Phenylalanine Ammonia-Lyase Enzyme Activity in the Symbiotic System Glycine max – Bradyrhizobium japonicum by Seed Inoculation Different in Activity and Virulation Strain and Treatment with Fungicides

Abstract

Phenylalanine ammonia-lyase (PAL) is a key enzyme of the phenylpropanoid pathway and provides precursors for the synthesis of many secondary metabolites, which are necessary for the development and protection of plants from external factors of various natures, in particular plays an important role in the formation and development of their symbiosis with microorganisms. Aim. To study the activity of PAL in soybean plants in the early stages of legume-rhizobial symbiosis under the influence of seed inoculation with Bradyrhizobium japonicum strains with different symbiotic properties on the background of fungicide treatment. Methods. Microbiology (bacterial culture growing, seeds inoculation), physiological (pot experiment), biochemical (determining the PAL enzyme activity). Results. Inoculation of soybean seeds with active virulent rhizobia induces a significant decrease in PAL activity in the roots at the primordial leaf stage and a significant increase in its activity level at the first true leaf stage, compared to inactive symbiosis. At the stage of third true leaf, the activity of PAL increased more significantly in soybean root nodules formed by inactive rhizobia, compared to active symbiosis. However, at the stage of third true leaves, the activity of PAL in soybean root nodules formed by inactive rhizobia increased significantly compared to active symbiosis. The use of fungicides for pre-sowing treatment of soybean seeds induces changes in the level of PAL activity in roots and nodules, which do not affect the overall dynamics of enzyme activity in different effective symbiotic systems Glycine max - Bradyrhizobium japonicum. Conclusions. The activity of PAL in the roots and especially in the root nodules of soybeans in the early stage of plant development in the case of fungicides using and bacterization is primarily due to the action of the inoculation factor, and is determined by the symbiotic properties of rhizobia strains, in particular, their virulence and nitrogen fixation activity.