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
                                            TESFAYE, MESFIN - UNIVERSITY OF MINNESOTAitem
                                            Vance, Carrollitem
                                            ALLAN, D - UNIVERSITY OF MINNESOTAitem
                                            Samac, Deborah

                                                         - *Debby*
  Submitted to: North American Alfalfa Improvement Conference
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 7/17/2000
                                    Publication  Date: N/A
                                    Citation: N/AInterpretive Summary:
                                Technical Abstract: Aluminum (Al) toxicity is a major factor limiting crop production in acid soils, which make up about 40% of the world's arable land. Aluminum inhibits root growth and uptake of water and nutrients. The roots of some acid soil tolerant crop varieties secrete organic acids that chelate Al and prevent uptake of Al by the root apex. In an effort to increase organic  acid secretion in alfalfa, we produced alfalfa using nodule enhanced forms of malate dehydrogenase (neMDH) and phosphoenolpyruvate carboxylase (nePEPC)cDNAs under the control of the CaMV 35S promoter. We identified lines with higher MDH and PEPC enzyme activity, enzyme-protein and mRNA transcript levels. Plants overexpressing neMDH showed considerably higher overall organic acid synthesis and exudation. Roots of these transgenic lines showed up to 6.5-fold higher amounts of oxalate, citrate, succinate and malate than control plants. Tolerance to Al by selected lines was  tested using root elongation over a 24-hour period. Relative root growth o selected lines in a 50 uM AlCl3 hydroponic solution, also containing 0.5 mM CaCl2, pH 4.3, was 3.4-fold greater than relative root growth of wild type plants. When plants were grown in pots filled with a highly weathered soil (pHH2O = 4.0, AlKCl = 71 ppm), shoot and root dry weight of transgenic plants increased up to 1.5-fold over controls. An alfalfa germplasm with increased acid tolerance, GA-AT, was developed previously by recurrent selection. Root organic acid profiles of both GA-AT and control alfalfa plants were similar, suggesting that the mechanism of Al tolerance in GA-AT may not involve enhanced organic acid release. F1 progeny of crosses between GA-AT and selected transgenic lines are being evaluated for Al tolerance and organic acid synthesis.


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