Lead (Pb) occurs naturally within the earth's crust, but recently, in industrial areas, its concentration in the upper soil layers increased. It is poorly soluble in water and it is bound to organic or colloidal material in the soil. It is very toxic and has unknown biological function in plants. In order to protect from harmful effects of Pb, plants developed various mechanisms of detoxification and tolerance. In the master's thesis, the influence of various concentrations of Pb on the biochemical and physiological properties of pennycress, and the localization and ligand environment of Pb in tissues, were studied. Plants grown on hydroponics were exposed to various concentrations of Pb, the control plants were not exposed to Pb. During the experiment, we measured photochemical effect of photosystem II (FU FS II). At the end of the experiment, we weighed the fresh and dry plants mass and prepared various samples for the determination of photosynthetic pigments, oxidative stress, absorption, mobility and distribution of nutrients, Pb localization using LA-ICP-MS and micro-PIXE method, ligand environment was determined using Pb-L3 XANES method. We have established that high concentrations of Pb (100 mg/L) cause disturbances in growth and reduce the formation of dry mass, inhibit the synthesis of chlorophyll a, b and carotenoids and negatively effect on absorption and distribution of certain elements. The photosynthesis system was not affected and low concentrations of Pb had a positive effect on FU FS II, chlorophylls and carotenoids synthesis. The oxidative damage of the control plants was similar to damage at high concentrations of Pb. Lead accumulated mainly in the epidermis, bound to oxygen and phosphate ligands. This work will help to understand the various mechanisms of Pb tolerance in pennycress and further study of its localization and binding forms.
|
