Figure 2.

Desensitization and resensitization of the regulatory circuitry controlling accumulation of CBF transcripts. A, Plants were subjected to repeated transfer between 20°C (W) and 4°C (C), and CBF and COR15a transcript levels were determined by RNA-blot hybridization. B, CBF transcript levels of in plants that were cold acclimated at 4°C (C) for 14 d, returned to warm temperatures for the indicated times, and then subjected to a cold shock (WCS) at 4°C. CBF transcript levels were also determined in cold-acclimated plants (14 d) that were transferred (Xfer) to 0°C or –5°C 2 h. C, CBF and COR15a transcripts levels in plants cooled at 2°C h^–1. Plants were held at 10°C for 48 h before cooling to 4°C. The probe used hybridized with CBF1, 2, and 3 transcripts. rRNA stained with ethidium bromide was used to compare loading in each experiment.