Abstract:

The bHLH （basic helix-loop-helix） transcription factor family not only participates in plant growth and development， but also plays a key role in plant response to stress and secondary metabolism. In this study， we identified and analyzed at the whole genome level， the bHLH transcription factor family of Cenchrus purpureus （also called elephant grass， an important forage grass and energy plant）. We also analyzed the response of bHLH transcription factors to gibberellin （GA₃） and paclobutrazol （PAC） by using transcriptome data and quantitative RT-PCR. A total of 229 bHLH gene family members （CpbHLH001-CpbHLH229）， with complete conserved domains， and unevenly distributed on the 14 chromosomes， were identified. The results of phylogenetic analysis revealed that 229 CpbHLHs could be classified into 18 subgroups， of which a subgroup designated C contained the highest number （41）. The members of each subfamily had similar gene structures and conserved motifs. Expression profile analysis based on transcriptome data found that most bHLH genes responded to GA₃ and PAC in the meristems of the shoot apex， and nine genes with higher expression were randomly selected and further verified by qRT-PCR. It was found that these nine genes were differentially expressed in response to different exogenous GA₃ and PAC treatments， suggesting that these genes are associated with GA₃ and PAC mediated signaling pathways. This study lays the foundation for further research on the biological functions of the bHLH transcription factor family in elephant grass.

Key words: elephant grass, bHLHtranscription factor, gene identification, gene expression pattern