Abstract: [Objective] LBD(LATERAL ORGAN BOUNDARIES DOMAIN) transcription factors play a potential role in plant secondary growth. The aims were to clone the cDNA of LBDs from Taxus chinensis and reveal their potential regulatory role in tissues regeneration after bark girdling by investigating the expression profiles of these LBDs. [Method] According to the sequences of TcLBDs genes obtained from the transcriptome database of the regeneration tissues after bark girdling in T. chinensis, specific primers were designed. The two LBD genes were isolated using reverse transcription-polymerase chain reaction (RT-PCR). Bioinformatic characteristics of the cloned TcLBDs were analyzed using online service. Lastly, the expression profiles of these genes in different tissues and at different regeneration stages after bark girdling were analyzed by semi-quantitative RT-PCR and quantitative real-time PCR (qRT-PCR) respectively. [Result] The results showed that the cDNA of TcLBD1 contained a 549 bp open reading frame (ORF) in length which encoded polypeptide of 182 amino acids, and TcLBD6 contained a 687 bp ORF encoding 228 amino acid residues. The molecular weights of TcLBD1 and TcLBD6 encoded protein were 19.97 kDa and 25.13 kDa, respectively. The sequences analysis showed that the amino acid sequences of TcLBD1 and TcLBD6 contained one specific conserved LOB motifs in N-terminal and were classified into class Ⅰ of LBD transcription factors, both of them shared 55.2% and 57.9% sequence similarity in nucleotide and amino acid, respectively, and had high identity with each other in secondary structure of protein. Phylogenetic tree analysis suggested that TcLBD1 could be clustered together with protein (ABK21479) of Picea sitchensis and they are closest in genetic relationship, TcLBD6 could be clustered with protein ASYMMETRIC LEAVES2/LBD6 of Arabidopsis thaliana. The analysis of tissues expression patterns showed that the transcript abundance of TcLBD1 was higher in stems and xylem with cambium than that in roots, leaves, phloem with cambium; while TcLBD6 was mainly expressed in roots and stems. Through analysis of the expression patterns in regeneration tissues after bark girdling, the mRNA expressions of TcLBD1 appeared sharply expression after 6 days bark girdling and showed a continuously upregulated pattern, that of TcLBD6 were found to increase notably after 18 days and show a rising trend in the following periods.[Conclusion] Three TcLBDs genes were cloned from T. chinensis, and their expressions were regulated in regeneration processes after bark girdling. Our results demonstrated that TcLBD1 and TcLBD6 might play a regulatory role in bark regeneration after bark girdling in T. chinensis.

Key words: Taxus chinensis, LBD, transcription factor, bioinformatics analysis, gene expression