Changes in the activity of antioxidant enzymes in cereal species during the winter

Summary

The quantity of four enzymes belonging to the antioxidant system (glutathione-S-transferase, ascorbate peroxidase, guaycol peroxidase and glutathione reductase) was determined in plant material raised and hardened under field conditions. One variety each of the winter cereal species wheat, barley, rye, triticale, durum wheat and oats were used for the analy ses. The varieties were sown in small plots at the optimum date (in mid-October) in 1999 and 2000. Plant samples were taken at three dates at the beginning (December), in the middle (January) and at the end (late February or March) of both winters. The exact dates were determined on the basis of the state of hardening and the weather conditions. When the frost resistance of the cereal varieties was determined in the phytotron, the rye variety Motto was found to be the most resistant, followed by the winter wheat Martonvásári 18, the triticale Presto, the durum wheat Odmadur 1, the winter barley Hardy, the winter durum wheat GK Basa, the winter oat varieties, which had very poor frost resistance, and finally the spring oat variety Freja. The activity of the antioxidant enzymes was greater in cereal species with good frost resistance than in those with poor resistance. Differences in enzyme activity were also found within the varieties at different stages of hardening, but these were smaller than those between the varieties. It can be seen from the results that antioxidant enzymes help to protect cereals from the damaging effect of the active oxygen species produced in substantial quantities during exposure to frost.