Abstract
Phenolic compounds are derived from the phenylpropanoid metabolic pathways of plants and include phenylpropionic acids, lignins, coumarins, and flavonoids. These compounds are among the most abundant and diverse classes of secondary metabolites found throughout the plant kingdom. Phenolic compounds play critical roles in the growth, development, and stress resistance of horticultural plants. Moreover, some phenolic compounds exhibit substantial biological activities, and they are widely utilized across various sectors, such as the pharmaceutical and food industries. The cytochrome P450 monooxygenase 98A subfamily (CYP98A) is involved mainly in the biosynthesis of phenolic compounds, mediating the meta-hydroxylation of aromatic rings in the common phenylpropane biosynthesis pathways of phenolic compounds. However, research on this family of oxidases is currently fragmented, and a systematic and comprehensive review has not yet been conducted. This review offers an exhaustive summary of the molecular features of the CYP98A family and the functions of CYP98A monooxygenases in the biosynthesis of different types of phenolic compounds. In addition, this study provides a reference for the exploration and functional study of plant CYP98A family enzymes. An enhanced understanding of CYP98A monooxygenases can help in the cultivation of high-quality horticultural plants with increased resistance to biotic and abiotic stresses and enhanced accumulation of natural bioactive compounds via metabolic engineering strategies. Moreover, the structural optimization and modification of CYP98A monooxygenases can provide additional potential targets for synthetic biology, enabling the efficient in vitro production of important phenolic compounds to address production supply conflicts.