Figure 7.

Mutational analysis identifying regions of the CBF2 promoter involved in cold-regulated gene expression. A, CBF2::GUS promoter constructs with mutations in boxes IV (mboxIV), V (m2), and VI (m3 and m4) were tested for cold responsiveness by transferring plants from 22°C (W) to 4°C (C) for 2 h and determining GUS transcript levels by RNA-blot hybridization. rRNA stained with ethidium bromide was used to compare loading. B, Sequence corresponding to wild-type and mutated (m2, m3, m4, and mboxIV) CBF2::GUS promoter constructs. Regions identified as required for cold induction are underlined and designated ICEr1 and ICEr2.