ISSN 10214437, Russian Journal of Plant Physiology, 2015, Vol. 62, No. 5, pp. 586–594. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © A.A. Aver’yanov, T.D. Pasechnik, V.P. Lapikova, T.S. Romanova, C.J. Baker, 2015, published in Fiziologiya Rastenii, 2015, Vol. 62, No. 5, pp. 628–637.
Systemic acquired resistance (SAR) to diseases
emerges in susceptible plants in response to certain
influences of so called inducers. SAR spreads through
out the plant and exhibits resistance against subse
quent challenge infection on distant zones . Local
death of plant cells caused by physical factors ,
intoxication [3, 4], or hypersensitive response to infec
tion with avirulent pathogens  is a frequent cause of
SAR. Another cause is a local overproduction of ROS
(“oxidative burst”), which is associated, although not
necessarily, with cell death .
Oxidative burst systemically protecting from dis
eases may be evoked by different ways, for example, by
introduction of external ROS or ROS sources. For
The article was translated by the authors.
instance, such action was reported for exogenous
hydrogen peroxide . Herbicide Paraquat reduces
dioxygen to superoxide at the expense of electron
transfer chains, and riboflavin does this due to photoox
idation of methionine . Respectively, the two com
pounds protect systemically cucumber from anthra
cnose  and rice from blast . Similar control of
tobacco viral mosaic  and scab of cucumber  is
afforded by photodynamic dyes yielding singlet oxygen
under light. Many substances, in particular elicitors,
stimulate endogenous ROS sources leading finally to
systemic resistance .
ROS level rises not only because of increased for
mation but also decreased decay. The latter occurs
upon inhibition of antioxidant systems, in particular,
enzymatic. For example, inhibition of plant catalase
leading to accumulation of hydrogen peroxide is rec
ognized as one mechanism of antiinfective action of
salicylic acid. Similar mechanism is supposed for
isonicotinic acid and benzothiadiazole . It is con
ceivable that other inhibitors of antioxidant enzymes
Systemic Reduction of Rice Blast by Inhibitors
of Antioxidant Enzymes
A. A. Aver’yanov
, T. D. Pasechnik
, V. P. Lapikova
, T. S. Romanova
, and C. J. Baker
AllRussian Research Institute of Phytopathology,
Bolshie Vyazemy, Moscow region, 143050 Russia
Molecular Plant Pathology Laboratory, Agricultural Research Service USDA, Beltsville, Maryland, 20705 United States
Received February 25, 2015
—Systemic acquired disease resistance (SAR) of plants may result from an oxidative burst in their tis
sues caused by both increased production of ROS and decreased antioxidant activity, in particular, enzymatic.
Here we tested whether the exogenous inhibitors of superoxide dismutase (SOD) and catalase (CAT), respec
tively, diethyldithiocarbamate (DDC) and aminotriazole (AT), can systemically protect rice (
from blast disease caused by fungus
Conouch et Kohn. The possible involvement of ROS
in the protection was also examined. It was found that DDC did not affect fungal spore germination, and AT
partially retarded it. Both compounds were nontoxic to plants and, when applied to the 4th leaf, greatly reduced
the disease symptoms on the challenged 5th leaf. The protective action of AT apparently depended on the pres
ence of hydrogen peroxide since the protection was diminished by a scavenger of H
applied to the same leaf after AT, while exogenous H
, applied in place of AT, controlled the disease. Endog
enous peroxide might accumulate due to inhibition of CAT that was actually observed in ATtreated leaves.
Treatments of the 4th leaf with DDC or AT stimulated superoxide formation in the diffusate of the infected
5th leaf (as against treatment with water) pointing to the possible involvement of ROS in systemic defense
responses. The same diffusates had enhanced fungitoxicities, which were reduced when antioxidants were added
to the diffusate. Therefore, inhibitors of antioxidant enzymes systemically reduced rice blast, possibly via SAR.
Both mechanisms of SAR induction (in the treated leaf) and expression (in the systemically protected leaf)
might be mediated by ROS.
Keywords: Oryza sativa, Magnaporthe oryzae
, aminotriazole, catalase, diethyldithiocarbamate, reactive oxy
gen species, rice blast, superoxide dismutase, systemic acquired resistance
: AT—aminotriazole; DDC—diethyldithiocarbam
ate; CAT—catalase; DMTU—dimethylthiourea; —super
oxide radical; SAR—systemic acquired resistance; SOD—super