Localization and ligand environment of lead in pennycress (Noccaea praecox Wulf)

Svinec (Pb) se naravno pojavlja znotraj zemeljske skorje, v zadnjem času pa se je na industrijskih območjih njegova koncentracija v zgornjih plasteh tal povečala. V vodi je slabo topen, v tleh pa se veže na organske ali koloidne snovi. Je zelo strupen in v rastlinah nima poznane biološke vloge. Da bi se rastline ubranile škodljivih učinkov Pb, so razvile različne mehanizme razstrupljanja in tolerance. V magistrskem delu smo preučili vpliv različnih koncentracij Pb na biokemijske in fiziološke lastnosti ranega mošnjaka ter lokalizacijo in vezavne oblike Pb v tkivih. Rastline, ki so rasle na hidroponiki, smo izpostavili različnim koncentracijam Pb, uporabili smo tudi kontrolne rastline, ki niso bile izpostavljene Pb. Med poskusom smo merili fotokemično učinkovitost fotosistema II (FU FS II). Na koncu poskusa smo stehtali svežo in suho maso rastlin in pripravili različne vzorce, v katerih smo določali fotosintezna barvila, oksidativni stres, privzem, prenos in porazdelitev hranilnih snovi, lokalizacijo Pb z metodo LA-ICP-MS in mikro.PIXE ter vezavne oblike Pb z metodo Pb-L3 XANES. Ugotovili smo, da visoke koncentracije Pb (100 mg/L) povzročajo motnje v rasti in zmanjšajo tvorbo suhe mase, zavirajo sintezo klorofila a in b ter karotenoidov in negativno vplivajo na privzem in porazdelitev nekaterih elementov. Ugotovili smo tudi, da fotosintezni sistem ni bil prizadet in da nizke koncentracije Pb pozitivno vplivajo na FU FS II, sintezo klorofilov in karotenoidov. Oksidativne poškodbe kontrolnih rastlin so bile podobne poškodbam pri visokih koncentracijah Pb. Svinec se je kopičil večinoma v povrhnjici, vezal pa se je na kisikove in fosfatne ligande. Delo bo pripomoglo k razumevanju različnih mehanizmov tolerance ranega mošnjaka na Pb in nadaljnjemu preučevanju njegove lokalizacije ter vezavnih oblik.Lead (Pb) occurs naturally within the earth\u27s 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\u27s 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