ISSN 10214437, Russian Journal of Plant Physiology, 2011, Vol. 58, No. 5, pp. 799–807. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © D.V. Tereshonok, A.Yu. Stepanova, Yu.I. Dolgikh, E.S. Osipova, D.V. Belyaev, G.R. Kudoyarova, L.B. Vysotskaya, B.B. Vartapetian, 2011, published in Fiziologiya Ras
tenii, 2011, Vol. 58, No. 5, pp. 681–690.
Field flooding during crop growing leads to root
hypoxia, and this causes plant early senescence mani
festing in leaf chlorosis, necroses, defoliation, growth
retardation, and yield loss . This phenomenon
could be related to a decrease in the cytokinin content
in tissues because this phytohormone is synthesized in
the root tips, which suffer from oxygen deficiency pri
marily because of blockage of aerobic metabolic pro
cesses. In fact, plant treatment with cytokinins delays
their senescence under stress conditions, at flooding in
particular [2, 3]. Nevertheless, the information from
the literature about the relationship between endoge
nous cytokinin levels and hypoxia tolerance is contra
dictory [4, 5]. A possible reason for this may be the
insufficient data on the dynamics of the various cyto
kinin species content during hypoxia. On the other
hand, most research is done on plants contrasting with
respect to flooding tolerance and belonging to differ
ent species and even genera and therefore different not
only with respect to stress tolerance but also in a num
ber of other features, making these models not quite
adequate [4, 5].
Transgenic plants with altered cytokinin level are a
convenient model for studying the role of cytokinins in
the plant defense responses. These plants may be
obtained by plant transformation with the
isopentenyl transferase, a key enzyme of cytokinin
, and this
was done on a model plant
Zhang et al.  and on wheat by us .
In the present work, transgenic wheat plants of the
first generation (
) carrying a bacterial
analyzed under the conditions of root flooding.
Among the goals were to confirm the presence and
expression of the
transgene, to measure plant
growth, yield, and the content of various cytokinins in
plants. It seemed important to compare the dynamics
activation and the corresponding response of
defense systems in untransformed control and trans
genic plants, because soil hypoxia, like other stresses,
activates ROS generation and, thus, induces the
changes in defense enzyme activities .
MATERIALS AND METHODS
The plant material.
The work was done on T
obtained from selfpollination of T
L., cv. Enita  carry
ing the gene of interest
for isopentenyl transferase,
a key enzyme of cytokinin biosynthesis, driven by the
cauliflower mosaic virus 35S promoter and the
gene for neomycin phosphotransferase driven by the
NOS promoter as a selective marker. The untrans
formed plants of this cultivar served as controls.
Seed germination and selection of kanamycin
resistant plants was done under sterile conditions. The
seeds were surfacesterilized in a cheesecloth bag for
30 min in a commercial bleach Belizna solution, fol
Effect of the
Gene Expression on Wheat Tolerance
to Root Flooding
D. V. Tereshonok
, A. Yu. Stepanova
, Yu. I. Dolgikh
, E. S. Osipova
, D. V. Belyaev
G. R. Kudoyarova
, L. B. Vysotskaya
, and B. B. Vartapetian
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, Moscow, 127276 Russia;
fax: 7 (499) 9778018; email: email@example.com
Institute of Biology, Ufa Research Centre, Russian Academy of Sciences, Ufa, Russia
Received January 31, 2011
—The effect of enhanced cytokinin synthesis due to expression of the
on plant tolerance to root flooding was studied. Transgenic wheat (
L.) plants car
gene were more tolerant to flooding than wildtype plants. The effect of transformation was man
ifested in the higher yield and less growth inhibition during flooding. The measurements of activities of anti
oxidant enzymes, superoxide dismutase and catalase, as well as MDA content during flooding revealed dif
ferences between wildtype and transgenic plants that correlated with their tolerance. These results point to
the protective role of cytokinins during wheat root flooding.
Keywords: Triticum aestivum, ipt
gene, cytokinins, root flooding, ROS, lipid peroxidation.
: CAT—catalase, SOD—superoxide dismutase,
TBARS—thiobarbituric acidreactive substances.