VrNAC25 Promotes Anthocyanin Synthesis in Mung Bean Sprouts Synergistically with VrMYB90

Anthocyanins pigment plant tissues, mitigate biotic and abiotic stresses, and deliver human health benefits; raising their content in mung bean (Vigna radiata) sprouts is a long-standing research target. Transcriptome analysis identified VrNAC25, a NAC transcription factor whose expression closely parallels anthocyanin accumulation; functional validation in mung bean confirmed that VrNAC25 acts as a positive regulator of the pathway. Although VrNAC25 does not bind to the promoters of the key structural genes VrDFR or VrLDOX, it indirectly controls anthocyanin synthesis by interacting with the core R2R3-MYB activator VrMYB90, previously established as the central regulator of anthocyanin production in mung beans. This interaction operates at both transcriptional and protein levels, thereby amplifying the expression of downstream structural genes and boosting pigment accumulation. Our findings refine the molecular network governing anthocyanin biosynthesis in sprouts and provide a clear theoretical basis for breeding or biotechnological strategies aimed at enhancing the nutritional quality and commercial value of mung bean products through light treatment or by selecting an anthocyanin-rich mung bean variety.