低温胁迫下拟南芥CBF1超表达突变体胞质中Ca^(2+)浓度的变化

Intracellular Ca^(2+) Changes During Cold Stress in CBF1-overexpress Arabidopsis

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。

Abstract Plant growth is greatly affected by low temperature. Cold shock elicits an immediate increase in free Ca^2＋ concentration in plant cells. Here, we focused on the expression of CBF1 under low temperature treatment and the cold-triggered Ca^2＋ responses in CBFl-overexpressing Arabidopsis. CBF1 was induced by low temperature. To address the relation between CBF1 and Ca^2＋ we measured cold-triggered Ca^2＋ responses in CBFl-overexpressing Arabidopsis. CBFl-overexpressing plants exhibited a higher mean peak Ca^2＋ concentration than did wild-type plants, but the Ca^2＋ 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 Ca^2＋ concentration was inhibited. The cytoplasmic Ca^2＋ concentration in CBF1-overexpressing and wild-type plants decreased to the same level. Thus, the results suggest that Ca^2＋ 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 Ca^2＋ concentration.