Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
47
pubmed:dateCreated
2001-1-8
pubmed:abstractText
Caffeoyl-coenzyme A O-methyltransferase (CCoAOMT) methylates, in vitro, caffeoyl-CoA and 5-hydroxyferuloyl-CoA, two possible precursors in monolignol biosynthesis in vivo. To clarify the in vivo role of CCoAOMT in lignin biosynthesis, transgenic poplars with 10% residual CCoAOMT protein levels in the stem xylem were generated. Upon analysis of the xylem, the affected transgenic lines had a 12% reduced Klason lignin content, an 11% increased syringyl/guaiacyl ratio in the noncondensed lignin fraction, and an increase in lignin-attached p-hydroxybenzoate but otherwise a lignin composition similar to that of wild type. Stem xylem of the CCoAOMT-down-regulated lines had a pink-red coloration, which coincided with an enhanced fluorescence of mature vessel cell walls. The reduced production of CCoAOMT caused an accumulation of O(3)-beta-d-glucopyranosyl-caffeic acid, O(4)-beta-d-glucopyranosyl-vanillic acid, and O(4)-beta-d-glucopyranosyl-sinapic acid (GSA), as authenticated by (1)H NMR. Feeding experiments showed that O(3)-beta-d-glucopyranosyl-caffeic acid and GSA are storage or detoxification products of caffeic and sinapic acid, respectively. The observation that down-regulation of CCoAOMT decreases lignin amount whereas GSA accumulates to 10% of soluble phenolics indicates that endogenously produced sinapic acid is not a major precursor in syringyl lignin biosynthesis. Our in vivo results support the recently obtained in vitro enzymatic data that suggest that the route from caffeic acid to sinapic acid is not used for lignin biosynthesis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/4-O-beta-glucopyranosyl caffeic acid, http://linkedlifedata.com/resource/pubmed/chemical/5-hydroxyferuloyl-coenzyme A, http://linkedlifedata.com/resource/pubmed/chemical/Acyl Coenzyme A, http://linkedlifedata.com/resource/pubmed/chemical/Caffeic Acids, http://linkedlifedata.com/resource/pubmed/chemical/Coumaric Acids, http://linkedlifedata.com/resource/pubmed/chemical/Glucosides, http://linkedlifedata.com/resource/pubmed/chemical/Lignin, http://linkedlifedata.com/resource/pubmed/chemical/Methyltransferases, http://linkedlifedata.com/resource/pubmed/chemical/Phenols, http://linkedlifedata.com/resource/pubmed/chemical/Plant Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Vanillic Acid, http://linkedlifedata.com/resource/pubmed/chemical/caffeoyl-CoA O-methyltransferase, http://linkedlifedata.com/resource/pubmed/chemical/caffeoyl-coenzyme A, http://linkedlifedata.com/resource/pubmed/chemical/sinapinic acid
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
24
pubmed:volume
275
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
36899-909
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Modifications in lignin and accumulation of phenolic glucosides in poplar xylem upon down-regulation of caffeoyl-coenzyme A O-methyltransferase, an enzyme involved in lignin biosynthesis.
pubmed:affiliation
Vakgroep Moleculaire Genetica & Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, B-9000 Gent, Belgium.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't