ISSN 1021-4437, Russian Journal of Plant Physiology, 2006, Vol. 53, No. 2, pp. 186–192. © MAIK “Nauka /Interperiodica” (Russia), 2006.
Original Russian Text © O.G. Polesskaya, E.I. Kashirina, N.D. Alekhina, 2006, published in Fiziologiya Rastenii, 2006, Vol. 53, No. 2, pp. 207–214.
Presently, close attention is paid to the elucidation
of the role of antioxidant systems in plant metabolism
and stress resistance [1–6]. Cell antioxidant systems
participate in defusing the reactive oxygen species
(ROS) that comprise singlet oxygen (
radical ( ), hydrogen peroxide (
hydroxyl radical ( ). These compounds are strong
oxidizing agents, and their possible accumulation in the
cell is very dangerous since they damage the structure
of membranes, proteins, and DNA [1–3, 6]. In a nor-
mally operating cell, there exists a dynamic equilibrium
between the formation of ROS and their elimination.
Carotenoids hinder generation of singlet oxygen in the
course of photosynthesis . Superoxide radical
formed because of operation of electron transport
chains involved in photosynthesis and respiration is
neutralized with the participation of superoxide dismu-
tases (SOD) and formation of peroxide [2, 6]. The elim-
ination of H
depends on a group of enzymes com-
prising catalase, peroxidases, and the enzymes of
ascorbate/glutathione cycle: ascorbate peroxidase
(APO) and glutathione reductase (GTR). Various iso-
forms of antioxidant enzymes operate in different cel-
lular compartments: chloroplasts, mitochondria, cyto-
sol, and peroxisomes where ROS are formed in the
course of certain redox reactions [1, 2, 4, 6–8].
Adverse conditions such as drought, low tempera-
ture, high concentrations of heavy metals, and many
other stress agents induce excessive production of ROS
and oxidative stress in plant cells [1, 4, 6, 9, 10]. At the
same time, the role of these dangerous molecules in the
stresses is twofold. In many cases, hydrogen peroxide
was shown to participate as a second messenger in the
signal transduction and to switch on the systems of
plant protection against stress, in particular, the induc-
tion of synthesis of antioxidant enzymes [3, 5, 9].
In addition to ionic unbalance and hyperosmotic
stress, high concentrations of NaCl induce oxidative
stress, which is accompanied by the destruction of
membranes and degradation of chlorophyll [11–17].
The extent of the oxidative stress is usually assessed by
the accumulation of malondialdehyde (MDA), a product
of peroxide oxidation of membrane lipids [6, 9, 15, 16].
Numerous papers showed that the plant cultivars nota-
ble for initially high antioxidant activity or the ability to
rapidly increase it were more resistant to oxidative
injury under stresses, including the stress induced by
salinization [6, 9, 12, 14–17]. At the same time, it is
Effect of Salt Stress on Antioxidant System of Plants
as Related to Nitrogen Nutrition
O. G. Polesskaya, E. I. Kashirina, and N. D. Alekhina
Department of Plant Physiology, Faculty of Biology, Moscow State University, Vorob’evy gory, Moscow, 119899 Russia;
fax: 7 (095) 939-4309; e-mail: email@example.com
Received April 12, 2005
—In plants of wheat (
L.) grown in the media with nitrate ( plants), ammonium
( plants), and without nitrogen (N-deﬁcient plants), the response to oxidative stress induced by the addi-
tion of 300 mM NaCl to the nutrient solution was investigated. Three-day-long salinization induced chlorophyll
degradation and accumulation of malondialdehyde (MDA) in the leaves. These signs of oxidative stress were
clearly expressed in and N-deﬁcient plants and weakly manifested in plants. In none of the treat-
ments, salinization induced the accumulation of MDA in the roots. Depending on the conditions of N nutrition,
salt stress was accompanied by diverse changes in the activity of antioxidant enzymes in the leaves and roots.
Resistance of leaves of plants to oxidative stress correlated with a considerable increase in the activities
of ascorbate peroxidase and glutathione reductase. Thus, wheat plants grown on the -containing medium
were more resistant to the development of oxidative stress in the leaves than those supplied with nitrate.
Key words: Triticum aestivum - nitrogen nutrition - salt stress - antioxidant enzymes
: APO—ascorbate peroxidase; CAT—catalase; GTR—
glutathione reductase; MDA—malondialdehyde; PO—peroxidase;
ROS—reactive oxygen species; SOD—superoxide dismutase.