The Interplay Between Salicylic and Jasmonic Acid During Phytopathogenesis - Salicylic Acid: Plant Growth and Development - page 275

content the mitochondrial alternative oxidase participates (Chaturvedi and Shan
2007 ). Besides, it is also considered that the accumulation of H 2 O 2 under the
influence of SA is due to catalase inhibition (Chen et al. 1993 ) and SA binding
activity to the heme group of ascorbate peroxidase (Vlot et al. 2009 ). Therefore,
the relationship between H 2 O 2 and SA isn't so simple, because H 2 O 2 and SA are
substrates for peroxidases and participate in signalling regulation of gene
expression which have directs antibiotical effect on pathogens (Kawano and
Furuichi 2007 ). The consequence of inhibitory activity of SA on reactive oxygen
species scavengers in plants would be the elevated level of H 2 O 2 in the immediate
vicinity of the infection site and this level has been postulated to act as a second
messenger of SA in the signal-transduction pathway leading to SAR and activation
of genes encoding PR proteins (An and Mou 2011 ; Liu et al. 2010 ).
One of the evidences of the peroxidase regulation during pathogenesis is the
inhibition of the oxidative burst induced by SA in plants treated by peroxidase
inhibitors—salicylhydroxamic acid or monodehydroascorbate (Kawano and Muto
2000 ). Proteomic analysis of Pisum sativum apical meristem showed that ascorbate
peroxidase neutralizing H 2 O 2 in ascorbate-glutathione cycle was induced by SA.
However, apoptosis-inducing concentration of SA (100 lM) reduced the content
of this enzyme (Tarchevsky et al. 2010 ). Apparently, for triggering of SA-induced
genes the oxidative burst caused by pathogen penetration is necessary. So, in SA-
treated asparagus plants, infected by root rot pathogen the increase of peroxidase
activity was found, but individual influence of SA or pathogen did not lead to this
observation (He and Wolyn 2005 ).
A variety of class III peroxidase genes are SA-induced, although the majority of
them are not SA-competent, in the strict sense. It is expected that sensibility to SA
is a specific ''marker'' of peroxidases, participating in the defence reactions
(Almagro et al. 2009 ). So, in our investigations in wheat plants under the influence
of SA the activity of peroxidase with pI * 3.5 and pI * 9.7 in cytoplasmic
fractions of proteins increased. Interestingly, these isoperoxidases can interact with
some surface structures of pathogenic fungi, example, chitin and glucans
(Maksimov et al. 2010 ). Recently we found that SA promoted transcription of
genes encoding anionic peroxidase in wheat, infected by pathogenic fungus Sep-
toria nodorum (Burchanova et al. 2007 ). The treatment of parsley calli by syn-
thetic analogue of SA (benzothiodiasole) induced the expression of anionic
isoperoxidase (Katz et al. 1998 ).
It should be noted that SA can stimulate the capacity of peroxidases to produce
O 2 - and inhibit the antioxidant activity of that simultaneously (Kawano and
Furuichi 2007 ; Almagro et al. 2009 ). It causes the SA-radicals generation and
production of some phenolic compounds participating in antibiotics synthesis
(phytoalexines, terpenes, alcaloides) (Okazaki et al. 2004 ; Reszka et al. 2005 ) and
lignin polymerization. SA-radical (or SA) can take part in lipid peroxidation
(Kawano and Furuichi 2007 ; Hatamzadeh et al. 2012 ) and SA-induced expression
of PR1 gene was suppressed by diethyldithiocarbamate converting peroxy-

derivatives of fatty acids in hydroxylic forms (Kawano et al. 2003 ).