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
 Plant Science Research: St. Paul, MN
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area St. Paul, Minnesota Plant Science 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
                                            Gronwald, Johnitem
                                            Yang, Sukitem
                                            Bucciarelli, Brunaitem
                                            Miller, Susanitem
                                            O`Rourke, Jamieitem
                                            SHIN, SANGHYUM - University Of Minnesotaitem
                                            Samac, Deborah

                                                         - *Debby*item
                                            VANCE, CARROLL - Retired ARS Employee
  Submitted to: Plant Biology Annual Meeting
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 5/30/2014
                                    Publication  Date: 7/12/2014
                                    Citation: Gronwald, J.W., Yang, S.H., Bucciarelli, B., Miller, S.S., O'Rourke, J.A., Shin, S., Samac, D.A., Vance, C.P. 2014. Transgene silencing of sucrose synthase in alfalfa stem vascular tissue by a truncated phosphoenolpyruvate carboxylase: sucrose synthase construct. Plant Biology. July 12-16, 2014. Portland, OR.Interpretive Summary:
                                Technical Abstract: An important role of sucrose synthase (SUS, EC 2.4.1.13) in plants is to provide UDP-glucose needed for cellulose synthesis in cell walls. We examined if over-expressing SUS in alfalfa (Medicago sativa L.) would increase cellulose content of stem cell walls. Alfalfa plants were transformed with two constructs: a truncated alfalfa phosphoenolpyruvate carboxylase promoter (PEPC-4) fused to ß-glucuronidase (GUS), and PEPC-4 fused with alfalfa nodule-enhanced SUS cDNA (MsSUS1). GUS histochemical staining in stems of transformants indicated that the PEPC-4 promoter was active in phloem and xylem. In contrast to what was expected, SUS transcript levels measured in stems of transformants were reduced by 75-90%. Two control transformants (M22, M35) containing the PEPC-4::GUS construct and two PEPC-4::SUS transformants (M17, M18) that exhibited 85-90% reduction of MsSUS1 transcript in ES (elongating stem) and PES (post-elongating stem) internodes were selected for further study. Immunoblotting proteins in the soluble fraction (16,000g supernatant) from stems of controls with a polyclonal antibody from maize indicated the presence of three SUS polypeptides in ES internodes and one SUS polypeptide in PES internodes. The major SUS polypeptide was absent from both ES and PES internodes in the SUS down-regulated transformants. Staining for in situ SUS activity in stems of control plants (M22) revealed that SUS activity was located in phloem and xylem. SUS activity as measured by in situ assays was significantly reduced in phloem and xylem of M18 plants. Down-regulation of SUS activity in M17 and M18 had only minor effects on plant dry weight or cell wall composition of stems. Neutral invertase in situ assays showed activity in stem vascular tissue with similar levels of activity in the control (M22) and the SUS down-regulated line (M18). The results suggest that neutral invertase activity in stem vascular tissue compensated for the down-regulation of SUS.


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