Objective To screen and identify members of the bHLH transcription factor family based on genomic data from Forsythia suspensa and characterize their features and functions. Methods Using the genomic data of F. suspensa, the bHLH transcription factor family was screened and identified, analysing their physicochemical properties and phylogenetic relationships, and characterizing the bHLH genes by analysing their chromosomal locations, gene structures, functional annotations, and cis-acting elements. In addition, F. suspensa leaves were treated with exogenous methyl jasmonate (MeJA) and expression pattern of FsbHLHs within 48 h after treatment was detected by qRT-PCR. Correlation analysis was conducted in combination with the changes in phillygenin content. Results A total of 170 bHLH transcription factors with complete HLH conserved domains were identified, and these factors were distributed across 14 chromosomes. Their amino acid lengths ranged from 67 to 885 aa, relative molecular masses from 7 910.58 to 98 854.78, and theoretical isoelectric points (pI) from 4.71 to 10.44. Based on phylogenetic analysis, FsbHLHs were grouped into 13 subfamilies, with subfamily III being the largest. Through cis-acting element analysis, it was found that FsbHLHs contained multiple elements associated with light regulation, hormone response, and stress response. Subsequently, the correlation between MeJA-induced expression of eight FsbHLH genes and phillygenin content was analysed, and these results suggested that FsbHLH26 and FsbHLH139 were potentially critical regulators of phillygenin biosynthesis and accumulation. Conclusion This study identified 170 members of the FsbHLH gene family. Through systematic bioinformatics analysis and gene expression pattern analysis following MeJA treatment, FsbHLH26 and FsbHLH139 may be the key transcription factors involved in the biosynthesis of phillygenin, laying the foundation for future research into the molecular mechanisms underlying phillygenin biosynthesis.

Forsythia suspensa(Thunb.) Vahl  /  bHLH transcription factors  /  phillygenin  /  bioinformatics analysis  /  hormone treatment