Flavonols,
flavones, and isoflavones are flavonoids possessing broad pharmacological
activities, such as antiviral, anti-inflammatory, and antioxidant effects.
Their biosynthetic pathways have been largely elucidated. This article reviews
the regulatory patterns and mechanisms mediated by transcription factors for
these three types of flavonoids. Research on flavonol regulation involves a
wide range of species, while studies on flavone regulation have primarily
focused on species within the Lamiaceae, Rutaceae, and Asteraceae families
(e.g.,
Scutellaria baicalensis, citrus, chrysanthemum). Research on
isoflavone regulation is mainly concentrated in the Fabaceae family (e.g.,
soybean). Both positive and negative regulation exist for all three classes,
although reports on negative regulation for flavones and isoflavones are
relatively scarce. The regulatory patterns of these three flavonoid classes
differ from those of anthocyanins and exhibit common regulatory modes,
including: (1) Sole regulation by MYB transcription factors, which represents
the predominant mode; (2) Sole regulation by other transcription factors; (3)
Complex-mediated regulation (e.g., MYB forming binary/ternary complexes with
other transcription factors). Based on the types of target genes acted upon,
the regulatory mechanisms can be categorized into: multi-target regulation,
specific gene regulation (e.g., regulation of FLS for flavonols and FNS for
flavones), and regulation of glycosylation genes. Additionally, these
mechanisms include cascade regulation and competitive regulation (the latter is
primarily observed in flavonols). This review provides a reference for in-depth
analysis of the transcriptional regulatory networks governing the biosynthesis
of these three bioactive flavonoid classes, thereby facilitating related
research in synthetic biology and molecular breeding.