U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 U.S. Dairy Forage Research Center: Madison, WI
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    Careers


        


                    Archives
                        Presentations
                                    World Dairy Expo
                                    Newsletters and Research Summaries
                    Resources
                        General Resources
                                    Books
                                    Teacher's Resources
                                    New Research Dairy Updates
                                    Integrated Research at USDFRCSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area Madison, Wisconsin U.S. Dairy Forage Research Center Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications
- IACUC Summaries - Milwaukee, WI Aquaculture
- IACUC Summaries - US Dairy Forage Research Center

Title:   Author  item
                                            Grabber, Johnitem
                                            Ralph, Johnitem
                                            LAPIERRE, CAHTERINE - INRA-FRANCEitem
                                            BARRIERE, YVES - INRA-FRANCE
  Submitted to: Journal of the French Academy of Science
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 4/20/2004
                                    Publication  Date: 5/1/2004
                                    Citation: Grabber, J.H., Ralph, J., Lapierre, C., Barriere, Y. 2004. Genetic and molecular basis of grass cell wall biosynthesis and degradability i.  lignin-cell wall matrix interactions. Journal of the French Academy of Science. v. 327. p. 455-465.Interpretive Summary: Forage grasses are a major feedstuffs for livestock and grass cereal crops like maize, rice, wheat, oats and rye supply most of the dietary energy needs of people and many types of livestock. Fiber makes up 25 to 80% of the dry weight of grasses and it is composed primarily of complex carbohydrates.  These carbohydrates are potentially an important source of digestible energy for livestock and they may also be converted into various chemicals for use in automobile fuels, plastics, and other products. Unfortunately, the enzymatic breakdown of complex carbohydrates into sugars is limited by an indigestible component in fiber known as 'lignin'. In the 1st part of this paper, we review how the formation and chemical makeup of lignins and their attachment to structural polysaccharides influences the enzymatic degradability of fiber. This review will help scientists to develop improved grasses and processing methods so that lignin is less of a barrier to fiber digestion. Ultimately these studies will lower the cost and environmental impact of converting grasses and cereal crop residues into food, fuel, and industrial products.
                                Technical Abstract: Lignification of cell walls is a major factor limiting the degradability of grasses in the rumen or large intestine of herbivores. Monolignols transported from the cytosol to the apoplast undergo oxidase-mediated polymerization to form lignins composed mainly of guaiacyl (G) and syringyl (S) units with lesser amounts of p-hydroxyphenyl (H) units. Lignification is a spatially and temporally regulated phenomenon, and lignin composition and structure differs between primary and secondary cell walls and among tissues types.  Grass lignins are cross-linked to the cell wall matrix by oxidative coupling of monolignols to ferulate and diferulate xylan esters and possibly by nucelophilic addition of structural sugars and amino acids to lignin quinone-methide intermediates. In some cases, cross-linking between lignin polymers is probably mediated by photocatalyzed cyclodimers of p-coumarate esters on syringyl units.  Variations in lignin deposition, cross-linking and, in some cases, composition influence the enzymatic degradability of grass cell walls.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov