ISSN 10214437, Russian Journal of Plant Physiology, 2010, Vol. 57, No. 5, pp. 707–714. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © P.P. Pashkovskii, S.S. Ryazanskii, N.L. Radyukina, V.A. Gvozdev, Vl.V. Kuznetsov, 2010, published in Fiziologiya Rastenii, 2010, Vol. 57, No.5, pp. 756–764.
It is known that salinity, drought, unfavorable tem
peratures, UVB radiation, high light, heavy metals,
and other abiotic stressors induce generation of ROS
(superoxide, hydrogen peroxide, and hydroxyl radi
cal), which in turn activate antioxidant defense sys
tems . Stressinduced activation of antioxidant
enzymes suppresses oxidative stress and favors organ
ism survival under extreme conditions.
Superoxide dismutase (SOD) is one of the key
enzymes of the antioxidant system. At present, three
SOD isoforms are known containing ions of
; each of them can be represented
by several isoenzymes . As a rule, the plant responds
to stressors by total SOD activation; its activity could
be reduced after the attainment of a definite level of
oxidative stress. Total SOD activity is determined by
activities of its isoforms controlled at various expres
sion levels of genes encoding these isoforms [1, 2].
There are some data about transcriptional [3–5] and
posttranscriptional [6–8] regulation of SOD activity
in plants. Ca
, lowmolecular metabolites ,
glutathione , phytohormones , kinases and/or
phosphatases , and other factors can regulate SOD
activity. ROS evidently play especially important role
in this regulation. The presence of
tive to ROS in the promoter regions of SODencoding
genes  allows a supposition of ROS involvement in
the control of SOD activity at transcriptional level.
The involvement of ROS in the posttranscriptional
control of SODencoding genes is not essentially stud
ied. At the same time, it is established that one of the
important mode of posttranscriptional regulation of
gene activity is the mechanism of RNA interference
with the involvement of microRNAs (miRNAs).
MiRNAs is a class of regulatory RNAs 21–23 nt in
length. In complex with functional proteins, they reg
ulate differential genome expression on posttranscrip
tional level by direct degradation of complementary
mRNAs or by inhibition of their translation [15, 16].
At present, the hypothesis about miRNA role in the
realization of organism developmental program under
normal and stress conditions is considered [17, 18].
Thus, Sunkar et al.  demonstrated that, in
, three Cu/ZnSOD isoenzymes were
targets for MIR398; these isoenzymes were localized
in the cytosol, chloroplasts, and peroxisomes and were
tively. These authors observed a negative correlation
between the levels of MIR398 and mRNAs of
genes under the effects of various
MIR398 and Expression Regulation of the Cytoplasmic
Cu/ZnSuperoxide Dismutase Gene in
Plants under Stress Conditions
P. P. Pashkovskii
, S. S. Ryazanskii
, N. L. Radyukina
, V. A. Gvozdev
, and Vl. V. Kuznetsov
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences,
Botanicheskaya ul. 35, 127276 Moscow, Russia;
fax: 7 (495) 9778018; email: email@example.com
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
Received February 25, 2010
—In the salttolerant plant
, expression of microRNA from MIR398 family,
which regulated expression of superoxide dismutase (Cu/ZnSOD) in
tional level, was revealed. The effects of various salinity levels, illumination intensity, and UVB radiation on
MIR398 expression was demonstrated by Northernblot hybridization. These stressors changed the level of
MIR398 expression in roots and leaves in opposite directions, which indicates a possible stressdependent
transport of MIR398 over the plant. Under salinity stress and UVB irradiation, a negative correlation was
observed between expression of MIR398 and its target, mRNA of Cu/ZnSOD, one of the key enzymes of
plant antioxidant defense. Thus, MIR398dependent expression of
gene is characteristic of not only
glycophytes but also halophytes, being organunspecific and independent of abiotic stressors affecting the
Key words: Thellungiella halophila,
abiotic stress, superoxide dismutase, CSD, MIR398.
: miRNA—microRNA; SOD—superoxide dismu
tase; SSC—salinesodium citrate.