1021-4437/05/5205- © 2005
Russian Journal of Plant Physiology, Vol. 52, No. 5, 2005, pp. 664–667. Translated from Fiziologiya Rastenii, Vol. 52, No. 5, 2005, pp. 747–750.
Original Russian Text Copyright © 2005 by Popov, Orlova, Kipaikina, Serebriiskaya, Merkulova, Nosov, Trunova, Tsydendambaev, Los.
Membrane lipid composition is known to respond
rapidly to temperature lowering . Usually, the level
of FA unsaturation in membrane lipids changes ﬁrstly.
During low-temperature acclimation of frost-resistant
plants, the lipids enriched in linoleic acid are synthe-
sized , which prevents cold-induced lipid transition
from liquid-crystalline to solid gel phase. In addition,
as early as in the ﬁrst 15–20 min after chilling of win-
tering cereals, a desaturation of preexisting FAs of
membrane lipids occurs . In chilling-tolerant plants,
lipid phase transition was not also observed at a low
above-zero temperature because of increased relative
content of unsaturated FAs in them; therefore, mem-
branes remained functionally active within a wide
range of temperature .
A capability for cold acclimation of chilling-sensi-
tive plants is largely determined by their ability to syn-
thesize the unsaturated FAs, thus ﬂuidizing the lipid
bilayer and preventing lipids from cold-induced phase
separation [5, 6].
FA desaturases are enzymes that introduce double
bonds into FAs of membrane lipids and, therefore,
improve membrane tolerance to low temperatures.
Higher plant FA desaturases can be divided into the two
groups depending on their substrate: (1) soluble acyl-
ACP desaturases, which modify FAs bound to acyl-car-
rying protein, and (2) membrane-bound acyl-lipid
desaturases, which modify FAs within lipids .
It was believed previously that plant cells have only
soluble acyl-ACP desaturases that introduce the ﬁrst
double bond at
position, and thereafter, acyl-lipid
desaturases introduce additional double bonds. How-
ever, a new family of
9-desaturases was found in
plants, which are homologous to acyl-lipid
rases of cyanobacteria. It is now evident that the ﬁrst
double bond at
position exerting the major “ﬂuidiz-
ing” effect on FA chains may be introduced into the
FAs in their lipid-bound form [8, 9].
In this study we describe the effect of the gene for
9-desaturase of the cyanobacterium
introduced to tobacco on the lipid
metabolism and chilling tolerance of chilling-sensitive
MATERIALS AND METHODS
Experiments were performed on tobacco plants
transformed with the
gene for acyl-lipid
urase of the thermophilic cyanobacterium
The Effect of Tobacco Plant Transformation with a Gene
on Plant Chilling Tolerance
V. N. Popov, I. V. Orlova, N. V. Kipaikina, T. S. Serebriiskaya, N. V. Merkulova,
A. M. Nosov, T. I. Trunova, V. D. Tsydendambaev, and D. A. Los
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences,
Botanicheskaya ul. 35, Moscow, 127276 Russia;
fax: 7 (095) 977-8018; e-mail: email@example.com
Received January 11, 2005
—Tobacco plants with the introduced
gene for acyl-lipid
9-desaturase from the thermophilic
were cultivated on agar-solidiﬁed Murashige and Skoog nutrient
medium supplemented with ferulic acid and antibiotics at 22
C and a 16-h photoperiod. Control plants were
transformed with an empty pGA482 vector. The analysis of fatty acids (FAs) showed that, in transgenic plants,
the level of 16:0 and 18:0 FAs decreased substantially, whereas the levels of di- and trienoic FAs increased.
Transformed plants were more cold-tolerant. The tolerance to chilling was evaluated from electrolyte leakage
from tissues damaged by cold treatments and from the accumulation of a product of lipid peroxidation, malon-
dialdehyde. It was concluded that acyl-lipid
9-desaturase was actively expressed in transgenic tobacco plants
and converted stearic acid into oleic acid, thus producing a substrate for further synthesis of di- and trienoic
FAs. An increased proportion of polyunsaturated FAs in membrane lipids resulted in improved tobacco plant
tolerance to chilling.
Key words: Nicotiana tabacum - transgenic plants - acyl-lipid desaturase - fatty acids - chilling tolerance
: ACP—acyl-carrying protein; AOS—antioxidant
system; FA—fatty acid; MDA—malondialdehyde; POL—peroxi-
dation of lipids.