Indices of antioxidant and osmoprotective systems in seedlings of winter wheat cultivars with different frost resistance

The functioning of the stress-protective systems of wheat under the action of cold at the early stages of plant development remains poorly studied. The aim of this work was a comparative study of antioxidant activity and the content of sugars and proline as indicators of osmoprotective activity during cold adaptation of seedlings of seven winter bread wheat (Triticum aestivum L.) cultivars that differ significantly in frost resistance. The 3-day-old etiolated seedlings were hardened at 2°C for 6 days and then frozen for 5 h at -6 or -9°C. Two days after freezing, the survival of seedlings was assessed by their ability to grow. A decrease in ROS content, an increase in the activity of antioxidant enzymes catalase and guaiacol peroxidase and accumulation of sugars in the shoots of high-frost-resistant cultivars during hardening were detected. The absolute values of catalase and guaiacol peroxidase activity correlated positively with the frost resistance of seedlings. The negative correlation between the frost tolerance of the cultivars and the accumulation of proline in the seedlings during hardening was recorded. The possibility of using the studied biochemical indices for frost resistance screening of winter wheat varieties at the seedling stage was stated. Keywords: antioxidant system, cold hardening, frost resistance, osmolytes, oxidative stress, Triticum aestivum