Flavonoids are secondary metabolites in plants with diverse biological functions, including protection against biotic and abiotic stresses. They play key roles in plant interactions with other organisms, such as insects, animals, and microorganisms, and are involved in plant defense mechanisms. Flavonoids exhibit strong antioxidant properties, which help maintain cellular redox balance and protect against reactive oxygen species (ROS). They also regulate plant-microbe interactions, such as symbiosis with nitrogen-fixing bacteria and mycorrhizal fungi, by signaling pathways that promote root nodule formation and fungal colonization. Flavonoids can act as allelopathic agents, inhibiting the growth of other plants by affecting seed germination and root development. In plant pathogen resistance, flavonoids inhibit pathogen enzymes, chelate metal ions, and reduce pathogen spread by strengthening plant cell structures. Flavonoids also contribute to plant adaptation to environmental stresses, such as UV radiation, drought, and heavy metals, by scavenging ROS and modulating gene expression. They are involved in plant development through regulation of auxin transport and signaling, influencing root growth and nodule formation. Flavonoids have potential applications in agriculture, medicine, and cosmetology due to their antioxidant, anti-inflammatory, and antimicrobial properties. Their natural origin and lack of adverse effects make them promising candidates for biopesticides and functional food ingredients. Further research is needed to fully understand their roles in plant physiology and to develop practical applications in various fields.Flavonoids are secondary metabolites in plants with diverse biological functions, including protection against biotic and abiotic stresses. They play key roles in plant interactions with other organisms, such as insects, animals, and microorganisms, and are involved in plant defense mechanisms. Flavonoids exhibit strong antioxidant properties, which help maintain cellular redox balance and protect against reactive oxygen species (ROS). They also regulate plant-microbe interactions, such as symbiosis with nitrogen-fixing bacteria and mycorrhizal fungi, by signaling pathways that promote root nodule formation and fungal colonization. Flavonoids can act as allelopathic agents, inhibiting the growth of other plants by affecting seed germination and root development. In plant pathogen resistance, flavonoids inhibit pathogen enzymes, chelate metal ions, and reduce pathogen spread by strengthening plant cell structures. Flavonoids also contribute to plant adaptation to environmental stresses, such as UV radiation, drought, and heavy metals, by scavenging ROS and modulating gene expression. They are involved in plant development through regulation of auxin transport and signaling, influencing root growth and nodule formation. Flavonoids have potential applications in agriculture, medicine, and cosmetology due to their antioxidant, anti-inflammatory, and antimicrobial properties. Their natural origin and lack of adverse effects make them promising candidates for biopesticides and functional food ingredients. Further research is needed to fully understand their roles in plant physiology and to develop practical applications in various fields.