Multi-omics analysis of the accumulation mechanism of flavonoids in rice caryopsis under blue light.

Key message: Blue light influences the MYB gene family, resulting in varying accumulations of different flavonoids in rice caryopsis at distinct developmental stages, with a higher concentration observed in the initial stage. The regulatory effect of blue light on plant flavonoids has been extensively documented; however, its influence on the development of rice caryopsis morphology remains unreported. Through the analysis of transcriptomes, proteomes, and metabolites, combined with Weighted Gene Co-expression Network Analysis (WGCNA), the accumulation of flavonoids in rice caryopsis under blue light at various developmental stages was thoroughly examined. Furthermore, four MYB family transcription factors (TFs) that significantly influence the structural genes involved in flavonoid biosynthesis were identified. The results indicate that the accumulation of flavonoids primarily occurs during the early stages of caryopsis development. Key structural genes, including PAL, 4CL, CHS, CHI, F3H, and FLS, are upregulated in both gene and protein expression when exposed to blue light. Moreover, the WGCNA analysis identified several TFs that may influence these genes, including Os08t0144000-01 and Os01t0695900-01, as well as the proteins Q7F3D6, Q2QM89, A0A0P0W9C3, and Q6ZDM0, all of which belong to the MYB family. The research has enhanced our understanding of flavonoid accumulation in rice caryopsis when exposed to blue light. It also establishes a framework for the synthesis of secondary metabolites induced by blue light, thereby creating more opportunities to enhance the quality of horticultural plants.