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128 L.A. Shcherbakovapathogen-controlling compounds within the statin group and their derivatives.Such screening might lead to the detection of new natural polyketideswith high protective activity that would not have an adverse effect on plants.Since the agricultural application of statin-based formulations does notdemand as high a level of statin purification as that in the pharmacologicalindustry, using a relatively simple isolation procedure (Dzhavakhiya, 2008)and the ‘superproducer’ strains suggests that statin-based plant- protectiontechnology would be a more economical and ecologically safe strategy thanany method using chemical pesticides.5.4 ConclusionThe disease-preventing effect of natural compounds is a result of a direct orplant-mediated influence on targeted pathogens. The compounds can affectphytopathogens directly, interrupting pivotal metabolic pathways andresults in the death of the pathogens (biocidal effect). Some natural substancesor their analogues specifically influence pathways related to pathogenicityand toxigenesis. In the case of a plant-mediated mode of action,natural compounds elicit and activate defence responses in plants that resultin induced resistance to diseases. In addition, some biogenic compoundsinfluencing plants do not induce resistance but enhance tolerance to pathogensby improving the physiological state of plants. The structural and functionaldiversity of natural compounds as well as their abundance provide agreat potential for bringing plant-protection technologies in line with greenconsumerization.ReferencesAhrenholtz, I., Harms, K., De Vries, J. andWackernagel, W. (2000) Increased killingof Bacillus subtilis on the hair rootsof transgenic T4 lysozyme-producingpotatoes. Applied and EnvironmentalMicrobiology 66, 1862–1865.Asaka, O. and Shoda, M. (1996) Biocontrol ofRhizoctonia solani damping-off of tomatowith Bacillus subtilis RB14. Applied andEnvironmental Microbiology 62, 4081–4085.Bais, H.P., Fall, R. and Vivanco, J.M. (2004)Biocontrol of Bacillus subtilis againstinfection of Arabidopsis roots byPseudomonas syringae is facilitated by biofilmformation and surfactin production.Plant Physiology, 143, 1–13.Bassarello, C., Lazzaroni, S., Bifulco, G., LoCantore, P., Iacobellis, N.S., Riccio, R.,Gomez-Paloma, L. and Evidente, A. (2004)Tolaasins A–E, five new lipodepsipeptidesproduced by Pseudomonastolaasii. Journal of Natural Products 67,811–816.Benitez, T., Limon, C., Delgado-Jarana, J. andRey, M. (1998) Glucanolytic and otherenzymes and their genes. In: Harman,G.E., Kubicek, C.P. (eds) Trichoderma andGliocladium: Enzymes, biological controland commercial application, Taylor &Francis, London, 2, 101–128.Bolar, J.P., Norelli, J.L., Wong, K-W., Hayes,C.K., Harman, G.E. and Aldwinckle, H.S.(2000) Expression of endochitinase fromTrichoderma harzianum in transgenic appleincreases resistance to apple scab andreduces vigor. Phytopathology 90, 72–77.