Open AccessLignin monomer composition is determined by the expression of a cytochrome P450-dependent monooxygenase in Arabidopsis
Author(s) -
Knut Meyer,
Amber M. Shirley,
Joanne C. Cusumano,
Dolly A. Bell-Lelong,
Clint Chapple
Publication year - 1998
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.95.12.6619
Subject(s) - lignin , arabidopsis , ferulic acid , phenylpropanoid , biochemistry , mutant , chemistry , monomer , hydroxylation , biosynthesis , composition (language) , cell wall , biology , enzyme , gene , organic chemistry , linguistics , philosophy , polymer
The phenylpropanoid pathway provides precursors for the biosynthesis of soluble secondary metabolites and lignin in plants. Ferulate-5-hydroxylase (F5H) catalyzes an irreversible hydroxylation step in this pathway that diverts ferulic acid away from guaiacyl lignin biosynthesis and toward sinapic acid and syringyl lignin. This fact led us to postulate that F5H was a potential regulatory step in the determination of lignin monomer composition. To test this hypothesis, we have usedArabidopsis to examine the impact of F5H overexpression.Arabidopsis is a useful model system in which to study lignification because in wild-type plants, guaiacyl and syringyl lignins are deposited in a tissue-specific fashion, while the F5H-deficientfah1 mutant accumulates only guaiacyl lignin. Here we show that ectopic overexpression of F5H inArabidopsis abolishes tissue-specific lignin monomer accumulation. Surprisingly, overexpression of F5H under the control of the lignification-associated cinnamate-4-hydroxylase promoter, but not the commonly employed cauliflower mosaic virus 35S promoter, generates a lignin that is almost entirely comprised of syringylpropane units. These experiments demonstrate that modification of F5H expression may enable engineering of lignin monomer composition in agronomically important plant species.