The Characterization of R2R3-MYB Genes in Water Lily Nymphaea colorata Reveals the Involvement of NcMYB25 in Regulating Anthocyanin Synthesis

Abstract

Nymphaea colorata, valued for its diverse flower colors and attractive shapes, is a popular ornamental aquatic plant. Anthocyanins provide color to flowers, and their biosynthesis is regulated by the R2R3-MYB transcription factor. In this study, we identified and analyzed the R2R3-MYB genes in N. colorata, focusing on their structure, evolution, expression patterns, regulatory mechanisms, and biological functions. We also investigated the role of the NcMYB25 gene in anthocyanin biosynthesis. There were 59 R2R3-MYB genes in N. colorata, distributed across 14 chromosomes. Among these, 14 genes were involved in segmental duplications and 6 in tandem duplications. Multiple R2R3-MYB transcription factors appeared to play a role in biological processes in N. colorata, including NcMYB48 in flavonoid synthesis, NcMYB33 in lignin synthesis, NcMYB23 in cold stress response, and NcMYB54 in osmotic stress response. Additionally, we identified 92 miRNAs in N. colorata, with 43 interacting with 35 R2R3-MYB genes. The NcMYB25 protein is localized in the nucleus and possesses transcriptional activation activity. Overexpression of the NcMYB25 gene in an apple pericarp resulted in anthocyanin accumulation. These findings provide insight into the evolutionary trajectory of the R2R3-MYB genes in N. colorata and highlight the regulatory function of the NcMYB25 gene in anthocyanin biosynthesis.