Vol 59, No 1 (2023)

The review is devoted to the analysis and systematization of modern data on the participation of endophytic plant growth-promoting (PGP) bacteria in the regulation of growth, development, yield formation, and stress resistance of cultivated plants, mainly spring wheat as the main bread crop. Presently known data on the interaction of plants with PGP-bacteria under normal and drought conditions are described. Particular attention is paid to the molecular mechanisms of regulation of plant metabolism by PGP-bacteria, as well as their role in reducing the negative effects of drought, achieved by modulating various processes in plants, for example, improving the supply of moisture and mineral nutrients, and activating the antioxidant and osmoprotective plant systems. A key role in the adaptation and resistance/tolerance of plants caused by PGP-bacteria are played by their ability to produce various metabolites with the properties of biologically active substances, including substances with antimicrobial and hormonal activity, enzymes and other compounds. Information about the endophytic microbiome of wheat is given, the elucidation of the role and functions of which in plant stress response and adaptation is necessary for the development of effective, safe strategies for their practical application in order to maximize the adaptation and productive potential of wheat under changing environmental conditions.

The basic strategy for the treatment of diabetes mellitus is the control of postprandial glucose levels, and therefore pancreatic α-amylase that hydrolyzes complex carbohydrates is an important enzymatic target for the scientific research. In the present study, an aqueous extract and its ethyl acetate fraction (EAF) from the seeds of Rhaponticum uniflorum had a pronounced inhibitory effect on the activity of human pancreatic α-amylase. Sixteen metabolites were isolated after the chromatographic separation of EAF and characterized as 4-O-, 5-O-, 3,4-di-O-, 3,5-di-O-, 4,5-di-O-caffeoylquinic acid, 6-hydroxyluteolin 7-O-glucoside, rhaunoside B, luteolin 7-O-(6"-O-caffeoyl)-glucoside, luteolin, carthamoside, carthamogenin, tracheloside, isoferuloyl-serotonin, 20-hydroxyecdysone, 2-deoxy-20-hydroxyecdysone and a new natural compound, which was carthamogenin 4-O-(6''-O-acetyl)-β-D-glucopyranoside (6''-O-acetyl-cartamoside). Quantitative HPLC data indicated a different distribution of the individual components between the endosperm and the seed coat. The study of the compounds effect on the activity of human pancreatic α-amylase showed that some flavonoids, caffeoylquinic acids, lignans and serotonin derivatives had a pronounced inhibitory effect. These results support the conclusion that Rhaponticum uniflorum seeds may be a useful natural source for the development of α-amylase inhibitory agents.

In the adhesion zone of the etiolated pea seedling roots, located at a distance of 5–15 mm from its apex, 1 and 24 hours after inoculation with the bacteria Rhizobium, the effect of exogenous 10^–11 M indol-acetic acid (IAA) and 10^–9 M 6-benzylaminopurine (BAP) on cell metabolism was investigated. The inoculated seedlings were used as control that is not exposed to the action of phytohormones. Phytohormone-induced changes in the activity of soluble and cell wall-related peroxidases (PO) and polyphenol oxidases (PPO), tissue concentrations of hydrogen peroxide (H₂O₂), nitric oxide (NO), “soluble” (extracted by ethyl acetate and n-butanol) and “insoluble” phenolic compounds (PCs), flavonoids are discussed. The analysis of the obtained results shows that in both observation periods, the exogenous effect of the IAA enhanced protective responses in the cells of the adhesion zone, and the action of BAP weakened them. It is shown that the differences in the metabolism of adhesion zone cells resulting from the action of exogenous BAP and IAA are related to their diametrically opposite effect on nodulation.

A sandwich bioassay for the quantitative determination of the recombinant beta-lactam receptor BlaR-CTD possessing ligand binding activity and immunoreactivity has been developed. In the bioassay system, BlaR-CTD present in a biological liquid or standard sample binds via its receptor site to ampicillin immobilized in a microplate well and interacts through the epitopes of its peripheral structure with specific polyclonal antibodies. The analytical sensitivity of the method proved to be 2 ng/mL, and its concentration range was 5–215 ng/mL. In the processes of heterological expression, isolation and reagent forms preparation, the biological activity of BlaR-CTD was monitored and its stability was evaluated. High purity recombinant beta-lactam receptor BlaR-CTD was obtained. The protein was shown to have a sufficiently high resistance to denaturation by chaotropic agents (urea and guanidine hydrochloride), and it was stable over a wide pH range. Also, we proposed the constructions and procedures of competitive bioassays for beta-lactam antibiotics using microplates (analytical sensitivity – 0.02 ng/mL, IC₅₀ = 0.28 ng/mL) or chromatographic test-strips (detection limit 1–2 ng/mL), which are based on the receptor and antigenic properties of BlaR-CTD.