The effect of growth regulators with antioxidant properties on the respiration process in potato plants under optimal and stress environmental conditions

Background. Respiration is the main energy process of the plant organism and a component of the production process, as a result of which it is of interest to study the ways of its regulation. Recently, researchers have been paying closer attention to synthetic and natural growth regulators with antioxidant functions: ambiol, Energia-M, and caffeic acid. At the same time, there are very few data on the effect of growth regulators with antioxidant functions on the parameters of the potato respiration process. In this regard, the aim of the study was to study the effect of ambiol, Energiya-M and caffeic acid on the respiration rate of the potato organs both under optimal conditions and under the action of hypothermia. Materials and methods. The object of the study is potato plants of the Vega and Zhukovsky early varieties. Variants of the experiment included treatment with synthetic regulators by soaking planting tubers in aqueous solutions of ambiol and Energia-M, as well as foliar treatment with a solution of caffeic acid. The effect of growth regulators on the respiration process was studied not only under optimal temperature conditions, but also under conditions of hypothermia simulating freezing. The intensity of respiration was determined by titration by the amount of released CO2. The rate of CO2 release after the plants were kept in the dark was used to judge the intensity of maintenance respiration. Growth respiration was calculated from the difference between the respiration of plants in the light and after keeping them in the dark. Respiratory pathways were studied using the method of specific inhibitors using NaF solution. Results. Ambiol and silicoauxin regulator increased respiration in Vega potato leaves at the stage of budding. The study of the process of respiration in tubers showed a somewhat different picture. Thus, the treatment with ambiol stimulated the process of respiration in tubers, while at the same time, in plants treated with the Energia-M regulator, the intensity of respiration in tubers decreased sharply against the control. Under laboratory conditions, ambiol and caffeic acid stimulated the respiration process. There were no significant differences in the effect of silicoauxin growth regulator on respiration rate from control. We also studied the effect of growth regulators on the quality of respiration. It was shown that, in contrast to the control variant, in which sodium fluoride blocked the respiration intensity of the leaves of the potato plant by more than 50 %, in the variant with ambiol, the respiration intensity was significantly less blocked. In the variants with the treatment of plants with Energia-M and caffeic acid, as well as in the control variant, sodium fluoride blocked the intensity of leaf respiration by 56 % and 60 %, respectively. Thus, when treated with these regulators, the process of respiration proceeded along the glycolytic pathway. It was also shown that the intensity of maintenance respiration increases under the action of all the studied antioxidants. The intensity of growth respiration when potato plants were treated with ambiol increased by 2 times compared to the control, and when treated with Energia-M, on the contrary, it decreased by 1.7 times. The treatment of plants with caffeic acid had no effect on the rate of respiration of the growth ofrenewal shoots. As our studies have shown, under optimal conditions, the treatment of potatoes with the growth regulator ambiol increased the intensity of respiration by 33 % compared with the control. Energia-M and caffeic acid had a lesser effect on increasing the intensity of breathing. 2 hours after exposure to hypothermia, the intensity of respiration decreased sharply in all experimental variants compared to the control. 24 hours after the stress, it was shown that against the background of treatment with ambiol and the Energia- M preparation, the respiration intensity in potato shoots increased significantly, while caffeic acid contributed only a slight intensification of this process. Conclusions. It was shown that the intensity of the respiration process and its components under optimal conditions and under the action of hypothermia were sensitive to the treatment of plants with growth regulators with antioxidant properties of both synthetic and natural origin. Under optimal conditions, the respiration process was stimulated, while under conditions of a 2-hour negative temperature, the studied regulators restrained its intensification. It was also shown that ambiol contributed to a greater extent to an increase in growth respiration, and Energiya-M - in maintenance respiration. The obtained experimental material also indicates the participation of the studied antioxidants in the regulation of the ratio of the components of the respiration process. In plants enriched with caffeic acid and treated with Energia-M, a predominantly glycolytic respiration pathway was noted

Polyanionic Carboxyethyl Peptide Nucleic Acids (ce-PNAs): Synthesis and DNA Binding.

New polyanionic modifications of polyamide nucleic acid mimics were obtained. Thymine decamers were synthesized from respective chiral α- and γ-monomers, and their enantiomeric purity was assessed. Here, we present the decamer synthesis, purification and characterization by MALDI-TOF mass spectrometry and an investigation of the hybridization properties of the decamers. We show that the modified γ-S-carboxyethyl-T10 PNA forms a stable triplex with polyadenine DNA

Schematic representation of PNA and DNA fragments.

<p>(A) DNA fragment; (B) <i>aeg</i>-, γ- and α-<i>ce</i>-PNAs; (C) Starting thymine monomers <b>4</b> and <b>5</b> and their conformers, which coexist in solution due to the reduced rotation along the N^<b>tert</b>-C(O)-bond.</p

Chromatographic profiles of the PNA monomer derivatives (diastereomers).

<p>(A) Mixture of diastereomers <b>7a</b> and <b>7b</b>; (B) Diastereomer <b>7a</b> (Conditions: Luna column, 5 μm, CN 100A, elution system: heptane/isopropanol (88/12), flow rate: 1 mL/min); (C) Mixture of diastereomers <b>8a</b> and <b>8b</b>; (D) Diastereomer <b>8a</b> (Conditions: Separon SGX RP-S C18 column, 5 μm, 4x150 mm, elution system: acetonitrile/water (1/1), flow rate: 1 mL/min); R = -CH₂CH₂COOBn.</p

UV-melting and CD spectra of PNA/DNA and DNA/DNA complexes.

<p>(A) Thermal difference spectra of the complexes; (B) Thermal denaturation profiles of the complexes; (C) CD spectra of the single-stranded oligonucleotides and PNAs. The molar ellipticity was calculated per 1 nucleotide. (D) CD spectra of the complexes. Conditions: 10 mM Na₂HPO₄ (pH 7.4), 140 mM KCl, 5 mM MgCl₂. The concentration of each PNA or oligonucleotide was 2.5 μM. The CD spectra were measured at 15°C.</p

J-Plots and CD spectra of γ-<i>ce</i>-H-(T₁₀)-Gly-NH₂ (2)/dA₁₀.

<p>(A) Absorbance of the γ-<i>ce</i>-H-(T₁₀)-Gly-OH (<b>2</b>)/dA₁₀ mixtures with various PNA/DNA ratios at 260 nm; (B) Absorbance of the mixtures at 275 nm; (C) Molar ellipticity at 263 nm. Conditions: 10 mM Na₂HPO₄ (pH 7.4), 140 mM KCl, 5 mM MgCl₂. The summed PNA and DNA concentration was 7 μM at each ratio; (D) CD spectra of the triplex. The molar ellipticity is given per 1 nucleotide in a strand. Conditions: 10 mM Na₂HPO₄ (pH 5 or 7.4), 140 mM KCl, 5 mM MgCl₂. The triplex concentration was 1.8 μM.</p

Chromatographic profiles of the PNA monomers (enantiomers).

<p>(A) Mixture of <b>4a</b> and <b>4b</b> (<i>S</i>- and <i>R</i>- enantiomers of the γ-monomer); (B) <i>S</i>-entantiomer of the γ-monomer, <b>4a</b> (Conditions: Diasphere column 110-Chirasel-E-PA, 7 μm; elution system: MeOH/CH₃COOH = 96/4 (v/v); flow rate: 1 mL/min; UV-detection at 254 nm; temperature: 20°C); (C) Mixture of <b>5a</b> and <b>5b</b> (<i>R</i>- and <i>S</i>-enantiomers of the α-monomer); (D) <i>S</i>-entantiomer of the α-monomer, <b>5a</b> (Conditions: Diasphere column 110-Chirasel-E-PA, 7 μm; elution system: MeOH/CH₃COOH/TEA = 100/0.1/0.1 (v/v/v); flow rate: 0.5 mL/min; UV-detection at 254 nm; temperature: 20°C); R = CH₂CH₂COOBn.</p