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Flavonoid aglycone profiles of cultivated plants of Achillea collina, A. asplenifolia and cultivar "Proa" presented with different origins were compared. The evaluation was undertaken to determine intraspecific variability of flavonoid profiles when the plants are grown in the uniform conditions. Eight flavonoid aglycones were detected by thin layer chromatography and comparison with known compounds. Highly methylated quercetagetin derivatives predominate in the exudates. The flavonoid profiles of A. colina consist mainly of quercetagetin 3,6,4'-trimethyl ether (centaureidin), 6-hydroxykaempferol 3,6,4'-trimethyl ether and quercetagetin 3,6,7,4'-tetramethyl ether (casticin) while the profiles of A. asplenifolia of quercetagetin 3,6,7,3',4'-pentamethyl ether (artemetin), casticin and scutellarein 6,4'-dimethyl ether. In the profiles of A. asplenifolia quercetagetin 3,6,4'-trimethyl ether was not found in the extracts of one of the two origins. The extracts of cultivar exhibited a less diversified flavonoid profile with main component centaureidin. No significant difference was found in the flavonoid profiles of the extracts of the both origins of the cultivar “Proa” and A. collina.

The medicinal plants of Achillea millefolium group are largely collected from their natural habitats this leading to both ecological risks and heterogeneity of the collected market samples. Our previous studies supplied evidence that field cultivation of wild species of the group (A. collina and A. asplenifolia) is a promising approach to obtain homogenous plant material without damage to the environment. In these studies inflorescences were the object of field experiments while in the present paper stems and leaves were investigated. The experimental design involved the above mentioned species (each with two populations) the seeds being collected from the natural habitats of plants. Cv. Proa bred for field cultivation was used as a standard; its seeds were purchased from the firm "Pharmasaat GmbH", Germany. The results confirm the findings of our previous work carried out with inflorescences, namely that stems and leaves contain flavonoids above the reference limit of European Pharmacopoeia (3 mg/g). This accounts for the high AO and AR activities as shown by the strong correlation between flavonoids and these items. Moreover, similarly to inflorescences, stems and leaves show low intraspecific variability and larger interspecific differences with regards to all characters studied. This suggests to the species studied being isolated and distant enough to serve as a homogenous source of raw yarrow material for the market. A. asplenifolia is distinguished by a higher potential of valuable components than A. collina while being closer by all parameters to cv. Proa. These data point to A. asplenifolia as a promising species for field cultivation. The weight ratio of plant parts shows that inflorescences dominate followed by stems and leaves. [ABSTRACT FROM AUTHOR]

Sunflower plants (Helianthus annuus L.) cv. 1114 were used as test plants to investigate the combined toxicity effect of heavy metals present in soils collected from three different locations of a polluted area near a non-ferrous metal smelter. Soils were designated as highly contaminated, moderately contaminated and non-contaminated (control) based on the content analysis of soil samples. The photosynthetic performance was assessed by the changes in the functional activity of PS1 (photosystem 1) and PS2 (photosystem 2). Evidence for accelerated electron flow beyond the first qiunone acceptors in PS2 (QA) but not related with accelerated reduction of the first acceptor of light in PS1 (P700) is presented. The retarded rate of the slower (IDP) increase of the rapid phase of Kautsky effect (OIDP) as well as the lower level of QB-nonreducing PS2 reaction centers in HCS plants suggested an accelerated rate of electron flow in the PS2 acceptor side. The response of the antioxidant defense system included enhancement of superoxide dismutase (SOD) activity, total antioxidant activity and content of flavonoids. Changes in thylakoid electron transport chain reactions accompanied with altered oxidative stress-related metabolic activity could be considered as a protective mechanism operating in conditions of combined heavy metal toxicity. [ABSTRACT FROM AUTHOR]

Tropospheric ozone (3) is one of the most widespread atmospheric pollutants in many parts of the world. Elevated ambient O3 concentrations have deleterious effects on the physiological status and productivity of a wide range of plant species. Experiments with controlled O3 fumigation are often performed in order to distinguish O3-induced injury from a wide range of injury symptoms caused by other environmental stress agents. In the present study, branches of common beech (Fagus sylvatica L.) were subjected to O3 fumigation for three days under controlled conditions. Ozone was provided at a concentration of 600 ppb in the course of 6 h during the day. The visible foliar symptoms of injury appeared as small pale green dots on the adaxial leaf surface. By the end of the first day, these dots were spread on the entire leaf surface. The acute O3-induced symptoms developed rapidly as reddish-brown stipple which enlarged covering the entire leaf surface on the third day of O3 exposure. These typical visible symptoms could serve as indicators of the presence of phytotoxic levels of O3 in natural conditions. Ozone fumigation treatment caused a significant decrease in the amount of total chlorophyll as well as metabolic changes in the antioxidant defense system of beech leaves. Elevated total antioxidant and free radical scavenging activities indicated enhanced capacity of the non-enzymatic plant defense system in response to oxidative stress caused by O3-induced generation of reactive oxygen species (ROS). Total flavonoid and anthocyanin contents were also increased. The enhanced activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (PO) can serve as indicators of oxidative burst caused by O3 fumigation in beech leaves. [ABSTRACT FROM AUTHOR]

Medicinal plants of Achillea millefolium group in Bulgarian wild flora are widely used in both traditional medicine and pharmaceutical, cosmetic and nutritive industries. They are intensively collected from the natural habitats, thus leading to a number of negative effects, such as ecological risk of extinction of native sources and high heterogeneity of the collected market samples. We explored the possibilities for field cultivation of wild A. millefolium group species as a promising approach to produce homogenous samples of valuable plants without damage to the natural environment. Our preliminary studies have identified as promising two species of A. millefolium group in Bulgaria - A. collina and A. asplenifolia. The species A. collina and A. asplenifolia, each with two populations, were studied, while cv. "Proa", bred for field cultivation, was used as a standard. Seeds were collected from the natural habitats and those of cv. Proa were purchased from the firm "Pharmasaat GmbH", Germany. Seedlings were produced in a greenhouse and then transferred to the experimental field of the Institute of Plant Physiology and Genetics near Sofia. Plants were harvested at full blossoming stage. Essential oil yield and chamazulene content in the oil, contents of total flavonoids and chlorogenic (3-O-caffeoyl quinic) acid as well as antiradical and antioxidant activities in flower heads were determined. Principal Component Analysis (PCA) of data was performed. The results showed that field-grown plants of the studied A. millefolium group species produced significant amounts of bioactive compounds, particularly flavonoids and chlorogenic acid which highly correlated with the antiradical activity. PCA pointed to the relatedness of populations within each species, and the distant positions of the species. The populations of A. asplenifolia were distinguished by higher contents of total flavonoids, essential oil, chamazulene and chlorogenic acid as well as by higher antiradical and antioxidant activities as compared to A. collina, while being closer by all parameters to cv. "Proa". The data point to A. asplenifolia as a promising species for field cultivation. [ABSTRACT FROM AUTHOR]

In the present study, the effect of excess Zn and Pb ions added to the nutrient solution of hydroponically grown sunflower plants was studied in order to evaluate their impact on the properties of leaf tissue by employing an electrolyte leakage kinetics model. Based on the behavior of model parameters, it was demonstrated that treatment with excess Zn had a stronger effect on leaf leakage kinetics than Pb. This could be attributed to the higher mobility of Zn ions which were more readily transported towards the leaves in comparison to Pb. Ion fluxes through different subcellular compartments, namely apoplast (including cell wall) and symplast (comprising the vacuole and cell membranes) were used to explain the changes in ion leakage kinetics as reflecting the functional status of cellular membranes. [ABSTRACT FROM AUTHOR]

The work is aimed at a detailed study of large-scale helical vortex structures emerging in a high turbulent intensively swirling flow. It was shown that the vortex formed in the chamber by installing diaphragm with shifted outlet is folded into a single-helical vortex. The flow visualization shows that although the vortex axis performs slow oscillations (precession), on average this structure is fixed in space. The velocity fields were measured with the aid of a nonintrusive method of flow diagnostics (PIV). Verification of the calculation results obtained using a LES simulation was performed based on measured experimental data to confirm the correctness of the chosen mathematical modelling approach. It has been asserted that the investigated regimes are in a self-similarity area relative to Reynolds number.

In this study, the contribution of nonenzymatic (ascorbate, glutathione) and enzymatic antioxidants (superoxide dismutase, catalase, glutathione reductase, glutathione S-transferase) in the first hours of recovery of the resurrection plant Haberlea rhodopensis from drought- and freezing-induced desiccation was assessed. The initial stage of recovery after desiccation is critical for plants, but less investigated. To better understand the alterations in the activity of antioxidant enzymes, their isoenzyme patterns were determined. Our results showed that ascorbate content remained high during the first 9 h of rehydration of desiccated plants and declined when the leaves' water content significantly increased. The glutathione content remained high at the first hour of rehydration and then strongly decreased. The changes in ascorbate and glutathione content during recovery from drought- and freezing-induced desiccation showed great similarity. At the beginning of rehydration (1-5 h), the activities of antioxidant enzymes were significantly increased or remained as in dry plants. During 7-24 h of rehydration, certain differences in the enzymatic responses between the two plant groups were registered. The maintenance of a high antioxidant activity and upregulation of individual enzyme isoforms indicated their essential role in protecting plants from oxidative damage during the onset of recovery.

Maintaining a strong antioxidant system is essential for preventing drought-induced oxidative stress. Thus, in the present study we investigated the role of some non-enzymic and enzymic antioxidants in desiccation tolerance of Haberlea rhodopensis. The effects of high light upon desiccation on antioxidant capacity was estimated by comparing the response of shade and sun plants. The significant enhancement of the antioxidant capacity at 8% RWC corresponded to an enormous increase in flavonoid content. The important role of ascorbate-glutathione cycle in overcoming oxidative stress during drying of H. rhodopensis was established. The antioxidant capacity increased upon dehydration of both shade and sun plants but some differences in non-enzymatic and enzymatic antioxidants were observed. Investigations on the role of polyphenols in desiccation tolerance are scarce. In the present study the polyphenol profiles (fingerprints) of the resurrection plant Haberlea rhodopensis, including all components of the complex are obtained for the first time. It was clarified that the polyphenol complex of H. rhodopensis includes only two types of glycosides - phenylethanoid glucosides and hispidulin 8-C-glucosides. Upon desiccation the polyphenol content increase and the main role of phenylethanoid glucosides in the protection of H. rhodopensis was revealed., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

The aim of the present work was to study the response of two sunflower genotypes (cultivated sunflower Helianthus annuus cv. 1114 and newly developed genotype H. annuus × Helianthus argophyllus) to Pb medium-term stress and the role of exogenously applied EDTA in alleviating Pb toxicity in hydroponics. Plant growth, morpho-anatomical characteristics of the leaf tissues, electrolyte leakage, total antioxidant activity, free radical scavenging capacity, total flavonoid content, and superoxide dismutase isoenzyme profile were studied by conventional methods. Differential responses of both genotypes to Pb supplied in the nutrient solution were recorded. Pb treatment induced a decrease in the relative growth rate, disturbance of plasma membrane integrity, and changes in the morpho-anatomical characteristics of the leaf tissues and in the antioxidant capacity, which were more pronounced in the cultivated sunflower H. annuus cv. 1114. The new genotype demonstrated higher tolerance to Pb when compared with the cultivar. This was mainly due to increased photosynthetically active area, maintenance of plasma membrane integrity, permanently high total antioxidant activity, and free radical scavenging capacity as well as total flavonoid content. The addition of EDTA into the nutrient solution led to limitation of the negative impact of Pb ions on the above parameters in both genotypes. This could be related to the reduced content of Pb in the roots, stems, and leaves, suggesting that the presence of EDTA limited the uptake of Pb. The comparative analysis of the responses to Pb treatment showed that the deleterious effect of Pb was more pronounced in the cultivated sunflower H. annuus cv. 1114. The new genotype H. annuus × H. argophyllus was more productive and demonstrated higher tolerance to Pb medium-term stress, which could indicate that it may possess certain mechanisms to tolerate high Pb concentrations. This character could be inherited from the wild parent used in the interspecific hybridization. The ability of EDTA to prevent Pb absorption by the plants could underly the mechanism of limiting of the negative impact of Pb ions. Hence, EDTA cannot be used to enhance Pb absorption from nutrient solution by sunflower plants for phytoremediation purposes.