Cloning of LjCYC1 gene and nuclear localization of LjCYC1 protein in Lotus japonicus

The LjCYC1 (Lotus japonicus Cycloidea-like 1) gene, a homolog of CYC (Cycloidea) belonging to the TCP [TB1(teosinte branched 1), CYC, PCFs (PCF1 and PCF2)] gene family and encoding a predicted transcription factor and being proposed controlling different aspects of plant development, was isolated from the papilionaceous plant Lotus japonicus by screening the genomic DNA library, in order to test the functional conservation and divarication of CYC-like genes in legume. Sequence analyses indicate that LjCYC1 gene contains two exons and one intron and encodes a 370-AA peptide LjCYC1. The putative protein, LjCYC1, contains a TCP domain and an R domain, being a member of the CYC/TB1 subfamily of TCP family, and has 39.0% identity with and 42.6% similarity to CYC. LjCYC1-cDNA was cloned through RT-PCR. Different regions of the LjCYC1-cDNA were fused with the report gene GUS and then the fused constructs were transiently expressed in the onion epidermal cells through particle bombardment. Results of GUS and DAPI staining showed that the chimeric proteins with TCP domain were localized within the nucleus, confirming that LjCYC1 may act as a transcription factor. But the TCP domain itself could not confer the nuclear localization because the chimeric proteins with TCP domain alone were dispersed all over the transformed cells.