Plants which survive subzero temperatures in winter enhance freezing tolerance upon exposure to non-freezing temperature, a phenomenon termed cold acclimation. Although the mechanism of enhanced freezing tolerance has been examined at the molecular level, its understanding is still incomplete. Recently, Arabidopsis thaliana ecotypes are collected from all over the world. By studying these ecotypes, further knowledge on freezing tolerance could be obtained. To identify novel genes involved in the freezing tolerance after cold acclimation, we developed the screening system to measure the survival rate quantitatively based on Fv/Fm value. With this method, we isolated the ecotypes with higher or lower freezing tolerance than that of Col-0 ecotype. Our method identified ecotypes which show the lower freezing tolerance, including C24 and Cvi, which are already known as ecotypes with lower freezing tolerance.
