Figure 4.
OsCRP1 overexpression in rice confers cold tolerance. (a) Relative expression of OsCRP1 in response to cold stress. Two-week-old seedlings were exposed to at 4 °C (low temperature) for the indicated times. OsUbi1 expression was used as an internal control. Values are the means ± SD of three independent experiments. (b) Phenotypes of OsCc1::OsCRP1OX and OsCc1::OsCRP1RNAi transgenic rice plants under cold stress at the vegetative stage. Three independent homozygous OsCc1::OsCRP1OX and OsCc1::OsCRP1RNAi lines and NT control plants were grown in soil for 2 weeks and exposed to cold stress for 3 days, followed by recovery. (c) Survival rate scored 7 days after recovery. Values represent means ± SD of three repeated tests. Asterisks indicate significant differences compared with NT (* p < 0.05, One-way ANOVA). (d) Chlorophyll fluorescence (Fv/Fm) of OsCc1::OsCRP1OX, NT and OsCc1::OsCRP1RNAi plants during a 3-day cold treatment. Fv/Fm values were measured in the dark to ensure sufficient dark adaptation. Data are shown as the mean ± SD (n = 30). (e) ATP contents in leaves of the OsCc1::OsCRP1OX, NT and OsCc1::OsCRP1RNAi plants under before and after cold stress conditions. Ten two-week-old plants were used for each line, and the middle portion of the second leaf from the top was taken for analysis. Data bars represent the mean ± SD of three biological replicates, each of which had two technical replicates. Asterisks indicate significant differences compared with NT (* p < 0.05, One-way ANOVA).