ISSN 1021-4437, Russian Journal of Plant Physiology, 2007, Vol. 54, No. 4, pp. 464–471. © Pleiades Publishing, Ltd., 2007.
Published in Russian in Fiziologiya Rastenii, 2007, Vol. 54, No. 4, pp. 526–533.
Salinity, which is generally detrimental to plant
growth, adversely affects plant metabolism and causes
important modiﬁcations in growth, development, and
gene expression of plants. Such modiﬁcations may lead
to the accumulation or depletion of certain metabolites,
resulting in the imbalance in the levels of a relatively
small set of cellular proteins, which could increase,
decrease, appear, or disappear after salt treatment .
Soil salinity imposes two types of stresses on plants.
The ﬁrst one is nutritional imbalance caused by saline
ions and low soil water potential in both uptake and
translocation processes. The second one is a toxicity
due to the high accumulation of
ions in the
cytoplasm . Salinity causes a combination of com-
plex interactions affecting plant metabolism or suscep-
tibility to injury . To avoid this adverse effect, plant
evolves a great variety of adaptive mechanisms, such as
osmotic adjustment, selective ion uptake, and cytoplas-
mic and vacuolar ion compartmentation . However,
the molecular basis of salinity tolerance of various
plant species has not been understood .
Several salt-induced proteins have been identiﬁed in
plant species . Pareek et al.  suggested that stress
proteins could be used as important molecular markers
for the improvement of salt tolerance using genetic
engineering techniques. However, proteins produced
under salt stress are not always associated with salt tol-
erance; consequently, using proteins as a salt tolerance
indicator depends on the nature of the plant species or
There are many reports showing that the protein pat-
tern changes are accompanied by the biological
changes in the adaptation process, which makes the
organism more ﬁt in the altered environment [8, 9].
However, protein changes do not always confer toler-
Protein Pattern Changes in Tomato under in vitro Salt Stress*
, A. A. Ehsanpour
, Q. T. Hoang
, and J. Sh. Shin
Department of Biology, Faculty of Sciences, Isfahan University, Isfahan, Iran;
School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
Received June 21, 2006
—The investigation of salt-induced changes in the proteome would highlight important genes because
of a high resolution of protein separation by two-dimensional gel electrophoresis (2-DE) and protein identiﬁ-
cation by mass spectrometry and database search. Tomato (
Mill.) is a model plant for
studying the mechanisms of plant salt tolerance. Seeds of tomato cv. Shirazy were germinated on water–agar
medium. After germination, seedlings were transferred to Murashige and Skoog nutrient medium supplemented
with 0, 40, 80, 120, and 160 mM NaCl. After 24 days, leaf and root samples were collected for protein extrac-
tion and shoot dry weight measurement. Alterations induced in leaf and root proteins under salt stress treat-
ments were studied by one-dimensional SDS-PAGE. Leaf proteins were also analyzed by 2-DE. With increas-
ing salt concentration in the medium, shoot dry weight decreased. SDS-PAGE showed induction of at least ﬁve
proteins with mol wts of 30, 62, and 75 kD in roots and 38 and 46 kD in leaves. On the 2-DE gel, more than
400 protein spots were reproducibly detected. At least 18 spots showed signiﬁcant changes under salt stress.
Three of them corresponded to new proteins, while six proteins were up-regulated and ﬁve proteins were down-
regulated by salt stress. In addition, salinity inhibited the synthesis of four leaf proteins. Ten spots were ana-
lyzed by matrix-assistant laser desorption/ionization-time of ﬂight (MALDI-TOF), which led to the identiﬁca-
tion of some proteins, which could play a physiological role under salt stress. The expression of new pro-
teins(enoyl-CoA hydratase, EGF receptor-like protein, salt tolerance protein, phosphoglycerate mutase-like
protein, and M2D3.3 protein) under salt stress indicates that tomato leaf cells respond to salt stress by changes
in different physiological processes. All identiﬁed proteins are somehow related to various salt stress responses,
such as cell proliferation.
Key words: Lycopersicon esculentum - two-dimensional electrophoresis - salt stress - proteome - SDS-PAGE
Abbereviations and designations:
CHAPS—Zwitterionic detergent; DTT—dithiothreitol; EGFR—
epidermal growth factor receptor; IEF—isoelectrofocusing; IPG—
immobilized pH gradient; MALDI-TOF—matrix-assistant laser
desorption/ionization-time of ﬂight; MS—Murashige and Skoog
nutrient medium; PGM—phosphoglycerate mutase; PMSF—phe-
nylmethylsulfonyl ﬂuoride; TFA—triﬂuoroacetic acid; WA—
*The text was submitted by the authors in English.