Cold stress tolerance assays

For freezing tolerance assays, 2-week-old Arabidopsis plants growing in soil under control conditions (non-acclimated) or exposed 7 additional days to 4°C (cold acclimated) were transferred to a freezing chamber set to 4°C for 30 min in darkness. Subsequently, temperature was allowed to decrease at a rate of – 1°C per 30 min until reaching the final desired freezing temperature, which was maintained for 6 h. Then, temperature was increased to 4°C at the same rate and thawing was allowed for 12 h before returning plants to control conditions for recovering. Tolerance to freezing was determined as the percentage of plants surviving after one week of recovery.