低温严重影响植物的生长, 低温刺激可引起植物细胞中Ca²⁺浓度迅速升高。以拟南芥(Arabidopsis thaliana) CBF1 超表达突变体为材料, 研究了低温处理时CBF1基因的表达情况及胞质Ca²⁺的浓度变化。结果表明, CBF1本身可受低温诱导。同时将水母发光蛋白基因转入该拟南芥突变体中并检测Ca²⁺的浓度变化, 发现低温刺激时突变体细胞质中Ca²⁺的浓度变化幅度明显高于野生型, 但液泡的胞质面两侧Ca²⁺的浓度变化相似。用EGTA和LaCl₃处理拟南芥后, 胞质Ca²⁺的浓度升高被抑制, 并且CBF1突变体及对照胞质中的Ca²⁺浓度下降到同一水平。上述结果表明, Ca²⁺参与了CBF1应答低温信号的转导过程, 并且CBF1超表达突变体可能是通过提高胞质Ca²⁺浓度来提高植物的抗低温胁迫能力。

Plant growth is greatly affected by low temperature. Cold shock elicits an immediate increase in free Ca²⁺ concentration in plant cells. Here, we focused on the expression of CBF1 under low temperature treatment and the cold-triggered Ca²⁺ responses in CBF1-overexpressing Arabidopsis. CBF1 was induced by low temperature. To address the relation between CBF1 and Ca²⁺, we measured cold-triggered Ca²⁺ responses in CBF1-overexpressing Arabidopsis. CBF1-overexpressing plants exhibited a higher mean peak Ca²⁺ concentration than did wild-type plants, but the Ca²⁺ signature adjacent to the vacuolar membrane increased to similar levels in both plants. In Arabidopsis seedlings pretreated with EGTA or LaCl₃, the cold shock-induced increase of Ca²⁺ concentration was inhibited. The cytoplasmic Ca²⁺ concentration in CBF1-overexpressing and wild-type plants decreased to the same level. Thus, the results suggest that Ca²⁺ is involved in the process of the CBF1 response to low-temperature signal transduction, and the CBF1-overexpress may enhance freezing tolerance of plants by increasing the cytoplasmic free Ca²⁺ concentration.