Impact of cold acclimation, de-acclimation and re-acclimation on carbohydrate content and antioxidant enzyme activities in spring and winter wheat

The capability of overwintering in winter cereals results in their ability to withstand cold hardening during the autumn or de-hardening during temporary warm spells and then to withstand re-hardening when cold waves return. The present study was carried out to evaluate quantitative changes in the carbohydrate content in leaves, hydrogen peroxide (H 2 O 2 ) production, and the activities of guaiacol peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). The effects were studied on a less coldhardy spring cultivar Pishtaz (LT 50 = –6°C), and a cold-hardy winter cultivar CDC-Ospray (LT 50 = –20°C) of wheat under cold acclimation (20 days at 4°C), interrupted by de-acclimation (10 days at 25°C) and then followed by re-acclimation conditions (10 days at 4°C). Hardening conditions induced the accumulation of carbohydrates in both cultivars and the de-acclimated plants exhibited a significant reduction. The activities of tested antioxidative enzymes were altered in both cultivars during the investigated periods. Cold acclimation induced elevation in the activities of SOD, APX, CAT and GPX in leaves of winter wheat, whereas in spring wheat a considerable increase was only recorded after the de-acclimation period. The results of the present experiment agreed with the conclusion that in hardy winter wheat cold acclimation may be associated with an improvement of the scavenging capacity for reactive oxygen species and carbohydrate accumulation in leaves.