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The response of Triticum aestivum L. to infection by Septoria nodorum Berk, a pathogen causing speckled leaf blotch, was studied. The effect of salicylic acid (SA) and jasmonic acid (JA) signal molecules, as well as chitooligosaccharides (COSs) with different acetylation degrees (ADs), on the accumulation of hydrogen peroxide (Н2О2) in wheat leaves and the pathogenesis-related (PR) proteins of oxalate oxidase (AJ556991.1), peroxidase (TC 151917), and proteinase inhibitor (EU293132.1) was investigated. Treatment with the signal molecules inhibited S. nodorum growth and stimulated Н2О2 accumulation, as well as PR gene expression. SA and COS with 65% AD are found to be more efficient in Н2О2 induction and elevation of the transcriptional level of the oxalate oxidase and peroxidase genes. At the same time, JA and COS with 30% AD stimulated transcription of the proteinase inhibitor gene. The results suggest the existence of differential means of defense response induction by signal molecules with more prospects for the regulation of plant immunity.

The effect of infection with fungus Septoria nodorum strains differing in aggressiveness on the activity of hydrolytic enzymes (amylases and proteinases) and their protein inhibitors in the leaves of Triticum aestivum L. pretreated with salicylic and jasmonic acids was studied. It was shown that aggressive Septoria nodorum strains accelerated development, caused intensive necrotic reaction on the wheat leaves, increased the production of amylases and proteinases, and decreased the activity of their protein inhibitors. Salicylic and jasmonic acids altered the activity of the 'hydrolase-inhibitor' complex, which indicated the possibility of regulation of the activity (content) of this group of compounds via exogenous effects, including the treatment of plants with inducers of resistance of various natures. [ABSTRACT FROM AUTHOR]

The influence of salicylic (SA) and jasmonic (JA) acids as signaling systems mediators on the generation of HO and expression of genes encoding protective proteins was studied in the leaves of wheat Triticum aestivum L. upon infection with the pathogen of septoriosis Septoria nodorum Berk. It was found that presowing treatment of seeds with SA and JA decreased the development of the fungus on the leaves of wheat and had a stimulating effect on the production of H2O2 in the area of infection. An increased expression of genes encoding oxalate oxidase AJ556991.1 and anionic peroxidase TC 151917 was shown in infected tissues with the method of polymerase chain reaction. [ABSTRACT FROM AUTHOR]

Influence of mediators of the signal systems of salicylic (SA) and jasmonic (JA) acids and their mixture on reactive oxygen species' (ROS) (superoxide radical and O HO) generation and activity of oxidoreductases (oxalate oxidase, peroxidase and catalase) in leaves of wheat Triticum aestivum L. infected by Septoria leaf blotch pathogen Septoria nodorum Berk has been studied. Presowing treatment of seeds by SA and JA decreased the development rate of fungus on wheat leaves. SA provided earlier inductive effect on production of O and HO compared with JA. The protective effect of the salicylic and jasmonic acids against Septoria leaf blotch pathogen was caused by activation of oxalate oxidase, induction of anion and cation peroxidases, and decrease of catalase activity. Ability of compounds to stimulate ROS in the plant tissues can be used as criteria for evaluation of immune-modulating activity of new substances for protection of the plants. [ABSTRACT FROM AUTHOR]

The effect of salicylic acid (SA) on oxalate oxidase and peroxidase activities and hydrogen peroxide (H2O2) production in leaf cells has been studied in wheat of the susceptible cultivar Zhnitsa infected by Septoria nodorum, a pathogen of wheat leaf blotch. The results show that fungal hyphae spread into interstices between mesophyll cells and that infected tissues contain H2O2. Treatment with SA results in enhanced H2O2 production in mesophyll cells, which is due to activation of oxalate oxidase and peroxidase in the cell wall. It is proposed that the modulating effect of SA on oxidoreductase activities is involved in the induction of protective response to fungal infection in wheat plants. [ABSTRACT FROM AUTHOR]