ISSN 10214437, Russian Journal of Plant Physiology, 2011, Vol. 58, No. 4, pp. 660–666. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © I.N. Demin, N.V. Naraikina, V.D. Tsedendambaev, I.E. Moshkov, T.I. Trunova, 2011, published in Fiziologiya Rastenii, 2011, Vol. 58, No. 4, pp. 574–581.
Oxygen, as a universal terminal electron acceptor
in the respiration process, is vitally necessary for func
tioning of essentially all living organisms, plants in
particular. In its basic molecular state, oxygen is
weakly active; but, as soon as an uncoupled electron
appears on its outer orbital, oxygen becomes
extremely reactive [1, 2]. The pool of interconverting
reactive oxygen species arising due to its electron exci
tation or redox reactions is usually called as ROS .
ROS effects on living organisms are determined by
their direct action on cell structures and ROSinduced
initiation of membrane lipid peroxidation (POL) via
the interaction with unsaturated fatty acids (FAs), and
this leads to strong damages to membrane structure
and functions. This is especially important in the case of
chloroplast and mitochondrion coupling membranes
and also the plasma membrane. Oxidative damage to the
plasmalemma results in the leakage of the cell con
tents, rapid cell dehydration, and death .
The disturbance of the electron transport chains
(ETC) in cell membranes contributes substantially in
ROS generation. In chloroplasts, ROS are produced in
both PSI (mainly with the involvement of ferredoxin)
and PSII (in the process of water photooxidation, for
example) [5, 6]. In mitochondria, formation is
related to the ETC functioning,despite the presence of
alternative oxidase, which prevents excessive ROS
generation . In the endoplasmic reticulum, super
oxide radical generation is determined by the activity
of cytochrome P450 and also by NADH oxidation
with involvement of the flavincontaining enzyme. In
the plasma membrane, oxidation of reduced pyridine
nucleotides (NADH) also results in the generation of
this radical .
At present it is known that ROS generation is a pre
cisely controlled process, which is very important for
normal functioning of living systems. However, many
changes in the environment (high light, water defi
ciency, temperature changes, treatment with herbi
Integration of the Cyanobacterial
12AcylLipid Desaturase Improves Potato Tolerance
to ParaquatInduced Oxidative Stress
I. N. Demin, N. V. Naraikina, V. D. Tsedendambaev, I. E. Moshkov, and T. I. Trunova
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, Moscow, 127276 Russia;
fax: 7 (499) 9778018; email: email@example.com
Received December 20, 2010
—The effect of potato plant (
L., cv. Desnitsa) transformation with the
sp. PCC 6803, encoding
12 acyllipid desaturase, on the development of plant tolerance
to oxidative stress was studied. To initiate oxidative stress, plants were treated with 1 mM paraquat; this treat
ment enhanced oxidative processes in both wildtype and transformed potato plants via the activation of
superoxide anionradical generation. This resulted in the activated oxidation of membrane lipids and the for
mation of a great amount of fatty acids with coupled double bonds (conjugated dienes, CD), further break
down of lipid molecules, and enhanced production of MDA in tissues of wildtype and transformed plants.
The characteristics of oxidative stress, including lipid peroxidation, were less pronounced in transformants as
compared with wildtype plants. After treatment with paraquat, activities of main antioxidant enzymes
(superoxide dismutase, catalase, and peroxidase) were much higher in wildtype than in transformed plants.
Thus, expression of inserted heterologous
12 acyllipid desaturase in potato plants resulted in
improved tolerance of transformants to oxidative stress due to the more efficient maintenance of stable cell
membrane structure functioning, and this permits prevention of electron “jump” to oxygen and, as a result,
of accelerated ROS generation. More developed and regularly arranged chloroplast membrane system in
transformants may also favor their improved tolerance.
Keywords: Solanum tuberosum
, transgenic plants,
12 acyllipid desaturase, low temperatures, oxidative
atress, lipid peroxidation, tolerance.
: CD—conjugated dienes; FA—fatty acid; NBT—
nitro blue tetrazolium; POL—peroxidation of lipids; PSI and
PSII—photosystem I and photosystem II; PUFA—polyunsatu
rated fatty acids; SOD—superoxide dismutase.