Combined transcriptome and metabolome analyses reveal the mechanism of abundant bioactive compounds and high antioxidant activity in germinated weedy rice.

Germinated brown rice has recently garnered widespread attention due to its high nutritional value. Previous research demonstrated that the bioactive components and functional properties of germinated brown rice varieties exhibit significant differences. Three germinated rice cultivars weedy rice WR04-6 (WR) and two cultivated rice cultivars with superior eating quality, Koshihikari (YG) and Daohuaxiang (DHX), were analyzed using metabolites and transcriptome profiling. Widely targeted metabolomics results showed that 85.9% and 71.2% of differential metabolites for WR vs. YG and WR vs. DHX were enriched in WR, respectively. The substances mainly included amino acids and derivatives, carbohydrates and its derivatives, organic acids and its derivatives, and flavonoids. Higher antioxidant activity was detected in WR compared to cultivated rice in metabolome analysis. Transcriptome analyses indicated that 18 responsive genes played pivotal roles in the conversion of key metabolites. These findings will provide theoretical underpinnings for the development of rice germplasm resources and the formulation of functional germinated grain foods.