Cadmium treatment effects on the growth and antioxidant system in barley plants under optimal and low temperatures | UČINKI OBRAVNAVE S KADMIJEM NA RAST IN ANTIOKSIDACIJSKI SISTEM JEČMENA PRI OPTIMALNIH IN NIZKIH TEMPERATURAH

anglais. The cadmium effect (100 μM) on the barley (Hordeum vulgare L.) growth, the content of HvCu/ZnSOD, HvCAT2 and HvPRX07 transcripts and the antioxidant enzymes activity (SOD, CAT and PRX) in roots and leaves of seedlings under optimal (22 °C) and low (4 °C) temperatures were studied. Exposure to cadmium at 22 °C did not inhibit the plants’ growth. In this case, the rate of the oxidative processes in the cells remained at the control level. This was achieved by a corresponding increase of the gene transcripts and the antioxidant enzymes activity in roots and leaves. In contrast, exposure to cadmium at 4 °C inhibited the seedlings’ growth despite of the lower metal content in the plants. Moreover the rate of lipid peroxidation in the roots and leaves increased significantly. It is assumed that this effect was connected with the accumulation of excess amounts of hydrogen peroxide due to a misbalance between its generation and neutralization. This assumption is confirmed by the obtained data, according to which the level of HvCu/ZnSOD expression and the total activity of SOD increased significantly under exposure to cadmium at 4 °C, although HvCAT2 and HvPRX07 transcripts and CAT and PXR activity did not rise.

slovène. Preučevan je bil učinek kadmija (100 μM) na rast ječmena (Hordeum vulgare L., vsebnost HvCu/ZnSOD, HvCAT2 in HvPRX07 transkriptov in na aktivnost antioksidacijskih encimov (SOD, CAT in PRX) v koreninah in listih sejank pri optimalni (22 °C) in nizki temperaturi (4 °C). Izpostavitev kadmiju pri 22 °C ni zavrla rasti rastlin. V teh razmerah so oksidacijski procesi v celicah ostali na ravni kontrole, kar je bilo doseženo s povečanjem ustreznih prepisov genov in aktivnostjo antioksidacijskih encimov v koreninah in listih. Nasprotno je izpostavitev kadmiju pri 4 °C zavrla rast sejank kljub manjši vsebnosti kovine v rastlini. Peroksidacija maščob v koreninah in listih se je značilno povečala. Domnevamo, da je bil ta učinek povezan s kopičenjem presežnih količin vodikovega peroksida zaradi neuravnoteženosti njegovega nastanka in nevtralizacije. To domnevo potrjujejo podatki, da sta se ekspresija HvCu/ZnSOD in celopkupna aktivnost SOD značilno povečali pri izpostavitvi kadmiju pri 4 °C, pri čemer vsebnosti HvCAT2 in HvPRX07 transkriptov in aktivnosti CAT ter PXR niso narasle.