Quercetin-mediated changes in biochemical pathways to omit stress in plants

Flavonoids are a special category of hydroxylated phenolic compounds having an aromatic ring structure. Among several subclasses of flavonoids, the flavonol subclass contains a special compound – quercetin. Quercetin is a bioactive natural compound built upon the flavon structure, i.e., C6(ring A)-C3(ring C)-C6(ring B). It facilitates several plant physiological processes such as seed germination, pollen growth, antioxidant machinery, and photosynthesis, as well as induces proper plant growth and development. Quercetin is a powerful antioxidant, so it potently provides plant tolerance against several biotic and abiotic stresses. This review highlights the role of quercetin in increasing several physiological and biochemical processes in under stress and non-stress environments. Additionally, this review briefly assesses the role of quercetin in mitigating biotic and abiotic stresses, e.g., salt, heavy metal, and UV stress. Furthermore, the biosynthesis of flavonoids along with fresh advances and regulation in its signaling pathway, as well as the role of quercetin in plant signaling is also discussed.