Abstract : The purpose of this study was to reveal by optical microscopy and ultra-microscopy the changes induced in the cells and tissues of strawberry plants by different treatments with elicitors obtained from fungal strains to activate various metabolic pathways involved in the defense response of plants against pathogens. The diseases control is generally based on use of chemical pesticides, genetic resistant plant species and adequate agro-technical measures. Environment pollution with pesticide residues and the long period necessary to obtain genetic resistance in crop plants led to finding strategies based on inducing plant defense mechanism by appropriate stimuli. Thus, research has demonstrated the possibility to induce plant resistance to various pathogens from genera Fusarium, Plasmopara, Verticillium, Erwinia, Pseudomonas. Attempts have been done to assess the morphological and biochemical basis of resistance in plants of tomato, sun-flower, grapes or cotton. In vitro and in vivo experiments have been carried out in order to study and reveal the modifications in strawberry leaf blade tissues and cells ultra-structure during the defense response to pathogen Botrytis cinerea induced by E1, E2 and E3 preparations of microbial origin. Leaves sampled from strawberry plants cv. Senga Sengana have been examined by optical and electron microscopy. Immunodiffusion tests have been carried out from plant extracts with biochemical chemical composition. The comparative effect of pathogen control measures was assessed by monitoring plant health paramenters. The phenomenon of induced plant resistance was approached by new and modern  interdisciplinary methods, including connections between plant histology, pathology and immunology. In vitro and in vivo experiments brought evidence that practical use of fungal preparations as signals to induce plant resistance to pathogen Botrytis cinerea, has a scientific base, improving defense mechanisms. The paper present images and results of measurements carried out in leaf blade tissues and evidences of thickening of mesophyllum and epidermis. Intracellular accumulations of phenols were evidenced proving the activation of defense mechanisms. The paper presents original data and photographs in a new scientific field represented by plant immunology and use of natural mechanisms for increasing strawberry resistance to pathogen Botrytis cinerea. Research was supported by PNCDI II Research Program, Projects nos. 31-078/2007 and 52-112/2008.

plant resistance; fungal extract; strawberry; Botrytis cinerea; leaves morphology

Presentation: oral