1021-4437/01/4806- $25.00 © 2001
Russian Journal of Plant Physiology, Vol. 48, No. 6, 2001, pp. 770–773. Translated from Fiziologiya Rastenii, Vol. 48, No. 6, 2001, pp. 886–889.
Original Russian Text Copyright © 2001 by Glinka, Protsenko.
During plant growth and development, the composi-
tion of cell walls changes considerably, and these
changes are caused to a great extent by the activity of
hydrolytic enzymes, including the pectolytic ones.
canhydrolase; EC 18.104.22.168) hydrolyzes the glycoside
bonds situated near the free carboxyl groups of pectin,
and it is one of the major enzymes involved in pectin
metabolism. PG excreted by phytopathogenic fungi
favors the penetration of the fungus in plant tissues .
Regulation of PG activity is realized to a great extent by
the polygalacturonase-inhibiting protein present in
plant cell walls .
PGIP has attracted the attention of many research-
ers, because PG plays a key role in processes important
for both plants themselves and humans using plant
PGIP was found in virtually all plant organs and tis-
sues. It was also isolated from suspension-cultured
plant cells [3–5] as well as from callus tissue . Vari-
ous plant tissues differ in their PGIP activity, and its
changes depend on the developmental stage and envi-
ronmental effects . In particular, this activity
changes during fruit maturation . PGIP is also
believed to be one of the factors of plant tolerance
towards fungal diseases, which hinders fungal penetra-
tion into the plant by inhibiting PG of the fungus .
However, the role of PGIP in plants is not clearly under-
stood, and its activity in potato tissues is not often
investigated [10, 11]. At the same time, the data con-
cerning PGIP activity in the course of potato plant
development can be used for improving the technology
of potato cultivation and storage and for increasing the
disease resistance of the potato. Potato tubers can be
used as a convenient model for investigating endoge-
nous processes, which enable us to record them over a
reasonably long period of time.
The present work was devoted to the analysis of
changes in the PGIP activity in potato tubers during
storage, including long-term storage, as well as in
leaves and stems during the vegetative season.
MATERIALS AND METHODS
, cv. Istrinskii) obtained
from the Moscow Branch of the All-Russian Institute of
Plant Industry was used in this work. Potato plants were
grown on the experimental plots of the Bach Institute of
Biochemistry according to a standard technology. PGIP
activity in leaves and stems was determined starting in
July. Undamaged, fully developed leaves from the mid-
dle story of an adult plant were used.
PGIP activity was determined in dormant tubers
(stored at 4
C) and in sprouting tubers and sprouts,
which were obtained when tubers were stored at room
C) for 19 months. An average sample
of plant material (50–100 g) was prepared for analysis.
To obtain a PGIP preparation, potato tissues were
homogenized, at the 1 : 2 (w/v) ratio, in 10 mM acetate
buffer, pH 5.2, containing 1 mM mercaptoethanol
(Sigma, United States) and 0.1% Na
. The homo-
genate was squeezed through the caprone tissue, and
Changes in the Activity of Polygalacturonase-Inhibiting Protein
during Potato Development
E. M. Glinka and M. A. Protsenko
Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky pr. 33, Moscow, 117071 Russia;
fax: 7 (095) 954-2732; e-mail: email@example.com
Received December 20, 2000
—The activity of a polygalacturonase-inhibiting protein was determined in growing potato plants and
in stored potato tubers. The activity in leaves was higher than in stems, and it decreased by the end of the veg-
etative season. During the dormancy period, the inhibitory activity in tubers also changed. In the sprouting
tubers, it was somewhat lower than in the nonsprouting ones, and, in sprouts, it was usually higher than in
tubers. Both the plant polygalacturonase and the polygalacturonase secreted by phytopathogenic fungi after
their penetration in plant tissues can serve as inhibitor’s targets. Therefore, the inhibitor seems to control the
resistance of plants to infection by particular pathogens, and this resistance is characteristic of deﬁnite devel-
Key words: Solanum tuberosum - polygalacturonase- inhibiting protein - development - disease resistance
: PGIP—polygalacturonase-inhibiting protein;
PG—polygalacturonase; RG—reducing group(s).