Identification of a cold-inducible gene encoding calmodulin-binding protein from Eucalyptus dunnii through suppression subtractive hybridization

Low temperature is the main limiting factor for cultivation expansion, fast growth, and high yield of Eucalyptus species. To investigate the mechanism of their cold tolerance, a cDNA subtraction library representing the cold-induced genes of Eucalyptus dunnii was constructed using suppression subtractive hybridization (SSH) technique. A gene encoding a calmodulin-binding protein ( CaMBP ) was identified from the SSH library, and the expression pattern of CaMBP under cold stress was further evaluated through reverse transcription — quantitative polymerase chain reaction (RT-qPCR). The expressions of EguCBF1a and EdCaMBP increased already after 4 h of the cold stress, supporting the idea that the CaMBP gene may have a function in the survival of Eucalyptus during winter. A full-length mRNA sequence of 1 808 bp was obtained via a rapid amplification of cDNA ends method, and the sequence was subsequently deposited to GenBank (accession No. JX401571). The CaMBP cDNA of E. dunnii contained a single open reading frame of 1 362 bp, a 5t’ untranslated region of 175 bp, and a 3t’ untranslated region of 268 bp. Multiple sequence alignment and phylogenetic analysis indicated that CaMBP of E. dunnii shared 56 to 84 % identities with the CaMBP s of other plants and was similar to that of Ricinus communis , Medicago truncatula , and Gossypium hirsutum .