Tricin Biosynthesis and Bioengineering

Abstract

Tricin (3',5'-dimethoxyflavone) is a specialized metabolite which not only confers stress tolerance and involves in defense responses in plants but also represents a promising nutraceutical. Tricin-type metabolites are widely present as soluble tricin O-glycosides and tricin-oligolignols in all grass species examined, but only show patchy occurrences in unrelated lineages in dicots. More strikingly, tricin is a lignin monomer in grasses and several other angiosperm species, representing one of the “non-monolignol” lignin monomers identified in nature. The unique biological functions of tricin especially as a lignin monomer have driven the identification and characterization of tricin biosynthetic enzymes in the past decade. This review summarizes the current understanding of tricin biosynthetic pathway in grasses and tricin-accumulating dicots. The characterized and potential enzymes involved in tricin biosynthesis are highlighted along with discussion on the debatable and uncharacterized steps. Finally, current developments of bioengineering on manipulating tricin biosynthesis toward the generation of functional food as well as modifications of lignin for improving biorefinery applications are summarized.

Modulation of lignin biosynthesis for drought tolerance in plants

“…Through these sequential enzymatic reactions, cinnamic acid is converted into three phenolic precursors ( Fraser and Chapple, 2011 ; Xie et al., 2018 ) ( Figure 1 ). In addition to these three general precursors of lignin, C, 5H, tricin, and coumaroylated G/S monomers are also synthesized in plants ( Petrik et al., 2014 ; Zhao, 2016 ; Lam et al., 2021 ).…”

Integrative analysis of metabolite and transcriptome reveals biosynthetic pathway and candidate genes for eupatilin and jaceosidin biosynthesis in Artemisia argyi

“…We propose an alternative biosynthetic route that utilizes chrysoeriol and batatifolin as intermediates ( Figure 3C ) and excludes biochemically unfavorable reactions. Supporting this proposed pathway, luteolin has been found to be an active substrate for F3´OMT producing chrysoeriol in rice during the biosynthesis of another polymethoxy flavone, tricin ( Lam et al., 2021 ). For the production of eupatilin and jaceosidin, 6- O -methylation catalyzed by F6OMT or bifunctional F6/4´OMT is also indispensable.…”

Integrated metabolomic and transcriptomic analysis revealed the flavonoid biosynthesis and regulation in Areca catechu

“…Flavonoids widely exist in the plant kingdom 8 . Flavonoids have a basic diphenylpropane backbone (C6–C3–C6) consisting of two benzene rings (A‐ring and B‐ring) and a middle pyrone ring (C‐ring) 9 . According to the different C‐ring structures, flavonoids can be divided into eight categories including chalcones, isoflavones, and flavonols 10 .…”

“…8 Flavonoids have a basic diphenylpropane backbone (C6-C3-C6) consisting of two benzene rings (A-ring and B-ring) and a middle pyrone ring (C-ring). 9 According to the different C-ring structures, flavonoids can be divided into eight categories including chalcones, isoflavones, and flavonols. 10 Flavonoids have many vital functions during the growth and development of plants, including auxin transport, flower colouring, and ultraviolet (UV) protection.…”