Effect of cadmium and titanium-ascorbate stress on biologically active compounds in wheat seedlings

The harmful processes caused by heavy metals are serious problems not only for useful plants but, if they enter the food chain, for consumers as well. This is why it is essential to clarify biochemical processes. The effect of cadmium and combined cadmium and titanium-ascorbate was exami ned on wheat seedlings (Triticum aestivum L.). The one-week-old hydroponica lly-grown seedlings of wheat were exposed to Cd2+ (10(-7) M, 10(-3) M) and Cd2+(10(-7) M, 10-3 M) + titanium-ascorbate (5 ng/cm(3)) stresses. The stre ss effects were followed by changes in the free amino acid and polyamine co ntents and the peroxidase enzyme activity in roots and shoots. The free amino acid content was determined by ion-exchange liquid chromatog raphy. The polyamine content was identified by OPLC (over-pressured layer c hromatography). Peroxydase activity (U/mg protein) was measured by the spec trophotometric method. The results showed significant differences between the two plant organs (ro ot and shoot) with respect to the biochemical response to the applied stres s. The total free amino acid content of the shoot samples was higher than that of the roots. Cadmium treatment at the higher concentration caused the hig hest accumulation of total amino acid content in both the shoots and roots. Among the amino acids the threonine, scrine+ (Scr+Asn+Gln), glutamic acid, proline, alanine, valine, isoleucine, leucine, histidine, lysine and argin ine concentrations showed the most significant changes. The different effects of cadmium and the combined cadmium+titanium-ascorbat e treatment can be characterised based on the typical accumulation of polya mines in the two organs of wheat seedlings. Agmatine accumulation was obser ved in the control shoot sample while in the shoot sample treated with Cd2 (10-7 M) combined with titanium-ascorbate, putrescine tended to accumulate . In the roots only putrescine increased significantly. Peroxidase activity was more significant in the root samples than in the sh oot samples. The highest peroxidase activity was measured in the ease of th e Cd2+ (10(-3) M) treatment in the roots. Titanium-ascorbate treatment seem ed to reduce the negative effects of heavy metal pollution in wheat seedlin gs. On the basis of the results it can be stated that the heavy metal stress ca used typical biochemical changes in wheat seedlings. Further research is ne eded to find out the relationship between the heavy metal stress and the ch anges in free amino acid and polyamine contents as well as in peroxidase ac tivity.