Transcriptome and metabolome reveal redirection of flavonoids in a white testa peanut mutant

Abstract Background: Coat color determines both appearance and nutrient quality of peanut. White seed coat in peanut can enhance the processing efficiency and quality of peanut oil.An integrative analysis of transcriptomes, metabolomes and histocytology was performed on a white seed coat peanut mutant (wsc) and its wild type to investigate the regulatory mechanisms underlying color pigmentation. Result：Metabolomes revealed flavonoids were redirected in wsc, while multi-omics analyses of wsc mutant seeds and testae uncovered WSC influenced the flavonoids biosynthesis in testa as well as suberin formation, glycolysis, the tricarboxylic acid (TCA) cycle and amino acid metabolism. The mutation also enhanced brassinosteroid (BR), gibberellin (GA), and jasmonic acid (JA) biosynthesis as well as abscisic acid (ABA), auxin (AUX), BR and JA signaling. Further, co-expression analysis showed that flavonol synthase (FLS) genes co-expressed with MYB-bHLH-WD40 (MBW) complex member genes. Combining tissue expression patterns, genetic analyses, and the annotation of common differentially expressed genes (DEGs) for these three stages revealed that three testa specific expressed candidate genes, Araip.M7RY3, Aradu.R8PMF and Araip.MHR6K were likely responsible for the white testa phenotype. WSC might be regulated expression competition between FLS and dihydroflavonol 4-reductase (DRF) by controlling hormone synthesis and signaling as well as the MBW complex. Conclusions: The results of this study therefore provide both candidate genes and novel approaches that can be applied to improve peanut with desirable seed coat color and flavonoid quality.