1021-4437/04/5104- © 2004
Russian Journal of Plant Physiology, Vol. 51, No. 4, 2004, pp. 476–479. Translated from Fiziologiya Rastenii, Vol. 51, No. 4, 2004, pp. 529–533.
Original Russian Text Copyright © 2004 by Graskova, Romanenko, Vladimirova, Kolesnichenko.
The interaction between the pathogen and host plant
induces some changes in cell metabolism, primarily in
the enzyme activities, including that of peroxidase .
Peroxidase is one of abundant enzymes with a broad
action spectrum. It is involved in substrate oxidation,
cell-wall ligniﬁcation, photosynthesis, respiration, and
growth regulation. An enhanced peroxidase activity
was also demonstrated during pathogenesis [1–3].
Therefore, peroxidase is believed to be one of the most
important factors of the plant biochemical defense
against pathogenic microorganisms, which is actively
involved in the self-regulation of plant metabolism after
infection [1, 2].
(Cmc) is known to induce potato tuber ring rot and
potato shoot wilting . The infection of various potato
cultivars, when grown under axenic conditions, with
the virulent 5369 strain was shown to activate peroxi-
dases in host plants .
 demonstrated that the infection of
lower tobacco leaves with tobacco mosaic virus acti-
vated peroxidase in the leaves positioned higher along
the stem. Later, it was established that soluble peroxi-
dases, weakly associated to the cell wall, were most
sensitive to the phytopathogen . Since the formation
of ROS, including hydrogen peroxide, is now consid-
ered one of the basic mechanisms of the development
of plant immunity and systemic resistance, the changes
in soluble peroxidase activity can evidently indicate the
development of plant systemic resistance .
The objective of this work was to elucidate whether
peroxidase activity in potato leaves changed after root
infection with the virulent 5369 Cms strain. To this end,
it was necessary to study (1) peroxidase activity in var-
ious potato organs after root infection with the ring rot
agent and (2) the effects of EPS released by these bac-
teria on peroxidase activity.
MATERIALS AND METHODS
Two potato (
cultivars were used: cv. Lugovskoi (resistant to the
pathogen) and cv. Luk’yanovskii (susceptible to the
pathogen). Test-tube plantlets were grown from cut-
tings on agar-solidiﬁed MS supplemented with 10 g/l
sucrose (Reakhim, Russia), 1.0 mg/l thiamine, 0.5 mg/l
pyridoxine, 0.3 mg/l 8-hydroxyquinoline, 0.1 mg/l IAA
(Sigma, United States), 1.0 mg/l ascorbate, and
0.02 mg/l ferulic acid (Serva, Germany) . After ten
days, plants were transferred to the similar but liquid
medium and, after six more days, they were used for
co-culturing with the bacterial pathogen.
Suspension cultures were produced from calli
grown on leaf tissues of the same potato cultivars. To
this end, callus tissue (2–5 mg) was placed into 100 ml
of liquid MS supplemented with hormones and vita-
mins  and shaken until the suspension was produced.
We used the virulent 5369 strain
(Spieck. et Kotth.) Skapt et Burkh which was obtained
from the Research Institute of Potato Husbandry (Kore-
nevo, Moscow oblast). Bacteria were cultured on potato
agarized medium supplemented with 1.5% glucose for
5–6 days. Then cells were cultured at 25
C in a liquid
Changes in Peroxidase Activity during Potato Ring Rot Infection
I. A. Graskova, A. S. Romanenko, S. V. Vladimirova, and A. V. Kolesnichenko
Siberian Institute of Plant Physiology and Biochemistry, Siberian Division, Russian Academy of Sciences,
ul. Lermontova 132, Irkutsk, 664033 Russia;
fax: 7 (3952) 51-0754; e-mail: graskova@siﬁbr.irk.ru
Received August 21, 2002
—The effects of the ring rot causal agent
strain 5369) on the peroxidase activity of various tissues of potato plants grown under axenic conditions were
studied. Root infection enhanced peroxidase activity in all plant tissues (roots, leaves, and stems). In the resis-
tant cv. Lugovskoi, peroxidase activity was much higher than in the susceptible cv. Luk’yanovskii. Co-culturing
of the suspension cells of these potato cultivars with the bacterial pathogen also activated peroxidase in the cells
of the resistant cultivar; in the cells of the susceptible cultivar, peroxidase activation was less pronounced. Treat-
ing suspension cell with exopolysaccharides secreted by the pathogen enhanced the activity of extra- and intra-
cellular peroxidases, and the degree of this enhancement differed in the two potato cultivars.
Key words: Solanum tuberosum - Clavibacter michiganensis subsp. sepedonicus - pathogenesis - peroxidase
; EPC—exopolysaccharides; MS—Murashige and
Skoog nutrient medium; ROS—reactive oxygen species.