NMR characterization of lignins in Arabidopsis altered in the activity of ferulate 5-hydroxylase

• Published in: Proceedings of the National Academy of Sciences - PNAS 1999-10, Vol.96 (22), p.12328-12332
• Main Authors: Marita, J.M, Ralph, J, Hatfield, R.D, Chapple, C
• Format: Article
• Language: English
• Subjects: Alcohols; Arabidopsis - chemistry; Arabidopsis - enzymology; Arabidopsis Proteins; Arabidopsis thaliana; Biochemistry; Biological Sciences; Carbon; Cauliflower mosaic virus; chemical structure; Cytochrome P-450 Enzyme System; dibenzodioxocin; enzyme activity; Ethers; F5H gene; ferulate 5-hydroxylase; Flowers & plants; gene expression; gene overexpression; Genes; Lignin; Lignin - chemistry; Magnetic Resonance Spectroscopy; Mixed Function Oxygenases - metabolism; Mutation; NMR; Nuclear magnetic resonance; nuclear magnetic resonance spectroscopy; oxygenases; phenylcoumaran; Plant Proteins - metabolism; Plants; Plants, Genetically Modified - chemistry; Plants, Genetically Modified - enzymology; Polymers; Protons; Spectral correlation; Transgenic plants
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.22.12328

Nuclear magnetic resonance (NMR) of isolated lignins from an Arabidopsis mutant deficient in ferulate 5-hydroxylase (F5H) and transgenic plants derived from the mutant by overexpressing the F5H gene has provided detailed insight into the compositional and structural differences between these lignins. Wild-type Arabidopsis has a guaiacyl-rich, syringyl-guaiacyl lignin typical of other dicots, with prominent beta-aryl ether (beta-O-4), phenylcoumaran (beta-5), resinol (beta-beta), biphenyl/dibenzodioxocin (5-5), and cinnamyl alcohol end-group structures. The lignin isolated from the F5H-deficient fah1-2 mutant contained only traces of syringyl units and consequently enhanced phenylcoumaran and dibenzodioxocin levels. In fah1-2 transgenics in which the F5H gene was overexpressed under the control of the cauliflower mosaic virus 35S promoter, a guaiacyl-rich, syringyl/guaiacyl lignin similar to the wild type was produced. In contrast, the isolated lignin from the fah1-2 transgenics in which F5H expression was driven by the cinnamate 4-hydroxylase promoter was almost entirely syringyl in nature. This simple lignin contained predominantly beta-aryl ether units, mainly with erythro-stereochemistry, with some resinol structures. No phenylcoumaran or dibenzodioxocin structures (which require guaiacyl units) were detectable. The overexpression of syringyl units in this transgenic resulted in a lignin with a higher syringyl content than that in any other plant we have seen reported.