BACTERIA BURKHOLDERIA VIETNAMENSIS WITH A COMPLEX OF PROPERTIES USEFUL FOR PLANTS REDUCE DROUGHT STRESS IN MOGAR (SETARIA ITALICA L.)

Foxtail millet ( Setaria italica L.) is a grain and fodder crop that is cultivated in the steppe regions of the Russian Federation, subject to periodic droughts. Since plants are closely related to the microorganisms living in their rhizosphere, the selection of beneficial bacteria and their use in crop production, including in adverse soil and climatic conditions, are considered a promising area of research. The purpose of this work was to study the role of a strain - a representative of the genus Burkholderia in stimulating plant growth and mitigating drought stress in Setaria italica . The bacterial strain B. vietnamiensis 8CH fixes atmospheric nitrogen, synthesizes indoleacetic acid (474.8 ng/ml) in rich nutrient media, mobilizes phosphates, and demonstrates antagonism against phytopathogenic fungi. At the same time, the effect of bacteria of the genus Burkholderia on the drought resistance of foxtail millet was studied for the first time. The taxonomic affiliation of the strain was clarified by determining the nucleotide sequence of the 16S RNA gene. Foxtail millet was grown in laboratory in pots under artificial lighting. Soil moisture was maintained at 60% of the total moisture capacity as standard and 20% to simulate drought. Protein was measured by Bradford, malondialdehyde - by reaction with thiobarbituric acid, peroxidase activity by the rate of oxidation of guaiacol. At 20% soil moisture, the treatment of foxtail millet with the B. vietnamiensis led to an increase of the shoots’ mass by 83%, and roots’ mass by 160%. The improvement of the foxtail millet plants’ status after the bacterial treatmenent was confirmed by a decrease in the concentration of the oxidative stress marker - malondialdehyde in the leaves to the control level. During study, at least two mechanisms of the anti-stress effect of bacteria in soil moisture deficiency were identified: activation of antioxidant enzymes and improvement of the water balance in plants. The activity of the peroxidase enzyme rose by 42%, and the relative water content in the leaves increased from 74 to 87%.