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
 Cell Wall Biology and Utilization Research: Madison, WI
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area Madison, Wisconsin U.S. Dairy Forage Research Center Cell Wall Biology and Utilization 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
                                            Sullivan, Michael
  Submitted to: Meeting Abstract
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 6/16/2009
                                    Publication  Date: 7/12/2009
                                    Citation: Sullivan, M.L. 2010. Hydroxycinnamoyl-CoA:Malate Hydroxycinnamoyl Transferase is Crucial for 2-O-Caffeoyl-L-Malate Biosynthesis in Red Clover and Defines a New Pathway for Hydroxycinnamoyl-Malate Ester Biosynthesis [abstract]. Gordon Research Conference on Plant Metabolic Engineering, July 12-17, 2009, Waterville Valley, New Hampshire.Interpretive Summary:
                                Technical Abstract: Red clover (Trifolium pratense L.) leaves accumulate several μmol of phaselic acid [2-O-caffeoyl-L-malate] per gram fresh weight. Post-harvest oxidation of such o-diphenols to o-quinones by endogenous polyphenol oxidases prevents breakdown of forage protein during storage. Forages like alfalfa (Medicago sativa L.) lack both polyphenol oxidase and o-diphenols. Consequently, breakdown of their protein upon harvest and storage results in economic losses and release of excess nitrogen into the environment. Understanding how red clover synthesizes o-diphenols such as phaselic acid will help in the development of forages utilizing this natural system of protein protection. In arabidopsis (and presumably other members of the Brassicaceae), hydroxycinnamoyl-malate esters are synthesized via the action of sinapoylglucose:malate sinapoyl transferase, the product of the SNG1 gene. There is no genetic evidence for a SNG1 homolog in red clover; however, we have identified a novel hydroxycinnamoyl-CoA:malate hydroxycinnamoyl transferase (HCT2) in red clover. In vitro, HCT2 is capable of transferring p-coumaroyl, caffeoyl, and feruloyl moieties from the corresponding CoA thiolesters to a malic acid acceptor to form the corresponding 2-O-esters. Leaves of red clover plants down-regulated for HCT2 expression via hairpin RNAi have dramatically reduced levels of phaselic acid compared to leaves of untransformed control plants. Transgenic alfalfa plants expressing red clover HCT2 accumulate p-coumaroyl- and feruloyl-malate, but not the caffeoyl ester. Together these results indicate HCT2 plays a crucial role in phaselic acid biosynthesis in red clover and defines a new pathway for hydroxycinnamoyl-malate ester biosynthesis in plants. Preliminary analyses of CYP98A44, a red clover p-coumarate 3-hydroxylase (C3H), indicate it is not capable of hydroxylating p-coumaroyl-malate, suggesting that in red clover phaselic acid is formed by transfer of a caffeoyl moiety to malic acid by HCT2 and/or that a second C3H exists in red clover that is capable of hydroxylating p-coumaroyl-malate.


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