Figure 8.

Respiratory burst oxidase homolog D (AtRBOHD) mediates melatonin- or Ca²⁺-induce freezing tolerance in Arabidopsis. (A) Freezing phenotypes. (B) Survival rates. (C) The relative expression of C-repeat binding factor 1 (AtCBF1) and its regulons, including cold-responsive gene 47 (AtCOR47), early responsive to dehydration 10 (AtERD10), and cold induced gene 1 (AtKIN1) under cold stress at 4 °C. Three-week-old wild-type (WT) and Atrbohd mutant seedlings grown on the ½ MS medium were treated with 10 µM melatonin (MT) or 1 mM CaCl₂ (Ca²⁺). After 12 h, the seedlings were subjected to freezing at −10 °C for 1 h and then recovered at 22 °C for 5 days or exposed to chilling at 4 °C for 24 h. Relative expression of genes in untreated WT plants was set as 1.0. Data show the means of three replicates ± standard deviation (SD). The different letters denote significant difference at p < 0.05 according to Turkey’s test.