ISSN 10214437, Russian Journal of Plant Physiology, 2013, Vol. 60, No. 2, pp. 221–226. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © V.N. Popov, O.V. Antipina, E.A. Burakhanova, 2013, published in Fiziologiya Rastenii, 2013, Vol. 60, No. 2, pp. 214–220.
Plant viability under low temperatures is provided
by a complex of physiological processes that lead to
plant adaptation to changing environmental condi
tions. A possibility of plant adaptation to hypothermia
depends on the balance between key metabolic pro
cesses, especially on the character of carbon metabo
lism . One of adaptive responses to low temperature
is the accumulation of intracellular sugars capable of
improving plant tolerance to hypothermia due to (1)
osmotic activity reducing the intensity of ice forma
tion in the space; (2) cryoprotective effect on cell
membranes; and (3) metabolic action as a source of
energy and precursors for the synthesis of other pro
tective substances .
Using the main transport form of sugars – sucrose
as a carbon and energy source depends on the activity
of the hydrolytic enzyme invertase. While localized in
the cell wall and associated with it by ionic bonds acid
invertase plays an important role in the distribution of
watersoluble carbohydrates in plant organs and tis
sues . In addition to the regulation of source–sink
relations , cellwall invertase is involved in the
development of pollen  and seeds . The literature
contains a large amount of evidence on the participa
tion of the cellwall invertase in the development of
responses to infection with plant pathogens: fungi ,
viruses , and bacteria . But so far there is little
information on the possible role of cellwall invertase
in the hardening coldsensitive plants, for which pro
viding all organs and tissues with sufficient amount of
soluble carbohydrates is essential for lowtemperature
adaptation . This is possible only at a balanced work
of the photosynthetic apparatus and maintaining the
outflow of assimilates from source cells to the places of
their utilization and accumulation, i.e., to sinks .
In this connection, the objective of this work was
the attempt of elucidation of cellwall invertase role in
lowtemperature hardening of coldsensitive plants.
MATERIALS AND METHODS
Experiments were performed with coldsensitive
tobacco plants (
L., cv. Samsun).
Plans were propagated by cuttings and cultivated on
the mineral substrate (Perlite) in the chamber of the
phytotron at Timiryazev Institute of Plant Physiology
(RAS) at a temperature of
a 16h photope
riod, and an irradiance of 100
hardening was performed in the KBW240 climatic
chamber (Binder, Germany) at a 16h photoperiod
and an irradiance of 100
for 6 days.
Sixweekold plants were used in experiments. Plant
have 6–7 leaves (3–4 g) and stem height of 6–8 cm.
The weight of the root system was 1.25–1.50 g. In
plants subjected to hardening for 6 days at
characteristics remained unchanged. The content of
dry weight was 14% in leaves and 7% in roots; it was
not changed during hardening. In control unhardened
plants, slight shoot growth (by 1–2 cm) was observed.
Involvement of CellWall Invertase in LowTemperature Hardening
of Tobacco Plants
V. N. Popov, O. V. Antipina, and E. A. Burakhanova
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, 127276 Moscow, Russia;
fax: 7 (499) 9778018; email: firstname.lastname@example.org
Received April 25, 2012
—Specific features of lowtemperature hardening (6 days at 8
C) of coldsensitive tobacco plants
, cv. Samsun) related to changes in the cellwall invertase activity were studied. During
cold hardening, oppositely directed changes in this enzyme activity occurred in tobacco leaves and roots. In
the leaves, cellwall invertase was activated (approximately by 30%), the content of sugars increased (approx
imately by 25%), and the content of sucrose, the main transport form of sugars, in the apoplast reduced by
three times; all these changes indicate that assimilate outflow from leaves to roots was inhibited. In contrast,
in the root system, enzyme activity was decreased almost twice and the content of sugars in them was essen
tially unchanged. It is suggested that a strategy of lowtemperature adaptation of coldsensitive tobacco plants
aimed at creating the high cold tolerance of aboveground parts, even at the expense of the root system, which,
under conditions of native vegetation, is not practically exposed to damaging low temperatures.
Keywords: Nicotiana tabacum,
cellwall invertase, photosynthesis, sugars, cold tolerance