Influence of endophytic and epiphytic nitrogen-fixing bacteria on the content of negative allelopathic compounds in root exudates of pea (Pisum sativum L.) seedlings

Abstract

Substances that have a harmful effect on living organisms include N-phenyl-2-naphthalamine and phthalates, which are synthesized and widely used in the chemical industry. At the same time, N-phenyl-2-naphthylamine was found in the aerial parts and in the roots of some plant species, phthalates were found in many plant species and in bacteria. The aim of this research was to study the protective (antimicrobial) reaction of pea (Pisum sativum L.) seedlings of the Torsdag variety to the inoculation with bacteria Rhizobium leguminosarum bv. viceae (endosymbiont) and Azotobacter chroococcum (ectosymbiont) introduced into the aqueous medium of root growth were studied. Changes in the content of negative allelopathic compounds (pisatin, N-phenyl-2-naphthylamine, phthalates) in root exudates were the reaction indicators. After the inoculation, the seedlings grew for 24 h in the BINDER KBW-240 chamber at 21 °C, with lighting of 81 μM.m-2 . sec-1 and a 16/8 h day/night photoperiod. In ethyl acetate extracts from the aqueous medium where the seedling roots were immersed, the content of the compounds was determined by HPLC, while changes in the composition and ratio of phthalates were determined by GC-MS. Data indicating the different ability of both bacterial species to degrade N-phenyl-2-naphthylamine to phthalates and the dependence of this process activity in the bacteria studied on its concentration in the medium were presented. N-phenyl-2-naphthylamine differently but negatively affected the viability and growth of the bacteria used in the experiments. A different effect of rhizobia and azotobacter on the content of the above named compounds and on the ratio of types of phthalates in root exudates was elicited.