1021-4437/03/5003- $25.00 © 2003
Russian Journal of Plant Physiology, Vol. 50, No. 3, 2003, pp. 301–304. Translated from Fiziologiya Rastenii, Vol. 50, No. 3, 2003, pp. 341–345.
Original Russian Text Copyright © 2003 by Shakirova, Bezrukova, Aval’baev, Fatkhutdinova.
Environmental stress factors induce substantial
changes in the plant-cell metabolism, and ABA plays a
key role in these changes [1–3]. ABA induces the syn-
thesis of more than dozen stress proteins, and the pro-
tective action is demonstrated for some of them [2–5].
At the same time, several normally present cell proteins
are also involved in plant defense responses, as indi-
cated by their stress-induced synthesis and accumula-
tion [6–8]. Wheat germ agglutinin (WGA), a typical
cereal lectin, may belong to these proteins, and ABA
induces the WGA gene expression [9, 10].
Although biological, physical, and chemical proper-
ties of WGA are well studied, its physiological role
remains obscure . In response to various stress fac-
tors, biotic (fungal pathogens ) and abiotic (drought
and osmotic shock , hyperthermia , or salinity
), the level of WGA in growing wheat plants
increased two- to sevenfold, and this increase was pre-
ceded by a sharp transient ABA accumulation. On the
basis of these data, it was proposed that WGA played
an important role in the establishing of ABA-controlled
unspeciﬁc defense responses .
It is worth noting that a stress-induced accumulation
of ABA and WGA in wheat plants subjected to various
stresses can occur relatively rapidly, for example,
within 1–2 h under salinity. This fact presumes that
ABA controls WGA accumulation not only at the tran-
scriptional level but also by activating its synthesis on
preformed mRNAs and/or its formation from precur-
sors present in wheat cells as demonstrated earlier [10,
17, 18]. At the same time, the cause for a sharp (almost
ﬁvefold) increase in the WGA content under salinity
 is not clear. What is the role of WGA in plant
defense responses? To answer this question, we carried
out the experiments with wheat plants treated with
WGA and NaCl.
The objective of this work was to investigate the
control mechanisms for WGA accumulation in wheat
seedling roots and the protective action of this protein.
MATERIALS AND METHODS
Four-day-old wheat (
L., cv. Sara-
tovskaya 29) seedlings were used. Seeds were surface-
sterilized with 96% ethanol and germinated for three
days in trays on ﬁlter paper moistened with tap water at
C, a 16-h photoperiod, and an illuminance of
15 klx. The endosperm was removed, and seedlings
were kept for another day on 2% sucrose in order to
eliminate the wounding effect . Thereafter, four-
day-old seedlings were placed onto 2% sucrose con-
taining 0.3 M NaCl. In some treatments, the inhibitors
of RNA and protein synthesis, 50 mg/l cordycepin or
10 mg/l cycloheximide, were added. The effects of
these inhibitor concentrations on ABA-induced WGA
accumulation in seedling roots were also studied. To
this end, four-day-old seedlings were transferred onto
the 2% sucrose solution containing 3.7
M ABA in the
presence or in the absence of the inhibitors. Control
seedlings were kept onto 2% sucrose.
The content of WGA was estimated in the samples
comprising ten seedlings or roots of ten seedlings by
using the ELISA technique, as described earlier .
Plant material was homogenized in liquid nitrogen, and
the lectin was extracted with 50 mM HCl for 1 h at
room temperature. After centrifugation, the supernatant
was neutralized with 1 M phosphate buffer, pH 7.2, and
Control Mechanisms of Lectin Accumulation
in Wheat Seedlings under Salinity
F. M. Shakirova, M. V. Bezrukova, A. M. Aval’baev, and R. A. Fatkhutdinova
Institute of Biochemistry and Genetics, Ufa Research Center, Russian Academy of Sciences,
pr. Oktyabrya 69, Ufa, Bashkortostan, 450054 Russia;
Received February 13, 2002
—Using the inhibitory analysis, we demonstrated that 0.3 M NaCl and 3.7
M ABA induced wheat
germ agglutinin (WGA) accumulation in 4-day-old wheat (
) seedlings under conditions of
suppressed transcription and translation owing to some rapid mechanisms controlling the level of this protein.
Exogenous WGA could protect wheat seedlings against salinity by preventing the salt-induced inhibition of
mitotic activity in the apical root meristem.
Key words: Triticum aestivum - wheat germ agglutinin - ABA - salinity - RNA and protein synthesis inhibitors
: MI—mitotic index; WGA—wheat germ aggluti-