Investigation of biochemical function of selenium and its influence on the content of protein fractions and peroxidase activity in maize seedlings

The release of elemental selenium on the root surface of maize (Zea mays L., variety Krasnodarskii 29/AMV) seedlings observed in response to the addition of selenium-organic preparation DAFS-25 (diacetophenonyl selenide) to the nutrient Knop solution and accompanied by inhibition of growth of the roots was investigated. This process was completely suppressed after the addition of cysteine to the above solution containing 10–²g/L DAFS-25, with the inhibiting effect was attenuated as well. In addition, DAFS-25 exerted impact on nitrogen exchange in the plants as judged by elevating the protein fraction of albumins in the roots almost by a factor of two due to at the expense of decreasing the content of glutelin, prolamine, and globulin fractions by 43, 25, and 26%, respectively. In the case of the action of DAFS-25 in combination with cysteine the quantitative composition of the above proteins very closely resembled that of the control plants indicating that cysteine behaves as antidote. It was found that DAFS-25 exerted a similar action on the content of albumins in the above-ground part of maize seedlings where this value drastically increased (by a factor of 4.5) on the background of total protein content elevation. In addition, this preparation at the highest concentration tested stimulated the activity of peroxidase in both the roots (by 63%) and the above-ground part of seedlings (by 112%). However, this effect of DAFS-25 was strongly inhibited after addition of cysteine to the nutrient solution. Evaluation of selenium content in the same parts of the control seedlings showed that they contain only a little amount of this element. The highest content of selenium in the above plant tissues was found after addition of DAFS-25 to the nutrient solution that provides evidence for its decomposition directly on the surface of the roots. Such an action of DAFS-25, like its impact on the peroxidase activity, was markedly attenuated in the presence of cysteine.