The Relationship between the Antioxidant System and Proline Metabolism in the Leaves of Cucumber Plants Acclimated to Salt Stress

The study examines the effect of acclimation on the antioxidant system and proline metabolism in cucumber leaves subjected to 100 and 150 NaCl stress. The levels of protein carbonyl group, thiobarbituric acid reactive substances, α-tocopherol, and activity of ascorbate and glutathione peroxidases, catalase, glutathione S-transferase, pyrroline-5-carboxylate: synthetase and reductase as well as proline dehydrogenase were determined after 24 and 72 h periods of salt stress in the acclimated and non-acclimated plants. Although both groups of plants showed high α-tocopherol levels, in acclimated plants was observed higher constitutive concentration of these compounds as well as after salt treatment. Furthermore, the activity of enzymatic antioxidants grew in response to salt stress, mainly in the acclimated plants. In the acclimated plants, protein carbonyl group levels collapsed on a constitutive level and in response to salt stress. Although both groups of plants showed a decrease in proline dehydrogenase activity, they differed with regard to the range and time. Differences in response to salt stress between the acclimated and non-acclimated plants may suggest a relationship between increased tolerance in acclimated plants and raised activity of antioxidant enzymes, high-level of α-tocopherol as well, as decrease enzyme activity incorporates in proline catabolism.This research was funded by the Polish Ministry of Science and Higher Education. Grant number NN 302117735

The relationship between carbon and nitrogen metabolism in cucumber leaves acclimated to salt stress

The study examines the effect of acclimation on carbon and nitrogen metabolism in cucumber leaves subjected to moderate and severe NaCl stress. The levels of glucose, sucrose, NADH/NAD+-GDH, AspAT, AlaAT, NADP+-ICDH, G6PDH and 6GPDH activity were determined after 24 and 72 hour periods of salt stress in acclimated and non-acclimated plants. Although both groups of plants showed high Glc and Suc accumulation, they differed with regard to the range and time of accumulation. Acclimation to salinity decreased the activities of NADP+-ICDH and deaminating NAD+-GDH compared to controls; however, these enzymes, together with the other examined parameters, showed elevated values in the stressed plants. The acclimated plants showed higher G6PDH activity than the non-acclimated plants, whereas both groups demonstrated similar 6PGDH activity. The high activities of NADH-GDH, AlaAT and AspAT observed in the examined plants could be attributed to a high demand for glutamate. The observed changes may be required for the maintenance of correct TCA cycle activity, and acclimation appeared to positively influence these adaptive processes

Overexpression of phytochelatin synthase in tobacco: distinctive effects of AtPCS1 and CePCS genes on plant response to cadmium

Phytochelatins, heavy-metal-binding polypeptides, are synthesized by phytochelatin synthase (PCS) (EC 2.3.2.15). Previous studies on plants overexpressing PCS genes yielded contrasting phenotypes, ranging from enhanced cadmium tolerance and accumulation to cadmium hypersensitivity. This paper compares the effects of overexpression of AtPCS1 and CePCS in tobacco (Nicotiana tabacum var. Xanthi), and demonstrates how the introduction of single homologous genes affects to a different extent cellular metabolic pathways leading to the opposite of the desired effect. In contrast to WT and CePCS transformants, plants overexpressing AtPCS1 were Cd-hypersensitive although there was no substantial difference in cadmium accumulation between studied lines. Plants exposed to cadmium (5 and 25 μM CdCl2) differed, however, in the concentration of non-protein thiols (NPT). In addition, PCS activity in AtPCS1 transformants was around 5-fold higher than in CePCS and WT plants. AtPCS1 expressing plants displayed a dramatic accumulation of γ-glutamylcysteine and concomitant strong depletion of glutathione. By contrast, in CePCS transformants, a smaller reduction of the level of glutathione was noticed, and a less pronounced change in γ-glutamylcysteine concentration. There was only a moderate and temporary increase in phytochelatin levels due to AtPCS1 and CePCS expression. Marked changes in NPT composition due to AtPCS1 expression led to moderately decreased Cd-detoxification capacity reflected by lower SH:Cd ratios, and to higher oxidative stress (assessed by DAB staining), which possibly explains the increase in Cd-sensitivity. The results indicate that contrasting responses to cadmium of plants overexpressing PCS genes might result from species-dependent differences in the activity of phytochelatin synthase produced by the transgenes

Phenolic profiles in apple leaves and the efficacy of selected phenols against fire blight (Erwinia amylovora)

The content and type of phenolic compounds in apple leaves as potential markers of resistance to fire blight were analysed. The amounts of phenolic acids and flavonoids were determined before and after E. amylovora inoculation of leaves of two cultivars: ‘Enterprise’ (highly resistant) and ‘Idared’ (highly susceptible). The basic levels of phenolics in both cultivars was similar but, following the inoculation, in the resistant one faster and more distinguishable changes were observed. The difference between the cultivars was related to the content of the compounds and the rate of release of free phenols from their glucosides. Regarding age dependency, the levels of eight out of 15 phenolics was significantly higher in young leaves of ‘Idared” than in ‘Enterprise’. In the older leaves the differences were limited to four compounds. The amount of salicylic acid in ‘Idared’ was lower than in ‘Enterprise’. In ‘Idared’ accumulation of salicylate after infection was better pronounced than in ‘Enterprise’. Higher levels of naringenin glucosides, 4-hydroxbenzoic acid and gentisic acid were found in ‘Enterprise’. The activity of 13 phenolics tested in vitro against the pathogen showed that gallic acid, phloroglucinol, hydroquinone and phloretin, suppressed its growth. The aqueous solutions of gallic acid, phloroglucinol and hydroquinone also significantly limited the development of disease on pear fruitlet slices but only hydroquinone maintained its protective activity for longer time. It also showed very high efficacy in preventing disease spread on apple shoots. The study adds novel information on the contribution of specific phenolics to apple resistance to fire blight

Alleviation of nickel toxicity in wheat (Triticum aestivum L.) seedlings by selenium supplementation

Hydroponically grown wheat seedlings were treated with 50 μM N i and/or 15 μM Se. After a 7-day culture period, their growth parameters, N i, Se, F e, and M g contents, electrolyte leakage, photosynthetic pigment concentrations, and photochemical activity of photosystem II were determined. Exposure of wheat seedlings to N i alone resulted in reduction in the total shoot and root lengths, by 22% and 50%, respectively. Addition of Se to the N i-containing medium significantly improved the growth of these organs, compared to the seedlings subjected to N i alone. Application of Se decreased the accumulation of N i in shoots and roots and partially alleviated the N i-induced decrease in F e and M g concentations in shoots. Electrolyte leakage increased in response to N i stress, but in shoots it was diminished by Se supplementation. Exposure to N i led to a decrease in chlorophyll a and b contents and enhancement of chlorophyll a/b ratio, but did not influence the concentration of carotenoids. Enrichment of the N i-containing medium with Se significantly increased chlorophyll b content, compared to the seedlings treated with N i alone. Photochemical activity, estimated in terms of the maximum quantum yield of photosystem II, decreased in response to N i treatment but was significantly improved by simultaneous addition of Se. Results of our study suggest that alleviation of N i toxicity in wheat seedlings by Se supplementation may be related to limitation of N i uptake

Hippophae rhamnoides L. leaf and twig extracts as rich sources of nutrients and bioactive compounds with antioxidant activity

Plants have served for centuries as sources of compounds useful for human health such as antioxidant, anti-diabetic and antitumor agents. They are also rich in nutrients that improve the human diet. Growing demands for these compounds make it important to seek new sources for them. Hippophae rhamnoides L. is known as a plant with health-promoting properties. In this study we investigated the chemical composition and biological properties of bioactive components of ethanol extracts from leaves and twigs of H. rhamnoides L. Chemical components such as the total content of phenolic compounds, vitamins and amino acids and the antioxidant activities of these compounds in cellular and cell-free systems were assessed. The results suggest that the studied extracts are rich in bioactive compounds with potent antioxidant properties. Cytotoxicity and hemotoxicity assays showed that the extracts had low toxicity on human cells over the range of concentrations tested. Interaction with human serum albumin was investigated and conformational changes were observed. Our results indicate that leaf and twig extracts of H. rhamnoides L. should be considered as a non-toxic source of bioactive compounds which may be of interest to the food, pharmaceutical and cosmetic industries

Innovative approach for soil-structure interaction assessment

The severe damage caused by the Ms 8.1 Michoaćan earthquake in Mexico City in 1985 highlighted the potential effects of soil-structure interactions (SSI) during strong ground motion. Although SSI studies have been carried out for years, so far little attention has been paid to the analysis of the polarization of the wavefield radiated from a vibrating structure into its surroundings, which is necessary for a better characterization of the seismic wavefield. In the framework of this thesis, a novel approach for soil-structure interaction assessment based on waveform analysis is proposed. The approach is an innovative combination of deconvolution and polarization analysis of earthquakes recorded in a building and its surroundings. It allows the identification of the wave types of the radiated waves and the estimation of the energy of the radiated wavefield. The approach consists of four main steps: 1) evaluation of the dynamic behavior of the building, 2) deconvolution of the data recorded in the building and its surroundings, 3) identification of the seismic phase associated with the energy transmitted from the building to the ground and reconstruction of the radiated wavefield, and 4) polarization analysis. The proposed approach was tested using earthquake recordings from two experiments conducted in Italy. The first was carried out in 2019 in Matera, Italy, where a 7-story building and a nearby sports field were instrumented with three-component sensors. The second was conducted in 2022 at the test site in Piana di Toppo, Italy, where a single-degree-of-freedom (SDOF) structure was built to validate the approach in a simpler and more controlled environment. The frequency band containing most of the vibrational energy of the building in the Matera building was estimated using the spectral ratio method. Then, the earthquake data were deconvolved using a sensor at the top of the building as a reference. In order to identify the seismic phases of the complex deconvolved wavefield, a simple analytical transfer function was calculated based on a simplified geometry of the test site. In the analytical deconvolved wavefield, a peak related to the energy transmitted from the building to its surroundings was identified. The reconstructed radiated wavefield was significant compared to the signal recorded in the surroundings of the building and its energy was calculated to be up to 59~\% of the field signal. The polarization of the wavefield transmitted from the building to its surroundings was estimated as mostly linear in the analyzed frequency band. This could be explained, for example, by quasi-Rayleigh waves characterized by three planes in which radial and transverse components have a phase shift and the particle motion in the horizontal plane is elliptical. The built structure of the Piana di Toppo experiment did not transmit shaking energy back to the ground. This prevented the successful identification of the types of waves radiated and the amount of related energy amount. The results suggest that such an experimental design may not be suitable for an SSI experiment. The wavefield radiated from the building in Matera consisted of unconventionally polarized surface waves. Moreover, the energy radiated back from the building showed that the influence of the building on the ground motion was significant for the horizontal components in the considered frequency band. However, for the second experiment, no wavefield radiated from the built structure could be identified, and the results obtained in this thesis are limited to the recordings of only one earthquake. Therefore, more data need to be analyzed to confirm these observations. Further analysis with different data sets will be performed in the future to validate the proposed approach and the obtained results.The severe damage caused by the Ms 8.1 Michoaćan earthquake in Mexico City in 1985 highlighted the potential effects of soil-structure interactions (SSI) during strong ground motion. Although SSI studies have been carried out for years, so far little attention has been paid to the analysis of the polarization of the wavefield radiated from a vibrating structure into its surroundings, which is necessary for a better characterization of the seismic wavefield. In the framework of this thesis, a novel approach for soil-structure interaction assessment based on waveform analysis is proposed. The approach is an innovative combination of deconvolution and polarization analysis of earthquakes recorded in a building and its surroundings. It allows the identification of the wave types of the radiated waves and the estimation of the energy of the radiated wavefield. The approach consists of four main steps: 1) evaluation of the dynamic behavior of the building, 2) deconvolution of the data recorded in the building and its surroundings, 3) identification of the seismic phase associated with the energy transmitted from the building to the ground and reconstruction of the radiated wavefield, and 4) polarization analysis. The proposed approach was tested using earthquake recordings from two experiments conducted in Italy. The first was carried out in 2019 in Matera, Italy, where a 7-story building and a nearby sports field were instrumented with three-component sensors. The second was conducted in 2022 at the test site in Piana di Toppo, Italy, where a single-degree-of-freedom (SDOF) structure was built to validate the approach in a simpler and more controlled environment. The frequency band containing most of the vibrational energy of the building in the Matera building was estimated using the spectral ratio method. Then, the earthquake data were deconvolved using a sensor at the top of the building as a reference. In order to identify the seismic phases of the complex deconvolved wavefield, a simple analytical transfer function was calculated based on a simplified geometry of the test site. In the analytical deconvolved wavefield, a peak related to the energy transmitted from the building to its surroundings was identified. The reconstructed radiated wavefield was significant compared to the signal recorded in the surroundings of the building and its energy was calculated to be up to 59~\% of the field signal. The polarization of the wavefield transmitted from the building to its surroundings was estimated as mostly linear in the analyzed frequency band. This could be explained, for example, by quasi-Rayleigh waves characterized by three planes in which radial and transverse components have a phase shift and the particle motion in the horizontal plane is elliptical. The built structure of the Piana di Toppo experiment did not transmit shaking energy back to the ground. This prevented the successful identification of the types of waves radiated and the amount of related energy amount. The results suggest that such an experimental design may not be suitable for an SSI experiment. The wavefield radiated from the building in Matera consisted of unconventionally polarized surface waves. Moreover, the energy radiated back from the building showed that the influence of the building on the ground motion was significant for the horizontal components in the considered frequency band. However, for the second experiment, no wavefield radiated from the built structure could be identified, and the results obtained in this thesis are limited to the recordings of only one earthquake. Therefore, more data need to be analyzed to confirm these observations. Further analysis with different data sets will be performed in the future to validate the proposed approach and the obtained results

The Role of Knowledge in the Processes of Creating and Implementing Innovations

The dynamics of changes in the environment of the organizations stimulates them to design and implement internal changes leading to a balance between organizations and their environment. These changes refer to the formulation of the main objectives of the organization, structural and process solutions, management concepts, relations with customers, another look at the resources, the use of knowledge as a source of innovations etc