1021-4437/05/5203- © 2005
Russian Journal of Plant Physiology, Vol. 52, No. 3, 2005, pp. 381–387. Translated from Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 430–437.
Original Russian Text Copyright © 2005 by Rumyantseva, Sal’nikov, Lebedeva.
The cell surface plays a key role in regulation and
maintenance of plant life. Basic processes of plant
development, such as reception, recognition of patho-
gens and intercellular communications, cell extension
and differentiation, are intimately related to the struc-
ture and metabolism of the cell surface [1–4].
Cultured plant cells are one of the most convenient
models for studies of morphogenetic processes. Callus
cultures are advantageous compared to suspension cul-
tures for studying cell surface events, since the use of
calli allows researchers to eliminate such undesirable
phenomena as mechanical ﬂaking of surface cells and
washing of the secret. Calli are also more convenient to
observe the development of morphogenetic events in
time. It should be noted that information on changes in
callus surface during induction of morphogenetic pro-
cesses is scanty but urgently needed for elucidation of
successive events that precede visible formation of
buds, roots, and embryoids
, particularly in the
case when these structures are formed from the surface
cells of explant or callus.
The aim of our work was to study the structure of the
callus surface in
during the induction of morphogenesis.
MATERIALS AND METHODS
We used morphogenic callus of common buckwheat
Moench.), which has a dense-
globular structure . Callus cultures were obtained
from immature embryos as described earlier . The
callus cultures were maintained in a thermostat at
on the RX nutrient medium , which con-
tained the B5 salts  supplemented with 2 mg/l of thi-
amine, 1 mg/l pyridoxine, 1 mg/l nicotinic acid, 2 g/l of
casein hydrolyzate, sucrose (up to 2.5%), 0.8% agar,
and growth regulators: 2 mg/l 2,4-D, 0.5 mg/l IAA,
0.5 mg/l NAA, and 0.2 mg/l kinetin. Calluses were
transferred on a fresh medium every 4 weeks. Morpho-
genesis was induced on agarized RX medium lacking
growth regulators, under illuminance of 3 klx .
For preparation of histological sections the plant
material was ﬁxed with 2.5% glutaraldehyde on a phos-
phate buffer (pH 7.3) and postﬁxed with 1%
the same buffer. After dehydration in alcohols, acetone,
and propylene oxide, samples were embedded in the
Epon epoxy resin. Sections were made with an LKB-
8800 ultratome (LKB, Sweden). For light microscopy,
sections were stained with 1% methylene blue. Sam-
ples were photographed with a Jenamed microscope
(Carl Zeiss, Germany).
For scanning electron microscopy, ﬁxed samples
were critical-point-dried and then coated with gold in
vacuum. Samples were viewed under a SCAN-25S
scanning microscope (Jeol, Japan).
Nicotinic acid, casein hydrolyzate, 2,4-D, IAA,
NAA, methylene blue, Epon, and glutaraldehyde were
Structural Changes of Cell Surface in Callus
Moench. during Induction
N. I. Rumyantseva, V. V. Sal’nikov, and V. V. Lebedeva
Kazan Institute of Biochemistry and Biophysics, Kazan Research Center, Russian Academy of Sciences,
PO Box 30, Kazan, Tatarstan, 420111 Russia;
fax: 7 (8432) 38-7577; e-mail: firstname.lastname@example.org
Received April 5, 2004
—Scanning electron microscopy was used to study the structure of callus of
Moench. during induction of morphogenesis. It was found that transferring of callus on the medium lacking
growth regulators induced several simultaneous developmental programs: embryoidogenesis, rhizogenesis, and
gemmogenesis. The program of embryoidogenesis prevailed over the others. Various morphological structures
were found to appear on the callus surface in the following order: trichome (on the 2nd day), roots (the 2nd or
3rd day), embryoids (the 6th to 8th day), and buds (the 10th to 14th day). It was shown that morphogenesis is
preceded by loosening of the callus surface and by appearance of the secret on it. Possible functions of secretion
in the induction of the observed processes are discussed.
Key words: Fagopyrum esculentum - callus - cell surface - secretion - trichomes - morphogenesis
: AGP—arabinogalactan protein.