Screening and functional characterization of R2R3-MYB transcription factors regulating anthocyanin biosynthesis in lotus (Nelumbo nucifera).

Abstract

Anthocyanin biosynthesis is a key process determining flower color in lotus. In this study, 145 MYB transcription factors were identified from the lotus genome, of which 124 belong to the R2R3-MYB subfamily. Based on phylogenetic analysis and short-term light-induced transcriptome data, NnMYB38 and NnMYB114 were selected for further characterization. Expression of NnMYB38 and NnMYB114 was significantly higher in red-flowered lotus, with NnMYB38 showing a positive correlation with anthocyanin content. Transient overexpression in Nicotiana benthamiana revealed that NnMYB38 induced significant anthocyanin accumulation by upregulating multiple structural genes. In transgenic Arabidopsis, both MYB TFs promoted anthocyanin accumulation in mature seeds, and the seedlings of NnMYB114-OE line exhibited red pigmentation. Dual-luciferase assays confirmed that both transcription factors significantly activated the promoters of NnDFR and NnANS, indicating their crucial regulatory roles in anthocyanin biosynthesis. In this study, we screened and identified the regulatory functions of two MYB TFs in lotus anthocyanin biosynthesis, providing new insights into the molecular mechanisms underlying lotus flower coloration.