Phthalates (esters of o-phthalic acid) are best known as products of the chemical industry. For a long time, they were considered purely xenobiotics and pollutants. To date, however, a lot of information has appeared on the presence of biogenic phthalates in organisms of various phyla. Direct evidence of phthalate biosynthesis from labelled precursors has been obtained. Phthalates have been detected in plants taken from natural habitats as well as in closed experimental systems with controlled growth conditions – in plants and cell cultures grown in vitro. It should be noted that in situ plants were of different phyla, different ecological specializations and grew in different regions of Russia (Crimea, Siberia). In some studies, the antimicrobial activity of phthalates against gram-positive and gram-negative human pathogens has been found; their cytotoxic properties have been detected. Moreover, the ability of cells to excrete phthalates into the extracellular environment under stress has been disclosed. That may have biological significance in the interaction of various organisms. Fairly recently, experimental data on the participation of phthalates in suppressing the growth of phytopathogenic microorganisms have become available. The facts suggest that plants use these substances as protective compounds. Biofilm formation is known to determine the display of virulence of pathogens increasing their hardiness to plant resistance factors and blocking the xylem flux. It should be noted that the effect of phthalates on phytopathogenic bacteria was practically not studied earlier. According to our data, adding dibutyl phthalate to the culture medium of bacteria reduced the intensity of biofilm formation both in the biotroph Clavibacter michiganensis ssp. sepedonicus and in the necrotroph Pectobacterium carotovorum ssp. carotovorum. It is important to note the fact that in such a case there was an increase in the growth of bacterial cultures. The effect was similar when using di-2-ethylhexyl phthalate. On the data obtained, it can be assumed that phthalates are involved in the protection of plants from infections suppressing the process of biofilm formation of bacterial phytopathogens – the initial stage of plant colonization. Meanwhile, phthalates have been found in the cells of phytopathogenic bacteria. When growing Clavibacter michiganensis ssp. sepedonicus in Petri dishes in minimal medium with a dibutyl phthalate gradient of 0-60 μg/l, growth of bacteria was observed towards the gradient concentration increase. That indicates the physiological reaction of bacteria to the presence of phthalates. Rather ambiguous results suggest that the physiological and biochemical role of phthalates can be much more complex and not be limited to the participation of plant organisms in the protective process.
|Position of speaker||senior reseacher|
|Affiliation of speaker||Siberian Institute of Plant Physiology and Biochemistry SB RAS, Irkutsk, Russia, VendyS@yandex.ru|
|Publication||International journal «Resource-Efficient Technologies»|