Identification and characterization of 13 gene families encoding enzymes involved in flavonoid biosynthesis in barley and their roles under abiotic stress.

Flavonoids are polyphenolic secondary metabolites, which potentially involved in growth, development, reproduction, and stress tolerance in plants. Barley is a monocot crop that contains antioxidant flavonoids. Hence, we have identified and characterized 108 flavonoid biosynthesis enzymes in barley. Distribution of all 108 enzymes into five major superfamilies, following 13 subfamilies during phylogenetic analysis may reveal their evolutionary origin. The existence of light, hormone, and stress-responsive components in the enzymes potentially linked to their vital role in hormonal balance and stress tolerance. The highest binding affinity (−8.3 kcal/mol) in HvANS1–flavone, HvANS1–baicalein, and HvCHI3–glabranine docked complexes indicate a strong enzyme–substrate interaction, which support their potential functional relevance in flavonoid biosynthesis. Molecular dynamics simulation supported docking findings, revealing stable and functional complexes. Significant upregulation of HvCHS1 in the root and downregulation of HvF3’H20 in the same tissue under high temperature stress, along with downregulation of HvCHI2 in the root under salinity and HvDFR13 in the stem under salinity and drought stress, might represent their differential responses to specific abiotic stress. Plasma membrane and nuclear-localized HvCHS1 protein may regulate transport and homeostasis of cytosolic flavonoids. The precise characterization of flavonoid biosynthesis enzymes may guide plant biologists in developing barley with improved biosynthesis, transport, homeostasis of flavonoids, and abiotic stress tolerance.