BACKGROUND: The objective of this study was to reveal the flavonoid biosynthesis pathway in white (Z6), red (Z27) and black (HC4) seeds of the sweet sorghum (Sorghum bicolor) using metabolomics and transcriptomics, to identify different flavonoid metabolites, and to analyze the differentially expressed genes involved in flavonoid biosynthesis.RESULTS: We analyzed the metabolomics and transcriptomics data of sweet sorghum seeds. Six hundred and fifty-one metabolites including 171 flavonoids were identified in three samples. Integrated analysis of transcriptomics and metabolomics showed that 8 chalcone synthase genes (gene19114, gene19115, gene19116, gene19117, gene19118, gene19120, gene19122 and gene19123) involved in flavonoid biosynthesis, were identified and play central role in change of color. Six flavanone including homoeriodictyol, naringin, prunin, naringenin, hesperetin and pinocembrin were main reason for the color difference.CONCLUSIONS: Our results provide valuable information on the flavonoid metabolites and the candidate genes involved in the flavonoid biosynthesis pathway in sweet sorghum seeds.

Inner Mongolia Autonomous Region College Youth Science and Technology Talent Project NJYT22052

Inner Mongolia Autonomous Region Science and Technology Plan 2020GG0102

Inner Mongolia Science and Technology Innovation Guide Project KJCX1702

National Ethnic Affairs Commission Higher Education Teaching Reform Research Project - Research Project on Germplasm Identification of Salt-Alkali-tolerant High-quality Sorghum in West Liaohe Plain 21087

Natural Science Foundation of Inner Mongolia Autonomous Region 2019MS03076

Project of the Education Department of Inner Mongolia Autonomous Region NJZY17193

Research Project of Inner Mongolia Minzu University BS621

Research Project of Inner Mongolia Minzu University NMDYB18036