Cross-coupling of hydroxycinnamyl aldehydes into lignins.
Pathways for hydroxycinnamyl aldehyde incorporation into lignins are revealed by examining transgenic plants deficient in cinnamyl alcohol dehydrogenase, the enzyme that converts hydroxycinnamyl aldehydes to the hydroxycinnamyl alcohol lignin monomers. In such plants the aldehydes incorporate into lignins via radical coupling reactions. As diagnostically revealed by long-range (13)C-(1)H correlative NMR, sinapyl aldehyde (3, 5-dimethoxy-4-hydroxy-cinnamaldehyde) 8-O-4-cross-couples with both guaiacyl (3-methoxy-4-hydroxyphenyl-propanoid) and syringyl (3, 5-dimethoxy-4-hydroxyphenyl-propanoid) units, whereas coniferyl aldehyde cross-couples only with syringyl units.
U.S. Dairy Forage Research Center, USDA-Agricultural Research Service, Madison, Wisconsin 53706, USA.
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Kim
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Ralph
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Yahiaoui
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Pean
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Boudet
D000429:Alcohol Oxidoreductases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism; D002934:Cinnamates / Q000737:chemistry / Q000378:metabolism*; D006139:Guaiacol / Q000031:analogs & derivatives / Q000378:metabolism; D008031:Lignin / Q000096:biosynthesis* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism
D000447:Aldehydes; D002934:Cinnamates; C117045:p-hydroxycinnamaldehyde; D006139:Guaiacol; D008031:Lignin; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase