Germination-Driven Modulation of Phenolic Compounds in Sorghum: Bioactivity and Gene Expression

Controlled germination has emerged as an effective and sustainable bioprocess to enhance the nutritional and functional quality of cereal grains, including sorghum, a climate-resilient crop widely cultivated in tropical and semi-arid regions. Germination triggers coordinated physiological and molecular responses that activate secondary metabolism, particularly the phenylpropanoid pathway, resulting in qualitative and quantitative changes in phenolic compounds. This review summarizes current evidence on germination-driven modulation of sorghum phenolics, with emphasis on bioactivity and genetic regulation. Germination promotes the transcriptional activation of key biosynthetic genes, including those encoding phenylalanine ammonia-lyase and flavonoid pathway enzymes, while regulatory genes associated with condensed tannin biosynthesis, such as Tannin1 (Tan1) and Tannin2 (Tan2), may undergo functional modulation during sprouting, contributing to reduced antinutritional tannin levels. Gene expression and metabolic outcomes are strongly influenced by environmental factors such as soaking duration, temperature, oxygen availability, and elicitation conditions. The resulting phenolic profile exhibits enhanced antioxidant capacity and health-promoting potential. In sorghum-based systems, germination represents a promising strategy to increase bioactive density, reduce antinutritional constraints, and add value to grains. Improved understanding of gene-metabolite interactions during germination may support targeted breeding and the development of functional foods with improved nutritional performance.