Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2007-3-28
pubmed:databankReference
pubmed:abstractText
Mutations of Arabidopsis thaliana IRREGULAR XYLEM8 (IRX8) and IRX9 were previously shown to cause a collapsed xylem phenotype and decreases in xylose and cellulose in cell walls. In this study, we characterized IRX8 and IRX9 and performed chemical and structural analyses of glucuronoxylan (GX) from irx8 and irx9 plants. IRX8 and IRX9 are expressed specifically in cells undergoing secondary wall thickening, and their encoded proteins are targeted to the Golgi, where GX is synthesized. 1H-NMR spectroscopy showed that the reducing end of Arabidopsis GX contains the glycosyl sequence 4-beta-D-Xylp-(1-->4)-beta-D-Xylp-(1-->3)-alpha-L-Rhap-(1-->2)-alpha-D-GalpA-(1-->4)-D-Xylp, which was previously identified in birch (Betula verrucosa) and spruce (Picea abies) GX. This indicates that the reducing end structure of GXs is evolutionarily conserved in woody and herbaceous plants. This sequence is more abundant in irx9 GX than in the wild type, whereas irx8 and fragile fiber8 (fra8) plants are nearly devoid of it. The number of GX chains increased and the GX chain length decreased in irx9 plants. Conversely, the number of GX chains decreased and the chain length heterodispersity increased in irx8 and fra8 plants. Our results suggest that IRX9 is required for normal GX elongation and indicate roles for IRX8 and FRA8 in the synthesis of the glycosyl sequence at the GX reducing end.
pubmed:commentsCorrections
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pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
1040-4651
pubmed:author
pubmed:issnType
Print
pubmed:volume
19
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
549-63
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Arabidopsis irregular xylem8 and irregular xylem9: implications for the complexity of glucuronoxylan biosynthesis.
pubmed:affiliation
Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.