Effect of Endophytic Bacteria Bacillus subtilis on Seedling Growth and Root Lignification of Pisum sativum L. under Normal and Sodium Chloride Salt Conditions

The influence of endophytic bacteria Bacillus subtilis (strain 10-4) was studied on the parameters of growth and tolerance as well as the intensity of lignin deposition in the roots of Pisum sativum L. seedlings under conditions of sodium chloride salinity (1% NaCl). It was found that the impact of salinity reduced the germination energy, viability, length of the roots and shoots of seedlings, their wet and dry weight, and also increased the content of proline and the level of lipid peroxidation (LPO). Pretreatment with strain 10-4 had a stimulating effect on seedlings in normal conditions and a protective effect on salinity, which was reflected in the improvement of germination energy and seed viability, root length, and accumulation of their dry mass under saline conditions; however, in terms of shoot growth under stress, there was no significant difference from the control (nonbacterized) variants. At the same time, strain 10-4 promoted earlier formation of lateral roots as well as a decrease in stress-induced LPO and proline content in seedlings, which indicates that cells are protected from oxidative and osmotic damage under saline conditions. Priority data were obtained on the important role of endophytic B. subtilis strain 10-4 in the process of lignification and strengthening of the barrier properties of the cell walls of the roots, which contributes to the reduction of the toxic effect of sodium chloride salinity and the implementation of the protective effect of these bacteria on pea plants.