ISSN 10214437, Russian Journal of Plant Physiology, 2010, Vol. 57, No. 3, pp. 376–381. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © S.N. Batasheva, F.A. Abdrakhimov, G.G. Bakirova, E.V. Isaeva, V.I. Chikov, 2010, published in Fiziologiya Rastenii, 2010, Vol. 57, No.3, pp. 398–403.
The increased nitrate nutrition of plants is known
to inhibit assimilate export from leaves [1, 2], but the
mechanism of this inhibition is yet unknown. In
model experiments  it was shown that direct infu
sion of nitratecontaining salts into the apoplast is
accompanied by the decrease in
suppression of photoassimilate transport from the leaf,
and by changes in photosynthetic carbon metabolism
and ultrastructure of phloem companion cells.
Considering that the increased plant nitrate con
tent is favorable for nitric oxide generation from nitrite
through enzymatic and nonenzymatic pathways ,
we studied the influence of a nitric oxide donor,
sodium nitroprusside, on photosynthetic metabolism
and cell ultrastructure in common flax leaf blades.
MATERIALS AND METHODS
The common flax (
was excised at the end of the rapid growth period,
when its height was 65–70 cm, and sodium nitroprus
side (SNP) solution was fed into the shoot under the
Pa at concentrations of 50
M, and 1 mM as described in . After a 30min
infiltration period, the middle part of the shoot con
taining 10–11 leaves was placed into a photosynthetic
(0.03%) was supplied under
natural lighting (this shoot part served as a source of
Immediately or 3 h after 2min exposure to the
, the plant was cut and divided
into several parts: (1) the central
C source area,
(2) the part below the source, (3) the part above the
source, and (4) the apex. The plant part exposed to
in the assimilation chamber was divided
into leaves and stem. Following a 30s period after the
assimilation, all plant parts were fixed
simultaneously with boiling 80% ethanol.
In homogenized samples, the
C content was
determined. The ethanol–watersoluble fraction of
source leaves was analyzed with twodimensional
paper chromatography. The radioactivity of samples
and chromatographic spots, corresponding to labeled
photosynthates, was determined with a Delta300
scintillation counter (Tracor Analytic, United States).
Fixation and preparation of specimens for electron
microscopy was conducted according to standard
methods. We analyzed the cell structure after 30min
infiltration of the NO donor into plants. Ultrathin sec
tions were prepared with a microtome LKBIII (LKB,
Sweden). The samples were viewed with an electron
microscope JEM1200 EX (Japan).
All experiments were performed in 5–7 replicates.
Tables and figures represent mean values and their
standard errors. We discuss only those parameters that
differed at a confidence level of no less than 0.95.
Infusion of the NO donor SNP into the apoplast
led to the decrease in
assimilation. At SNP con
Effects of Sodium Nitroprusside, the Nitric Oxide Donor,
on Photosynthesis and Ultrastructure of Common Flax Leaf Blades
S. N. Batasheva, F. A. Abdrakhimov, G. G. Bakirova, E. V. Isaeva, and V. I. Chikov
Kazan Institute of Biochemistry and Biophysics, Kazan Research Center, Russian Academy of Sciences, ul. Lobachevskogo
2/31, P.O. Box 30, Kazan, Tatarstan, 420111 Russia;
Received February 13, 2009
—Solutions of sodium nitroprusside, a nitric oxide donor, were introduced at various concentrations
into common flax (
L.) shoots with the transpirational water flow. Sodium nitroprusside
and nitrate were found to exert similar effects on incorporation of
C into photosynthetic products, leaf cell
ultrastructure, and the export of assimilates from leaves. The results suggest that export of assimilates from
leaves might be regulated by the products of incomplete nitrate reduction and that regulation may involve the
Key words: Linum usitatissimum apoplast nitric oxide nitrate sodium nitroprusside assimilate transport
phloem ultrastructure photosynthesis
: SNP—sodium nitroprusside.