Valutazione degli effetti di tecnologie elettrochimiche avanzate nella lotta contro patologia del Pomodoro, in laboratorio ed in serra

A plant pathogen is an organism that, in order to complete some or all of its life cycle, grows inside the plant and, in doing so, causes harmful effects on the host plant. Since the plants are continuously threatened by the attack of pathogens, and given their condition of immobility (which precludes any possibility of escape), each cell is structured in such a way as to be able to defend itself. The plants possess pre-existing defenses (always present), already pre-constituted, made of physical barriers and toxic compounds or secondary metabolites with antimicrobial properties. They also have inducible defenses, which confer resistance against most pathogens. In fact, through evolution, plants have selected one or more resistance genes (called "R-genes") that protect them from infection. The well-known problems associated with the use of pesticides have prompted the search for new substances, possibly more "friendly" (in the sense of being effective and less harmful to the environment). In recent years it has been established that the electrochemically activated water (EAW) has a strong bactericidal and fungicidal activity against many pathogens, and this is primarily due to the presence of hypochlorous acid (the predominant form of active chlorine at neutral pH). The biocidal properties of the EAW, such as sodium hypochlorite, have aroused interest in the use of such substances in agriculture, especially in post-harvest but recently also in the pre-harvest. The experiments, performed on tomato plants, have shown that one can obtain appreciable results in the field due to the application of EAW, as well as solutions of sodium hypochlorite having appropriate pH and concentration of free chlorine. In particular, there are significant differences both in the height reached by the treated plants, compared to the so-called "mock" (untreated plants), and in the increase of production (expressed as pounds of product per plant). One of the main pathogen of tomato is represented by the fungus Oidium (Leveillula turica). Experiments performed using EAW, showed a greater resistance to the pathogen in the treated plants. Since the tomato plants treated with EAW seem to show a better fitness, it is plausible that the biocide present in EAW (hypochlorous acid) acts directly on the plants, not only on pathogens. The objective of this research is to investigate the positive effect of EAW on plants at the cellular and molecular level. For this purpose, the study was conducted both on tobacco, well known at the physiological and at molecular-genetic level, and on tomato plants. Both plant species appear easily manageable in controlled environment (growth chambers) and in the laboratory. The research was carried out by determining the gene expression profiles obtained after treating the plants with EAW or with sodium hypochlorite solutions. The results obtained on tomato show how a first treatment with EAW is able to rapidly increase the amount of mRNA of pathogen-related genes such as PR-1a, PR-1b (protease), as well as those relating to the WRKY genes. The magnitude of the effect obtained suggests that the EAW not only acts as a biocide against pathogens present on the leaf surfaces of the plant, but is also capable of triggering endogenous defenses in the plants via an increase in the production of defensive proteins thus further enhancing the defenses. The resulting increased general well-being is reflected in a greater growth and in a significant improvement in the quality of production.