Knockout AtPrx mutants showed increased susceptibilities to cold stress compared with wild type. (A) Confirmation of lack of transcription of AtPrx1, AtPrx22, AtPrx39, and AtPrx69 in each corresponding mutant. (B) Cold-treated AtPrx seedlings displayed increasingly damaged phenotypes after a 2-day recovery period. (C) Quantitative analysis of cold response as determined by the ratio of damaged leaves following cold treatment (bar graph, right) and electrolyte leakage (line graph, left). ANOVA statistical analyses were performed, and significant differences are indicated by P values (*P ≤ 0.6 for damaged leaves, **P ≤ 0.3 for ion leakage). Bar denotes standard deviation.