Document Detail


Structure, chemical composition, and xylanase degradation of external layers isolated from developing wheat grain.
MedLine Citation:
PMID:  15537325     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The external layers of wheat grain were investigated during maturation with respect to chemical and structural features and xylanase degradability. Cytochemical changes were observed in the isolated peripheral tissues of the wheat grain at four defined stages following anthesis. Marked chemical changes were highlighted at 11 days after anthesis, for which protein and lipid contents varied weakly. The profile of esterified ferulic acid showed large variation in the maturing peripheral layers of grain in contrast to the deposition of ferulate dimers, p-coumaric and sinapic acids. Lignin was monitored at the latest stages of ripening, which corresponds to the cessation of reserve accumulation in the grain. Arabinoxylans (AX) reached a maximum at 20 days and did not display any significant change in arabinosyl substitution proportion until ripeness. When submitted to xylanase, all outer layers were similarly altered in the proportion of soluble AX except for the peripheral tissues of the 11-day-aged wheat grain that had very little AX. Aleurone and nucellar layers were mostly degraded, whereas pericarp stayed intact at all stages of maturation. This degradation pattern was connected with the preferential immunolocalization of xylanase in aleurone and nucellar layers irrespective of the developmental stages. Further chemical examination of the enzyme-digested peripheral tissues of the grain supports the facts that ferulic ester is not a limiting factor in enzyme efficiency. Arabinose branching, ferulic dimers, and ether-linked monomers that are deposited early in the external layers would have more relevance to the in situ degradability of AX.
Authors:
Johnny Beaugrand; David Crônier; Pascal Thiebeau; Lucas Schreiber; Philippe Debeire; Brigitte Chabbert
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of agricultural and food chemistry     Volume:  52     ISSN:  0021-8561     ISO Abbreviation:  J. Agric. Food Chem.     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-11-11     Completed Date:  2004-12-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0374755     Medline TA:  J Agric Food Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7108-17     Citation Subset:  IM    
Affiliation:
Equipe Parois Végétales et Matériaux Fibreux, UMR FARE-614, Institut National de la Recherche Agronomique, 2 Esplanade Roland Garros, 51686 Reims 02, France.
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MeSH Terms
Descriptor/Qualifier:
Carbohydrates / analysis
Endo-1,4-beta Xylanases / metabolism*
Lipids / analysis
Phenols / analysis
Plant Proteins / analysis
Seeds / chemistry*,  growth & development*
Triticum / chemistry*,  growth & development*
Xylans / analysis
Chemical
Reg. No./Substance:
0/Carbohydrates; 0/Lipids; 0/Phenols; 0/Plant Proteins; 0/Xylans; 9040-27-1/arabinoxylan; EC 3.2.1.8/Endo-1,4-beta Xylanases

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