Comprehensive genome-wide analysis of bHLH family genes in Nymphaea colorata and molecular characterization of NcTT8.

Background: Water lilies (Nymphaea spp.) are important aquatic ornamental plants with significant research value in horticulture, ecosystem studies, and evolutionary biology. The basic helix-loop-helix (bHLH) transcription factors, one of the largest transcription factor families in plants, play pivotal roles in regulating plant growth and development, secondary metabolism, and stress responses.

Results: A total of 76 bHLH genes, including 5 MYC genes, were identified in N. colorata. Among these, 18 genes underwent segmental duplication, while five genes experienced tandem duplication. Natural selection was identified as the primary driver of codon usage bias in NcbHLH genes. Promoter analysis revealed multiple cis-acting elements associated with hormone responses and abiotic stress responses. Functional annotation suggested that several NcbHLH transcription factors may be involved in floral organ development, stress responses, and the jasmonic acid (JA) signaling pathway. Notably, NcMYC3, a homolog of TT8, was localized to the nucleus and demonstrated transcriptional activation activity.

Conclusions: This study systematically elucidates the evolutionary characteristics and functional properties of the N. colorata bHLH gene family, providing a foundation for further exploration of the regulatory mechanisms of bHLH transcription factors and their roles in anthocyanin biosynthesis.