The Responses of Pro‐ and Antioxidative Systems to Cold‐hardening and Pathogenesis Differ in Triticale ( x Triticosecale Wittm.) Seedlings Susceptible or Resistant to Pink Snow Mould ( Microdochium nivale Fr., Samuels & Hallett)

Two winter triticale ( x Triticosecale Wittm.) cultivars, Magnat (susceptible to pink snow mould) and Hewo (relatively resistant), were used in a model system to test the effect of prehardening and different cold‐hardening regimes on pro‐ and antioxidative activity in seedling leaves. The concentration of hydrogen peroxide and the activity of total superoxide dismutase, catalase, peroxidase and ascorbic peroxidase were analysed spectrophotometrically. As there has been no previous analysis of the pro/antioxidative reaction of cereals to Microdochium nivale infection has been undertaken to‐date, this is the first in the series describing our results. We confirmed that both exposure to abiotic stress of low temperature and subsequent low light intensity, as well as biotic stress of M. nivale infection, change the pro‐ and antioxidative activity in model plants. Genotypes differed substantially in their hydrogen peroxide content: susceptible cv. Magnat generally showed higher levels during all the experiments. This result can lead to the conclusion that cv. Magnat is also more susceptible to low temperature and low light intensity than cv. Hewo. Simultaneous measurements of antioxidative activity indicated that the increased activity of catalases and peroxidases and the consequent lower H 2 O 2 level are correlated with a higher resistance to low temperature, low light intensity and pink snow mould in triticale seedlings. The higher H 2 O 2 level observed in the susceptible line is likely to be derived from the imbalance of reactive oxygen species production and consumption in this genotype under stress conditions.