Impact of cold-induced antioxidant activity on frost resistance in androgenic <em>Festulolium</em> genotypes

The aim of the study was: (i) to state if selected in the field conditions androgenic Festulolium genotypes are diverse in frost tolerance, and (ii) to investigate if changes in anitoxidant activity could be recognized as a physiological marker of this type tolerance. Antioxidative system induced by prehardening (12°C) and hardening (2°C) temperatures was investigated in 6 androgenic genotypes generated from a Festuca pratensis × Lolium multiflorum (2n = 4x = 28) amphidiploid hybrid (four genotypes derived from the F1 hybrids, and two genotypes derived from the Festulolium cultivar ‘Rakopan’). The electrolyte leakage, frost resistance expressed as the values of temperature causes 50% damages (LT50), the activities of superoxide dismutase (SOD), catalase (CAT), non-specific peroxidase (PX) and ascorbate peroxidase (APX) were measured. The results obtained indicated weak diversity of frost tolerance among studied androgenic genotypes. Only the one genotype was chosen as the most resistant to frost, while the other genotypes demonstrated no significant differences in values of LT50 coefficient recorded after hardening. Prehardening temperature of 12°C caused an increase in cell membrane permeability in all genotypes studied. After hardening ion leakage from cells declined up to the control level. Generally, cold activated SOD, PX and APX in leaves of the genotypes studied, and inhibited strongly CAT activity. The most frost tolerant genotype was characterized by high PX activity after hardening process. Abbreviations: APX – ascorbate peroxidase, CAT – catalase, EDTA – ethylenediaminetatraacetic acid, LT50 – letal temperature causing 50% membrane cell damages, NBT – nitroblue tetrazolium, PPFD – photosynthetic photon flux density [μmol m-2 s-1], PX – non-specific peroxidase, RH – relative humidity, ROS – reactive oxygen species, SE – standard error, SOD – superoxide dismutase