Molecular cloning, characterization, and functional analysis of CcBBM gene from camphor tree (Cinnamomum camphora L.)

Abstract

Cloning and functional analysis of CcBBM gene. Baby boom (BBM), as a transcription factor of AP2/ERF family, has great potence in promoting somatic embryogenesis. In this study, a BBM gene from somatic embryos of camphor tree (Cinnamomum camphora L.), named CcBBM, was cloned and characterized. A partial fragment of 560 bp of CcBBM was amplified by degenerate PCR based on the two conserved AP2 domains of other annotated BBMs. Full-length cDNA of CcBBM was obtained by a cloning strategy combing degenerate PCR and RACE technique. The open-reading frame of CcBBM is 2169 bp in length, which encodes 722 amino acids. A comparison of the deduced amino acid sequence of CcBBM with BBM from other species showed high similarities, ranging from 51 to 80 %. The mRNA levels of CcBBM in different tissues were detected by semi-quantitative reverse transcription PCR (RT-PCR). CcBBM was expressed in most tissues, with highest expression level in somatic embryos, followed by roots, young fruits and flowers. Ectopic expression of CcBBM gene in Arabidopsis exhibited a variety of deformed and variegated leaves and short roots. No spontaneous somatic embryogenesis was observed in 35S::CcBBM transgenic plants. These results will help us understand the role of CcBBM in somatic embryogenesis in camphor tree.