1021-4437/01/4801- $25.00 © 2001
Russian Journal of Plant Physiology, Vol. 48, No. 1, 2001, pp. 95–99. Translated from Fiziologiya Rastenii, Vol. 48, No. 1, 2001, pp. 113–118.
Original Russian Text Copyright © 2001 by Balagurova, Akimova, Titov.
The investigation of plant resistance to an adverse
environment brought about the concept of speciﬁc and
unspeciﬁc responses of plants to different stress factors
[1–5]. The essence of this concept lies in the fact that
the action of some stress factor results in an increase in
the resistance not only to this factor but also to several
other stress factors [6–8]. Thus, heavy metals and salts
in contact with only the root system increase the heat
tolerance of leaves [8, 9]. Moreover, even a short-term
treatment of roots with potassium chloride was recently
shown to modify the cold and heat tolerance of leaf
cells . Thus, a local action of chemicals on roots
causes an unspeciﬁc increase in leaf resistance.
Unspeciﬁcity of leaf and root cell responses to the
effect of heat was established in the experiments
involving local heating of plants .
The objective of this work was to demonstrate the
possibility of an unspeciﬁc change in the stress resis-
tance of plant organs located at a considerable distance
from the site of the action of adverse chilling tempera-
ture. There are few published data on this effect. Mean-
while, such information is important both for under-
standing the mechanisms of the formation of an
increased stress resistance in the plant organs located at
a considerable distance from the stressed ones and also
for understanding the interaction between different
plant organs under stress conditions. In this relation, the
purpose of our experiments was the investigation of the
effect of local cooling of plant parts (root, shoot) on the
changes in different kinds of stress resistance in the
cells of cooled and nontreated organs at the initial
stages of chilling treatment.
MATERIALS AND METHODS
Winter wheat (
species, cv. Mironovskaya 808) and cucumber (
L., cold-sensitive species, cv. Almaatinskii 1)
seedlings were used in our experiments. The seedlings
were grown inside rolls of ﬁlter paper moistened with
Knop nutrient solution, pH 6.4, in a phytotron chamber
C, a relative humidity of 60–70%, an illuminance
of ca. 10 klx, and a 14-h photoperiod.
Shoots or roots of 7-day-old seedlings were main-
tained at 2
C (wheat) and 10
C (cucumber) at 60–70%
relative humidity and 10 klx light intensity for 7 h.
These temperatures are optimal for the hardening of
intact seedlings . Untreated plant organs were main-
tained at 25
C. A TZhR-02/–20 thermoelectric thermo-
stat (Interm, Russia) was used for maintaining the
required temperature around the root system. It was
installed in a phytotron chamber that maintained the
required air temperature.
Cotyledons and the main root of a cucumber seed-
ling as well as the ﬁrst leaf and the longest root of a
wheat seedling were used for assessing stress resis-
tance. The root segments to be analyzed were taken
The Effect of Local Cooling of Cucumber and Wheat Seedlings
on Various Kinds of Stress Resistance of Their Leaves and Roots
N. I. Balagurova, T. V. Akimova, and A. F. Titov
Institute of Biology, Karelian Research Center, Russian Academy of Sciences,
Pushkinskaya ul. 11, Petrozavodsk, Karelia, 185610 Russia;
fax: 7 (8142) 77-9810; e-mail: firstname.lastname@example.org
Received September 28, 1999
—Shoots and roots of wheat (
L., cold-resistant species) and cucumber (
L., cold-sensitive species) were chilled at 2
C or 10
C, respectively, for 7 h. The changes in cold, heat,
and salt resistance in treated leaf and root cells were recorded. Local cooling of the leaf resulted in an increase
of its cold and salt tolerance, but its heat tolerance remained unchanged. At the same time, cold tolerance of the
root slightly increased as a result of local cooling, but its heat and salt tolerance decreased. Cooling of the shoot
did not affect the cold and heat tolerance of root cells but caused a decrease in their salt tolerance. Finally, in
the leaf maintained at a normal temperature, there was an increase in all kinds of stress resistance as a result of
root cooling. We discuss the possibility of an unspeciﬁc change in stress resistance caused by metabolic shifts.
These shifts are induced by a signal, which is transmitted inside the plant into plant organs located at a consid-
erable distance from the chilled ones.
Key words: Triticum aestivum - Cucumis sativus - local cooling - resistance - leaf - root
—salt solution osmotic pressure lethal for
50% of cells; LT
—temperature lethal for 50% of cells.