Occurrence, Biosynthesis, and Health Benefits of Anthocyanins in Rice and Barley.

The occurrence of anthocyanins in rice () and barley () varies among cultivars, with pigmented varieties (e.g., black rice and purple barley) accumulating higher concentrations due to genetic and environmental factors. The biosynthesis of anthocyanins is regulated by a complex network of structural and regulatory genes. Key enzymes in the pathway include chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and UDP-glucose flavonoid 3-O-glucosyltransferase (UFGT). These genes are tightly controlled by transcription factors (TFs) from the MYB, bHLH (basic helix-loop-helix), and WD40 repeat families, which form the MBW () regulatory complex. In rice, transcription factors such as , , and (Purple Leaf) interact with partners (e.g., , ) to activate anthocyanin biosynthesis. Similarly, in barley, genes (e.g., ) coordinate with TFs to regulate pigment accumulation. Environmental cues, such as light, temperature, and nutrient availability, further modulate these TFs, influencing the production of anthocyanin. Understanding the genetic and molecular mechanisms behind the biosynthesis of anthocyanins in rice and barley provides opportunities for the development of biofortification strategies that enhance their nutritional value.