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
 Wheat, Sorghum and Forage Research: Lincoln, NE
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Plains Area Lincoln, Nebraska Wheat, Sorghum and Forage Research 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

Title:   Author  item
                                            SABALLOS, ANA - University Of Floridaitem
                                            Sattler, Scottitem
                                            SANCHEZ, EMILIO - Washington State Universityitem
                                            FOSTER, TIM - University Of Floridaitem
                                            Xin, Zhanguoitem
                                            KANG, CHULHEE - Washington State Universityitem
                                            Pedersen, Jeffreyitem
                                            VERMERRIS, WILFRED - University Of Florida
  Submitted to: Plant Journal
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 1/27/2012
                                    Publication  Date: 4/4/2012
                                    Citation: Saballos, A., Sattler, S.E., Sanchez, E., Foster, T., Xin, Z., Kang, C., Pedersen, J.F., Vermerris, W. 2012. Sorghum Brown midrib 2 (Bmr2) gene encodes the major 4-coumarate Coenzyme A ligase involved in lignin synthesis. Plant Journal. 70:818-830.Interpretive Summary: In the US, sorghum biomass (stalks and leaves) serves as an important forage crop for livestock.  In addition, sorghum is being developed as a bioenergy crop for cellulosic bio-fuels.  Cellulosic bio-fuels are derived from the breakdown of cell wall polymers (cellulose and hemicellulose) of the biomass to sugars.  A third cell wall polymer, lignin, makes cell walls resistant to breakdown either in livestock digestive systems or in the cellulosic conversion process.  Brown midrib 2 (bmr2) is a mutant that reduces lignin content and alters lignin composition of sorghum cell walls.  In this study, we identified the mutation causing bmr2 and showed that the mutation affects an enzyme involved in lignin synthesis.  We have characterized the function of this enzyme and determined that this enzyme is largely responsible for an initial step in lignin synthesis.  The bmr2 gene represents a strategic target to improve biomass for bioenergy and forage uses in sorghum and other bioenergy grasses such as Switchgrass and Miscanthus.
                                Technical Abstract: Successful modification of plant cell wall composition without compromising plant integrity is dependent on being able to modify the expression of specific genes, but can be very challenging when the target genes are members of multigene families.  4-Coumarate:CoA ligase (4CL) catalyzes the formation of p-coumaroyl-CoA, a precursor of both flavonoids and monolignols, and has been an attractive target for transgenic down-regulation aimed at improving agro-industrial properties.  The inconsistent phenotypes of the resulting transgenics has been attributed to variable levels of down-regulation of multiple 4CL genes.  Phylogenetic analysis of the sorghum genome revealed 24 4CL(-like) proteins, five of which cluster with bona fide 4CLs from other species.  This is the first report of a 4CL mutant, which allowed us to unequivocally establish the role of an individual 4CL gene, and the implications of not having the corresponding 4CL enzyme. Analysis of two sorghum brown midrib2 (bmr2) mutants in which missense mutations result in the near absence of soluble Bmr2 protein and severe reduction in 4CL activity, showed that Bmr2 is the main 4CL involved in lignification in sorghum stems, leaves and roots, both at the seedling stage and in pre-flowering plants. In vitro enzyme assays indicated its preferred substrate is 4-coumarate.  The Bmr2 gene appears to be under auto-regulatory control based on the observation that the reduced 4CL activity results in overexpression of the defective gene, along with several other 4CL paralogs, the products of which are likely to compensate for some of the lost activity.


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