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
                                            LIU, JUNQI - UNIVERSITY OF MINNESOTAitem
                                            Miller, Susanitem
                                            GRAHAM, MICHELLE - UNIVERSITY OF MINNESOTAitem
                                            Bucciarelli, Brunaitem
                                            CATALANO, CHRISTINA - UNIVERSITY OF DELAWAREitem
                                            SHERRIER, D - UNIVERSITY OF DELAWAREitem
                                            Samac, Deborah

                                                         - *Debby*item
                                            IVASHUTA, SERGEY - UNIVERSITY OF MINNESOTAitem
                                            FEDOROVA, MARIA - UNIVERSITY OF MINNESOTAitem
                                            MATSUMOTO, PETER - UNIVERSITY OF MINNESOTAitem
                                            GANTT, J - UNIVERSITY OF MINNESOTAitem
                                            Vance, Carroll
  Submitted to: Plant Physiology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 2/16/2006
                                    Publication  Date: 5/1/2006
                                    Citation: Liu, J., Miller, S.S., Graham, M., Bucciarelli, B., Catalano, C.M., Sherrier, D.J., Samac, D.A., Ivashuta, S., Fedorova, M., Matsumoto, P., Gantt, J.S., Vance, C.P. 2006. Recruitment of novel calcium-binding proteins for root nodule symbiosis in Medicago truncatula. Plant Physiology. 141:167-177.Interpretive Summary: Legume plants in symbiosis with the appropriate soil bacteria can convert atmospheric nitrogen gas to nitrogen fertilizer. This process, known as symbiotic nitrogen fixation, occurs in small wart-like structures on roots called nodules. For symbiotic nitrogen to occur the legume plant and the bacteria must be in communication by signaling to each other. Calcium is an important signal molecule in all biological systems. In studies reported here we investigated whether calcium-binding proteins were important in root nodule symbiosis. We demonstrated that the legume plant Medicago produces a group of unusual calcium-binding proteins which appear to surround the bacteria in symbiotic root nodules. In Medicago plants which are unable to make these calcium-binding proteins, symbiotic root nodules appear to be inefficient in nitrogen fixation. Upon analysis of Medicago DNA we found six genes that encode differing variants of the calcium-binding proteins, and the genes were located in close proximity to each other. These results are important because they are the first to document a new class of calcium-binding proteins that appear to be required for legume root nodule symbiosis. The findings show that the plant has developed proteins important in communicating with bacteria. Modification of the genes encoding these calcium-binding proteins may help improve symbiotic nitrogen fixation.
                                Technical Abstract: Legume-rhizobia symbiotic nitrogen (N2 ) fixation plays a critical role in sustainable N management in agriculture and in Earth's N cycle. Signaling between rhizobia and legumes initiates development of a unique plant organ, the root nodule, where the bacteria undergo endocytosis and become surrounded by a plant membrane to form a symbiosome (Sym). Between this membrane and the encased bacteria there exists a matrix-filled space (the symbiosome space, SymS) that is thought to contain a mixture of plant- and bacterially-derived proteins and about which little is known. Maintenance of the symbiosis state requires continuous communication between the plant and bacterial partners. Here we show in the model legume Medicago truncatula (Mt) that a novel family of six calmodulin-like proteins (CaMLs) are expressed specifically in root nodules, are localized within the SymS, and are required for effective symbiosis. All six nodule-specific CaML genes are clustered in the Mt genome along with two other nodule-specific genes, nodulin-22 and nodulin-25. Sequence comparisons and phylogenetic analysis suggests that an unequal recombination event occurred between nodulin-25 and a nearby calmodulin (CaM) gave rise to the first CaML and the gene family evolved by tandem duplication and divergence. The data provide striking evidence for the recruitment of a ubiquitious Ca2+-binding gene for symbiotic purposes.


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