ISSN 10214437, Russian Journal of Plant Physiology, 2014, Vol. 61, No. 3, pp. 355–359. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © N.M. Kaznina, A.F. Titov, L.V. Topchieva, Yu.V. Batova, G.F. Laidinen, 2014, published in Fiziologiya Rastenii, 2014, Vol. 61, No. 3, pp. 384–388.
Recent studies showed that transmembrane pro
tein transporters play the main role in the inflow and
movement of heavy metals (HMs) in plants [1, 2].
Thus, one group of transporters provides for metal ion
transport into the cytoplasm from the environment or
from intracellular compartments. They include, in
particular, representatives of CDF (
), NRAMP (
), and ZIP (
Zinc iron permease
families [3–5]. Another group of proteins is involved
in HM transport from the cytoplasm through the plas
malemma to conducting vessels or through mem
branes to the cell organelles. Proteins of HMA (
) family are among them [6, 7].
HMA proteins are related to ATPases of
and they differ in their localization in the cell and in
fulfilled functions [8–10]. For example, HMA2 and
HMA3 proteins have similar primary structure, but
HMA2 proteins are localized in the plasmalemma and
involved in the loading of HM ions, in particular cad
mium and zinc, into the conducting vessels and in
their transport from the roots to the stems , while
HMA3 proteins are localized in the tonoplast and
transport ions into the vacuole .
It should be noted that the majority of studies
devoted to HMA proteins and the expression of corre
sponding genes were performed on plantshyperaccu
mulators of HMs,
[13–15], and they all were focused on the
study of the mechanisms of hyperaccumulation and
hyperresistance. There are much less studies with
plants not belonging to hyperaccumulators, such as
those from the family Poaceae, although an increase in
the expression of
genes under the
influence of cadmium was detected in these species.
Thus, the level of transcripts of these genes increased
in the presence of metal in the roots and shoots of
wheat , rice , and barley . At the same time,
it was revealed that an increased expression of
genes in cereals (especially in rice) affected
the metal transport from the roots to the stems and
respectively the concentration of cadmium in the
seeds [7, 18].
The data presented above show the importance of
studying the role of HMA family transporters and cor
responding genes in the transport of cadmium ions in
plants and in the mechanisms of plant metal tolerance.
However, despite the obvious progress in this area,
there are still a number of unanswered questions, such
as a possible contribution of
to an increase in plant tolerance to cadmium, as well
as the impact of plant age on the expression of these
The Content of
in Barley Plants Treated with Cadmium
N. M. Kaznina, A. F. Titov, L. V. Topchieva, Yu. V. Batova, and G. F. Laidinen
Institute of Biology, Karelian Research Center, Russian Academy of Sciences,
Pushkinskaya ul. 11, Petrozavodsk, Karelia, 185910 Russia;
Received March 29, 2013
—The content of transcripts of
genes in roots and leaves of 3dayold (the
stage of seed germination) and 7dayold (the seedling stage) barley (
L., cv. Zazerskii 85)
seedlings in the presence of cadmium ions (100
M) was studied. Some organspecific and agerelated dif
ferences in the level of mRNAs of studied genes were identified. So, after a 4day exposure of plants to a solu
tion containing cadmium ions, the level of transcripts of
gene increased in the roots of 3dayold
seedlings, contributing to the sequestration of toxic ions in the vacuole. The level of
increased stronger in 7dayold seedlings, especially in the leaves, which apparently may lead to an increased
inflow of the metal ions in the phloem and to an activation of its translocation from the leaves to the roots.
The observed decrease in this gene transcripts in the roots contributed in its turn to a limitation of cadmium
transport to the shoots. A conclusion about the possible involvement of
gene in an increase of resis
tance of 7dayold barley plants to cadmium was drawn based on the comparison of gene transcripts and the
resistance of seedlings of different ages to this metal.
Keywords: Hordeum vulgare
, cadmium, protein transporters, levels of gene transcripts
: HM—heavy metals; HMA—heavy metal ATPase.