ISSN 1021-4437, Russian Journal of Plant Physiology, 2009, Vol. 56, No. 4, pp. 470–479. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © N.I. Shevyakova, B.Ts. Eshinimaeva, N.V. Paramonova, Vl.V. Kuznetsov, 2009, published in Fiziologiya Rastenii, 2009, Vol. 56, No. 4, pp. 518–529.
Fe is a key plant micronutrient essential as electron
acceptor and donor for the functioning of electron-
transport chains of photosynthesis and respiration and
as a cofactor of many antioxidant enzymes (peroxidase
(PO), Fe-superoxide dismutase (Fe-SOD), and others).
Fe is also a component of the prostetic group of cyto-
chrome oxidases, Fe-S-proteins, and other proteins.
Recently, 43 genes responsible for Fe homeostasis
maintenance were identiﬁed in the rice genome . The
genes encoding FRO (Fe
dases), ZIP (Zn and Fe transporters), and Fe-containing
protein ferritin are among them.
Fe is one of the most abundant metals in soil and
plants, almost 100-fold exceeding the content of such
metals with varying valence as Zn, Cu, and Co, which
low amounts are also essential for plants .
In Nature, iron availability for plants depends
greatly on soil solution pH. Thus, in plants growing on
calceous and alkaline soils (pH > 7.0) under salinity,
iron ﬂow to aboveground organs is suppressed, which
induces its deﬁcit . At iron deﬁcit, the rate of photo-
synthesis declines, which is accompanied by leaf chlo-
rosis and yield drop . Iron deﬁcit is accompanied by
the development of “secondary” oxidative stress
because of a decrease in Fe-containing antioxidant
enzymes and proteins .
To maintain Fe homeostasis in the cells under con-
ditions of its declined availability, plants used two strat-
egies including functioning of traditional physiological
mechanisms. Strategy I is predominantly used by dicot-
yledonous plants growing on soils with high pH .
Alkaline pH inhibits activity of Fe-chelate reductase in
the root apoplast; this enzyme is required for reduction
chelated forms absorbed by the root and subse-
quent attachment of produced Fe
to transporters .
In this case, plants could cope with Fe deﬁcit by using
for its reduction the enzyme induced by low pH and
located in the plasma membrane. Such plant adjustment
is achieved by pH lowering by the
functioning in the rhizosphere . Another strategy
observed in rice plants is iron uptake as Fe
complex with phytosiderophores, which is easily
absorbed by the root; in this case, there is no necessity
in the extracellular iron reduction . However, in both
cases, Fe homeostasis in plants subjected to iron deﬁcit
was also dependent on enhanced expression of genes
encoding Fe-chelate reductases and speciﬁc proteins-
transporters. The gene encoding Fe
and some its homologues (for example,
involved in strategy I functioning were cloned and char-
acterized in arabidopsis, tomato, soybean, and rice .
Effects of Various Iron Supply on Oxidative Stress Development
and Ferritin Formation in the Common Ice Plants
N. I. Shevyakova, B. Ts. Eshinimaeva, N. V. Paramonova, and Vl. V. Kuznetsov
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, Moscow, 127276 Russia;
fax: 7 (495) 977-8018; e-mail: firstname.lastname@example.org
Received September 29, 2008
L. plants were grown from seeds in perlite. At the age of 4 weeks
(juvenile plants) or 6 weeks (adult plants), they were transferred on nutrient media with different Fe
brought in as Fe
–EDTA complex (pH 6.0): control, iron deﬁcit, and iron “excess”. Adult plants grown
in media differing in iron content were subjected to salinity (300 mM NaCl) during the last 8 days of growth.
Biochemical analyses were performed after plant ﬁxation in liquid nitrogen; simultaneously, the samples for
electron microscopy were taken. Different content of available Fe
in medium, especially under salinity con-
ditions, changed sharply the content of chlorophyll and proline, the rate of lipid peroxidation, the level of H
the activities of antioxidant enzymes in the leaves and roots, the number and sizes of plastoglobules, and ferritin
formation in plastids. Joint action of salinity and iron deﬁcit enhanced oxidative stress development, whereas
iron excess hampered oxidative reaction development, reduced the rate of lipid peroxidation, and increased the
chlorophyll content. At iron excess, plastoglobule lysis in plastids did not occur, their number and sizes
increased, and ferritin deposits appeared, whereas the latter were absent at iron deﬁcit.
Key words: Mesembryanthemum crystallinum - iron - salinity - ferritin - peroxidase - plastids - superoxide dis-
: PO—peroxidase; POL—peroxidation of lipids;