Changes in cold tolerance and the mechanisms of acclimation of photosystem II to cold hardening generated by anther culture of Festuca pratensis x Lolium multiflorum cultivars

Mechanisms of photosynthetic acclimation to cold were investigated on androgenic plants generated from Festuca pratensis x Lolium multiflorum (4x) cultivars Felopa and Sulino and on parental material. Photosynthetic acclimation and resistance to high-light induced inactivation of PSII at low temperature were studied using chlorophyll fluorescence techniques in relation to winter hardiness, frost resistance and cold acclimation in field and controlled conditions. In the field increased energy dissipation before winter through a lower maximum quantum yield of PSII was correlated with improved winter survival of these genotypes. In controlled conditions winter hardy plants were more resistant to cold-induced inactivation of PSII. During cold acclimation of winter hardy plants nonphotochemical quenching (NPQ) increased, except in one genotype where photochemical quenching increased. The use of androgenic lines revealed gene combinations that determined alternative photoinhibition avoidance mechanisms in the parental genome. Increased dissipation of light energy is an alternative process to the increased photosynthetic capacity reported previously to be the main mechanism of photosynthetic acclimation to cold in herbaceous Poaceae.