Two CBF genes named EgrCBFl and EgrCBF2 ( GenBank No. JQ068827 ; JQ068828 ) were isolated from Eucalyptus grandis seedlings under low temperature. Sequence analysis showed that EgrCBFl and EgrCBFl cDNA had 1 062 bp and 1 203 bp, respectively. The two genes encoded 220 and 196 amino acids, separately and both contained an AP2 domain. The results of homology comparison showed that EgrCBFl and EgrCBF2 protein shared 91% and 80% homology with EguCBFla. Spatial expression analyses showed that EgrCBFl expressed mainly in leaves and roots while EgrCBF2 expressed in all leaves, stems and roots. qRT-PCR result of EgrCBFl and EgrCBFl under 0 ℃ ,2 ℃ ,4 ℃ ,6 ℃ , and 8 ℃ revealed that they were both induced by low temperatures and reached the highest level at 2 ℃ . Time course of the genes expressions at 4 ℃ for 2 h,4 h,8 h,24 h,and 48 h showed that their expressions increased at the first and then decreased. Changes in EgrCBFl and EgrCBFl expression under 100 μmol · L-1 ABA, 200 mmol·L-1 NaCl and drought were also analyzed. The results showed EgrCBFl was up-regulated under drought stress and ABA treatment, while the expression of EgrCBF2 increased under drought and salt stress.%从低温诱导的巨桉幼苗中克隆到2条CBF的全长cDNA序列,命名为EgrCBF1和EgrCBF2,全长分别为1 062 bp和1 203 bp,编码220个氨基酸和196个氨基酸,命名为EgrCBF1和EgrCBF2(GenBank登录号分别为:JQ068827; JQ068828),都包含1个AP2结构域.2个基因编码的蛋白都与冈尼桉中CBF蛋白(DQ241820)具有很高的同源性,与EguCBF1a的同源性分别达到了91％和80％.RT-PCR分析表明,EgrCBF1主要在叶和根中表达,而EgrCBF2在叶、茎和根中都有表达.对不同低温条件(0,2,4,6,8℃)和4℃2,4,8,24,48 h处理下EgrCBF1和EgrCBF2的qRT-PCR分析表明:2个基因都受低温诱导,并在2℃时诱导水平达到最高;4℃下随低温时间的延长,它们的诱导表达特性都呈先升后降的趋势.在100 μmol·L-1 ABA,200 mmol·L-NaCl和干旱处理下,EgrCBF1受ABA和干旱诱导,EgrCBF2则受干旱和高盐胁迫诱导.
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