Effects of methyl jasmonate and salicylhydroxamic acid on the biosynthesis of flavonoids in Glycyrrhiza glabra L. hairy roots

• MeJA increases flavonoids; SHAM decreases them, highlighting jasmonates' role. • MeJA upregulates genes and flavonoids; SHAM does the opposite. • MeJA activates MYB/bHLH TFs like GurMYB04 ; SHAM suppresses them. • GurMYB04 is a key regulator for flavonoid production. • Jasmonates promote and inhibit flavonoids, showing complex regulation. Glycyrrhiza glabra L., a commercially important licorices species, is rich in flavonoids with significant medicinal properties. Phytohormone jasmonates play a pivotal role in modulating flavonoid biosynthesis, though their specific impact on distinct flavonoid subclasses in G. glabra remains unclear. This study investigates the effects of methyl jasmonate (MeJA) and salicylhydroxamic acid (SHAM) on flavonoid biosynthesis in G.glabra hairy roots using transcriptomic and metabolomic analyses. MeJA treatment significantly upregulated key enzymes and transcription factors involved in flavonoid biosynthesis, leading to increased levels of specific flavonoids such as 8-prenylnaringenin. Conversely, SHAM treatment downregulated these genes and reduced flavonoid content. Notably, GurMYB04 emerged as a key regulator of flavonoid biosynthesis, showing contrasting expression patterns under MeJA and SHAM treatments. These findings highlight the divergent role of jasmonate signaling in flavonoid biosynthesis and provide insights for targeted metabolic engineering in G. glabra .