cellular and subcellular levels, lead to
formation of reactive oxygen species (ROS) and oxi
dative stress [1, 4, 5].
Reactive oxygen species are involved in all stress
reactions of plant cells. Superoxide anion is the most
important ROS; it directly oxidizes macromolecules
and acts as a source of other longlived ROS [6, 7].
Lipid peroxidation, structural damage and inactiva
tion of proteins, as well as DNA mutations are typical
consequences of ROS action . Oxidative processes
normally occur in cell compartments, where their rate
is restricted by the protective antioxidant system .
This system comprises defense enzymes and low
molecularweight substances, such as carotenoids .
It is known that carotenoids perform their antioxidant
role primarily by inhibiting singlet oxygen, although
they can also neutralize other ROS .
Considering that biologically active compounds
can change plant responses to stress factors, it seems
feasible to increase plant resistance to HM by treating
them with growth regulators [9, 10]. The pretreatment
of cucumber seedlings with Thidiazuron, an artificial
compound with cytokininlike activity, fully or partly
prevented the electrolyte leakage from cotyledon
leaves under stress induced by HM (Pb and Cu), dem
onstrating the increase in plant resistance to stress fac
tors . In maize seeds treated with Thidiazuron and
kinetin (analog of natural cytokinin), the negative
effects of HM (zinc and nickel) were alleviated: these
growth regulators improved growth characteristics,
reduced the electrolyte leakage, and elevated the
ascorbate peroxidase activity .
Recently a series of new compounds with high
cytokininlike activity has been developed. Treating
the cucumber seeds and seedlings with a new growth
regulator, Cytodef promoted seed germination at opti
mal and low temperatures, reduced chilling damage,
and improved productivity and fruit quality .
However, there are only scarce data that Cytodef can
influence plant resistance to HM . Therefore, we
studied the influence of Cytodef on oxidative status
parameters and antioxidant level in cucumber seed
lings. We supposed that the treatment of germinating
seeds with Cytodef might alleviate damage caused by
HMinduced oxidative stress. However, we considered
a possibility that plant responses to heavy metals and
associated oxidative damage may differ for various
HM species. Thus, we have set the following goals: (1)
to compare the influence of equimolar solutions of
) and nonessential (
heavy metals on the production of superoxide anion
lipid peroxidation rate, and carotenoid con
tent in cotyledon leaves of cucumber; (2) to elucidate
Effect of the Synthetic Growth Regulator Cytodef and Heavy Metals
on Oxidative Status in Cucumber Plants
D. I. Bashmakov, N. A. Pynenkova, K. A. Sazanova, and A. S. Lukatkin
Faculty of Biology, Ogarev Mordovian State University, Bol’shevistskaya ul. 68, Saransk, 430005 Russia;
Received January 21, 2011
—We studied the influence of a synthetic cytokininlike growth regulator (Cytodef) and heavy metal
, and Ni
—on generation of superoxide anion lipid peroxidation, and
carotenoids content in leaves of 7dayold cucumber plants (
L., cv. Izyashchnyi). In some
instances Cytodef reduced the toxicity of heavy metals: it mitigated the negative effect of metals on oxidative
processes and elevated the concentration of antioxidants (carotenoids).
Keywords: Cucumis sativus
, heavy metals, growth regulators, Cytodef, superoxide anion, lipid peroxidation,
carotenoids, oxidative stress.
: HM—heavy metals; MDA—malondialdehyde;
ROS—reactive oxygen species; TBA—thiobarbituric acid.