Phenolic compounds profiles of different barley varieties under the action of nanocomposite complex bacterial preparation Azogran in conditions of abiotic stress

Hordeum vulgare L. is a highly valuable cereal crop worldwide. However, its yield is decreasing due to increasing abiotic stresses. The prolonged action of oxidants creates an imbalance in the functioning of antioxidant systems. One important way to stabilize the redox homeostasis of plants is through the use of microbial preparations that enhance the synthesis of antioxidant compounds. At inoculation of seeds of the barley varieties (Burkhant, Virazh, and Copeland) with the nanocomposite complex bacterial preparation Azogran in plants, the levels of the most identified phenolic acids and flavonoids in the free and bound fractions were increased. Whereas in plants whose seeds were stressed with hydrogen peroxide (H₂O₂) and inoculated with Azogran, phenolic compounds (Ph-OH) with a high ability to inactivate the harmful effects of H₂O₂ dominated. In particular, in the plants of the Burkhant barley variety, the concentration-free chlorogenic (by 33.1%), syringic, benzoic, p-coumaric acids, rutin and bound chlorogenic, benzoic and trans-ferulic acids increased. In the plants of the Virazh barley variety, the levels of free caffeic, syringic acids, quercetin and bound 4-hydroxyphenylacetic (4-HPA), trans-ferulic, sinapic, trans-cinnamic acids, quercetin, and kaempferol increased. In plants of the Copeland barley variety, only the content of 4-HPA and trans-ferulic (by 79.9%) acids in the free fraction and syringic acid in the bound fraction was raised. Thus, despite the unequal response of different varieties of barley to the action of the bacterial preparation Azogran, the synthesis of those Ph-OH, which are an effective buffer against peroxide stress, increased in their plants.