Variations in the nitrate assimilation, antioxidant system (superoxide dismutase, catalase, ascorbate peroxidase (SOD, CAT, and APX)), and lipid peroxidation (MDA) of Verbascum olympicum (Scrophulariaceae) exposed to cadmium (Cd) in Hoagland's nutrient medium were investigated. The accumulation of Cd and variations in the content of some trace elements (Cu, Mo, Mn, and Zn) and growth parameters as, e.g., the water content, biomass production and chlorophyll and soluble protein content were also studied. Cd treatment (0, 50, 100, and 250 µM Cd) was applied for seven days to eight weeks old seedlings in a growth chamber. Cd accumulated predominantly in the roots of V. olympicum, and the contents of Zn and Cu in the leaves and roots increased with the increasing Cd concentration. We found that increasing the Cd dosage inhibited the activity of nitrate assimilation enzymes and reduced the protein content, water content, and biomass production in the roots and leaves and the chlorophyll content in the leaves. Oxidative stress was confirmed by an increasing level of MDA in the seedlings. We concluded that this species has a powerful antioxidative defence system against Cd stress since SOD, CAT, and APX activities were induced.
Verbascum olympicum Boiss. (Scrophulariaceae) were studied as a candidate plant for remediating the Ni polluted soils. The metabolic responses, such as nitrate assimilation (nitrate reductase and glutamine synthetase activity) and antioxidant system activity [superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity], of this species exposed to nickel in Hoagland's nutrient medium were investigated as remediation performance parameters. The accumulation of nickel and the variations in the content of some elements (B, Cu, Fe, Mg, Mn, Mo and Zn) and some growth parameters, such as the water content, biomass production, and contents of chlorophyll and soluble protein, were also examined. The accumulation of Ni in both the roots and leaves varied depending on the exposure times and doses. Increased oxidative stress was suggested by the increases in the activities of SOD, CAT and APX. Although some element contents were inhibited by Ni treatments, these inhibitory effects was decreased depending on the time, and even these elements are accumulated in roots. These results are the novelties in the use of this species in biotechnology.
This paper is aimed to investigate the effects of some terricolous lichens on soil bacteria's growth in natural conditions. It is focused on species of bacteria and also on numbers of colony of soil specimens that were taken from substrates of three different terricolous lichen species. Peltigera rufescens (Weiss) Humb., which has not secondary metabolites, did not show an inhibition effect on soil bacteria. However, Peltigera neckerii Hepp ex Müll. Arg., which has secondary metabolites, has a negative effect on soil bacteria's growth. Besides, it was observed that Cladonia rangiformis Hoffm., which has many kinds of secondary metabolites, has the highest inhibition effect among the studied species. For this reason, we think that in the next researches, it is convenient to investigate elaborately by soil analysis the effect of lichen's secondary metabolites that have an effect on soil mineralization, on soil bacteria's growth.
Sakarya is famous for cucurbit productions in Turkey and cucurbits can grow as big as 560 kg of weight per fruit in its agricultural areas. There is no or limited information about contaminant levels and profiles of the agricultural fields in Sakarya. The purpose of this study is to investigate the levels of polycyclic aromatic hydrocarbons (PAHs) (naphthalene, phenanthrene, pyrene, and fluoranthene) and heavy metal (As, Cd, Cu, Cr, Ni, Pb, Zn) concentrations of the selected fields. Total 33 soil samples were collected from 12 counties of Sakarya where both cucurbits have been produced and organochlorine pesticides have been applied to the fields for more than 30 y during the historical plantation periods. Heavy metal and PAH contents in the soil samples were measured by an Inductively Coupled Plasma Emission Spectroscopy and a Gas Chromatography-Mass Spectrometry. The highest phenanthrene, pyrene, and fluoranthene concentrations were measured as 63.50 ng/g, 134.34 ng/g, 140.0 ng/g, respectively in the soil samples from Geyve County. Cu, Ni, and Cr concentrations were measured as 108.2 mg/kg, 219.9 mg/kg, and 173.1 mg/kg, respectively in Geyve's samples which were also the highest and 2-7 times more than the limit values given in the Turkish Soil Pollution Control Regulation. Precautions need to be taken for Sakarya's agricultural fields which are an important milestone of Turkey's cucurbit and fruit productions since the contaminants can be accumulated in the fruits and edible parts of the plants.
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