Abstract:

Two CBF genes named EgrCBF 1 and EgrCBF 2 (GenBank No. JQ068827; JQ068828)were isolated from Eucalyptus grandis seedlings under low temperature. Sequence analysis showed that EgrCBF 1 and EgrCBF 2 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 EgrCBF1 and EgrCBF2 protein shared 91% and 80% homology with EguCBF 1 a. Spatial expression analyses showed that EgrCBF 1 expressed mainly in leaves and roots while EgrCBF 2 expressed in all leaves, stems and roots. qRT-PCR result of EgrCBF 1 and EgrCBF 2 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 EgrCBF 1 and EgrCBF 2 expression under 100 μmol·L^-1ABA, 200 mmol·L^-1NaCl and drought were also analyzed. The results showed EgrCBF 1 was up-regulated under drought stress and ABA treatment, while the expression of EgrCBF 2 increased under drought and salt stress.

Key words: Eucalyptus grandis, CBF, cold, ABA, drought, salt