It is revealed that dipeptides glycylglycine (GlyGly) and glycylaspartic acid (GlyAsp), as well as the amino acid glycine (Gly), appreciably stimulated the growth and development of tobacco ( Nicotiana tabacum L.) regenerants and seedlings if they were present in a medium at 10 –7 М. All three compounds GlyGly, GlyAsp, and Gly influenced the cell differentiation and morphogenic processes in the calli. The compounds modulated expression of the KNOX and GRF family genes. The profiles of induction or repression of gene expression by one and the same peptide were found to differ in tobacco regenerants and seedlings. It is concluded that GlyGly, GlyAsp, and Gly may be considered as regulators of plant growth and development, the mode of action of which is signaling and mainly epigenetic.

Determining salt tolerance potential in wheat is one of the most important problems in breeding practice for areas with primary and secondary salinity. Presence of large areas of saline soils results in inhibition of growth, development and stability in obtaining high yields of agricultural plants. Therefore, there is a need for a comprehensive studying and improving of diagnostic methods during early growth stages. Different genotypes of wheat Triticum aestivum Host. and Triticum durum Desf. were used to identify salt tolerance markers. Both morphometric and some biochemical indicators of wheat varieties were used as salt tolerance markers. At this stage, it was shown that a comprehensive description of wheat varieties is needed to assess resistance of wheat varieties to chloride salinity.

The dipeptides glycylglycine (GlyGly) and glycylaspartic acid (GlyAsp) and amino acid glycine (Gly) in a concentration of 10 –7 M in a medium essentially stimulate the growth and development of tobacco ( Nicotiana tabacum ) calli. GlyGly, GlyAsp, and Gly influence the cell differentiation and tissue formation processes. They stimulate formation and growth of leaves and roots. After incubation of tobacco seedling roots in the presence of 10 –5 M fluorescent FITC-labeled peptides or glycine, marked fluorescence was observed in cells of the root cap and epidermis. The fluorescence was detected in the cell walls, cytoplasm, and nuclei. Thus, the peptides used can penetrate into the plant cell and be located in the nucleus and other cell compartments. Therefore, they may potentially interact with different structures and components of the cytoplasm and nucleus including various proteins, RNAs, and DNA. The penetration and accumulation of peptides in cells are tissue specific. In the tobacco callus, peptides modulate expression of the KNOX and GRF family genes that are responsible for cell differentiation and code for transcription factors. Thus, the dipeptides GlyGly and GlyAsp and amino acid Gly have marked physiological activity and can be related to efficient plant growth regulators.

Exogenous short biologically active peptides epitalon (Ala-Glu-Asp-Gly), bronchogen (Ala-Glu-Asp-Leu), and vilon (Lys-Glu) at concentrations 10–7-10–9 M significantly influence growth, development, and differentiation of tobacco (Nicotiana tabacum) callus cultures. Epitalon and bronchogen, in particular, both increase growth of calluses and stimulate formation and growth of leaves in plant regenerants. Because the regulatory activity of the short peptides appears at low peptide concentrations, their action to some extent is like that of the activity of phytohormones, and it seems to have signaling character and epigenetic nature. The investigated peptides modulate in tobacco cells the expression of genes including genes responsible for tissue formation and cell differentiation. These peptides differently modulate expression of CLE family genes coding for known endogenous regulatory peptides, the KNOX1 genes (transcription factor genes) and GRF (growth regulatory factor) genes coding for respective DNA-binding proteins such as topoisomerases, nucleases, and others. Thus, at the level of transcription, plants have a system of short peptide regulation of formation of long-known peptide regulators of growth and development. The peptides studied here may be related to a new generation of plant growth regulators. They can be used in the experimental botany, plant molecular biology, biotechnology, and practical agronomy.

Phytohormones, which are secreted peptides, play an important role in intercellular inter-actions, participating in the regulation of development and in numerous physiological processes and in responses to the influence of environmental factors. Short peptides in a concentration of 10-7-10-8 M regulate the growth and development of the callus culture of tobacco (Nicotiana tabacum L.) in culture in vitro. AlaGluAspGly, AlaAspGluLeu, GlyGly and GlyAsp on the 28th day of cultivation showed an increase in the biomass of tobacco by a factor of 1.5 to 2.5, an increase in the number of regenerants per explant by 10-30%, and also the area of the leaf plate of regenerants by 2-2.5 times. Exogenous peptides influence the expression of genes encoding the proteins of growth factor regulators. It was found that the expression values calculated by the PCR-PB method depend on the nature of the peptide. In addition, structurally different peptides differentially affect the different genes (growth regulating factor) of GRF. The greatest increase in the expression level of GRF family genes is observed in the presence of AlaAspGluLeu - GRF1, GRF3, GRF4 3.5-4 times, in the presence of AlaGluAspGly - GRF2 more than 4.5 times, GlyGly - GRF4 more than 3 times, GlyAsp - GRF3, GRF4 in 3-4 times. It is assumed that in the cell culture, short peptides can act as a regulator of the growth of new generation plants that can find application in biotechnology and practical plant growing.

In vitro reproduction is an important stage in seed potato propagation. Various radiation spectra can be used to regulate in vitro the growth and morphogenesis of potato seedlings (Solanum tuberosum L.). We studied the effect of light emitting diodes (LEDs) light sources, which differ in the spectral composition of the radiation, on the growth processes and functional parameters of the photosynthetic apparatus in potato plants (variety Agria) grown in vitro. The red LEDs with λm = 635 nm and the half-width of the emission band (HW) of 45 nm, blue LEDs with λm = 463 nm (HW = 23 nm), green LEDs with λm = 521 nm (HW = 38 nm), and white LEDs (400-730 nm) with an intensity of light equal to 60-65 micromol photons∕m-2∕s-1 at plant level, and white fluorescent lamps (OSRAM AG, Germany) of the same light intensity were used. On day 28 the growth parameters, CO2 gas exchange rate and parameters of variable chlorophyll fluorescence were measured. The highest biomass accumulation was observed during irradiation of plants with fluorescent lamps. A smaller plant biomass accumulation was observed when plants were irradiated with white LEDs. Blue LEDs was shown to reduce the accumulation of plant biomass by 49.5 % compared to the white LEDs. Irradiation with green and red LFDs led to decrease biomass accumulation by 75.6 and 67.5 %, respectively. The observed changes in the accumulation of dry plant biomass for different spectral ranges are associated with a higher activity of the photosynthetic apparatus of the plants grown under irradiation with blue and white LEDs. The rate of photosynthesis (per unit of the leaf surface) in these plants was higher than in those grown under green or red LEDs. The effective quantum yield of PS 2 in all studied plants had small changes in the range of 0.47 to 0.53, but higher values were observed in the plants grown under fluorescent lamps and white and green LEDs. Electron transport rate (ETR) and non-photochemical quenching (NPQ) were changed in similar manner under different growth conditions. Curve analysis showed that in the conditions when the input of CO2 was not limited the rate of photosynthesis decreased depending on lighters as follows: fluorescent lamps > white LEDs > red LEDs > blue LEDs > green LEDs. Maximal rate of carboxylation and greater efficiency of the reaction were observed when plants were exposed to fluorescent light and white LEDs. The irradiation of plants with blue, red and, especially, the green LEDs led to a decrease in carboxylation rate to 77.9, 67.9 and 11.1 % of the maximum values. Efficiency of carboxylation in plants grown under red and green LEDs sharply decreased to 37.5 % and 6.7 % of the maximum values. Electron transport rate when using fluorescent lamps, white, red, blue and green LEDs was equal to 100, 97.3, 75.1, 68.0 and 20.8 %, respectively. At the same time there has been a decrease in the utilization rate of triosophosphates to a value of 88.9, 48.7, 28.2 and 9.4 %, respectively, compared to 100 % under fluorescent lamps. Thus, at low levels of light intensity we did not observe significant changes in the activity of both light and dark photosynthetic reactions and the accumulation of plant dry matter. These results allow us to understand the role of separate regions of visible light on the functioning of the photosynthetic apparatus, and more effectively to use LEDs for plant cultivation.

Improving the efficiency of growing plants in phytotrons is largely linked to the introduction of advanced technologies, providing the optimization of the light conditions. The use of modern light sources such as light emitting diodes (LEDs) or induction lamps can reduce the energy consumption for growing plants due to the high light output, long work and control of the spectrum of irradiation. Comparative studies of growth processes and activity of the photosynthetic apparatus of plants of Basil ( Ocimum basilicum L.) variety Ararat, when using LEDs and induction lamps with an energy capacity of 64 and 150 W, respectively were done. The light intensity was 80-85 µmol photons•m -2•s -1 under LEDs white light and 240-260 µmol photons•m -2•s -1 under induction lamps. CO 2 gas exchange, the content of pigments and growth processes in plants grown in hydroponic conditions were estimated. The rate of photosynthesis under induction lamp was more than 2 times higher than under LEDs (2.6±0.4 and 1.2±0.3 µmol CO 2•m -2•s -1, respectively), although there was a slight decrease in the content of the chlorophylls (a + b) to 0.71±0.01 mg/g dry weigh compared to 0.83±0.03 for LEDs. More than twofold increase in the rate of photosynthesis did not result in the same increase in the accumulation of plant biomass that may be connected with different light saturation of growth processes and photosynthesis. The efficiency of biomass accumulation per 1 W of energy power for a period of 40 days under LEDs was 1.7 times higher than under the irradiation of induction lamp. Significant difference in photosynthetic efficiency was not detected. At elevated concentrations of CO 2 the rates of photosynthesis were comparable as a result of higher values of the quantum yield of photosynthesis, activity ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO) and the efficiency of carboxylation in LEDs plants. The investigation of structural and functional parameters of the photosynthetic apparatus and growth processes under the action of different light intensity showed the complex nature of the changes of some processes during long-term exposure to light of different intensity and spectral composition.

Improving the efficiency of growing plants in phytotrons is largely linked to the introduction of advanced technologies, providing the optimization of the light conditions.The use of modern light sources such as light emitting diodes (LEDs) or induction lamps can reduce the energy consumption for growing plants due to the high light output, long work and control of the spectrum of irradiation.Comparative studies of growth processes and activity of the photosynthetic apparatus of plants of Basil (Ocimum basilicum L.) variety Ararat, when using LEDs and induction lamps with an energy capacity of 64 and 150 W, respectively were done.The light intensity was 80-85 µmol photons•m -2 •s -1 under LEDs white light and 240-260 µmol photons•m -2 •s -1 under induction lamps.CO 2 gas exchange, the content of pigments and growth processes in plants grown in hydroponic conditions were estimated.The rate of photosynthesis under induction lamp was more than 2 times higher than under LEDs (2.6±0.4 and 1.2±0.3µmol CO 2 •m -2 •s -1 , respectively), although there was a slight decrease in the content of the chlorophylls (a + b) to 0.71±0.01mg/g dry weigh compared to 0.83±0.03for LEDs.More than twofold increase in the rate of photosynthesis did not result in the same increase in the accumulation of plant biomass that may be connected with different light saturation of growth processes and photosynthesis.The efficiency of biomass accumulation per 1 W of energy power for a period of 40 days under LEDs was 1.7 times higher than under the irradiation of induction lamp.Significant difference in photosynthetic efficiency was not detected.At elevated concentrations of CO 2 the rates of photosynthesis were comparable as a result of higher values of the quantum yield of photosynthesis, activity ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO) and the efficiency of carboxylation in LEDs plants.The investigation of structural and functional parameters of the photosynthetic apparatus and growth processes under the action of different light intensity showed the complex nature of the changes of some processes during long-term exposure to light of different intensity and spectral composition.

E (λ max 450±5 nm, 470±5 nm) light on growth processes and activity of photosynthetic apparatus in potato plants of the Nevskii early variety. It was made a conclusion, that application of light-emitting diode irradiators in controllable conditions of phytotron may be useful technique during potato growing subject to changes of spectrum composition in plant ontogenesis.

The authors investigated the effect of light-emitting diode irradiator with maximum in the region of red (λ max 6305 nm, 6605 nm) and blue (λ max 4505 nm, 4705 nm) light on growth processes and activity of photosynthetic apparatus in potato plants of the Nevskii early variety.It was made a conclusion, that application of light-emitting diode irradiators in controllable conditions of phytotron may be useful technique during potato growing subject to changes of spectrum composition in plant ontogenesis.