Source: UNIVERSITY OF KENTUCKY submitted to NRP
HOST GENETIC CONTROL OF STRAIN-SPECIFIC NITROGEN FIXATION IN THE LEGUME-RHIZOBIAL SYMBIOSIS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
1001475
Grant No.
2014-67013-21573
Cumulative Award Amt.
$500,000.00
Proposal No.
2013-02902
Multistate No.
(N/A)
Project Start Date
Dec 1, 2013
Project End Date
Nov 30, 2018
Grant Year
2014
Program Code
[A1121]- Plant Health and Production and Plant Products: Understanding Plant-Associated Microorganisms
Recipient Organization
UNIVERSITY OF KENTUCKY
500 S LIMESTONE 109 KINKEAD HALL
LEXINGTON,KY 40526-0001
Performing Department
Plant and Soil Sciences
Non Technical Summary
Legumes have the remarkable ability to establish a symbiotic relationship with nitrogen-fixing soil bacteria, known as rhizobia. This mutualism culminates in the formation of a new plant organ, called the root nodule, within which the bacteria convert atmospheric nitrogen into ammonia, a biological form that can be directly consumed by the plant. One striking feature of the symbiosis is its high level of specificity. Such specificity can occur at the early phase of the interaction that is associated with bacterial infection and nodulation as well as at the late phase of nodule development that is related to nitrogen fixation. Genetic control of symbiosis specificity is complex, involving complex signal communication between the symbiotic partners. Despite recent advances in our understanding of the signaling pathways leading to root nodule development, the molecular mechanisms underlying natural variation in nitrogen fixation efficiency/specificity are largely unknown. The goal of this proposal is to explore host genetic control mechanisms underlying strain-specific nitrogen fixation in the legume-rhizobial symbiosis using the Medicago-Sinorhizobium model.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2011640104050%
2062499108050%
Knowledge Area
206 - Basic Plant Biology; 201 - Plant Genome, Genetics, and Genetic Mechanisms;

Subject Of Investigation
1640 - Alfalfa; 2499 - Plant research, general;

Field Of Science
1040 - Molecular biology; 1080 - Genetics;
Goals / Objectives
The overall goal of this proposal is to explore host genetic control mechanisms underlying strain-specific nitrogen fixation in the legume-rhizobial symbiosis using the Medicago-Sinorhizobium model. Specific objectives include: 1) Map-based cloning of Nfs1 (nitrogen fixation specificity 1), a host gene that regulates strain-specific nitrogen fixation in Medicago truncatula; 2) Molecular and biochemical characterization of Mt-Nfs1; and 3) Exploring genomic signatures of efficient nitrogen-fixing symbiosis.
Project Methods
The project will employ genetic, genomic, molecular, and biochemical approaches to understand mechanisms underlying symbiosis specificity.

Progress 12/01/13 to 11/30/18

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?I have been invited to present our research results multiple times during the perriod of this project: Genetic basis of symbiosis specificity in legumes. Shanxi Agricultural University, China, October 12, 2018. Genetic basis of symbiosis specificity in legumes. Liao-Cheng University, China, October 10, 2018. Genetic control of specificity in the legume-rhizobial symbiosis. The 24th North American Symbiotic Nitrogen Fixation Conference. Winnipeg, Manitoba, Canada, May 20-23, 2018 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Division of Plant Sciences, West Virginia University, Morgantown, WV, November 9, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China, July 26, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. National Maize Improvement Center, China Agricultural University, Beijing, China, July 25, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China, July 25, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China, July 21, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Yangzhou University, Yangzhou, China, July 19, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Shanxi Agricultural University, Taigu, China, July 11, 2017 Genetic control of symbiosis specificity in soybeans. The 16th Biennial Conference of the Molecular and Cellular Biology of the Soybean, Columbus, Ohio, August 7-10, 2016 Genetic control of symbiosis specificity in the legume-rhizobial mutualism. USDA-AFRI Project Directors' Meeting, Washington DC, June 30-July 1, 2016 Plant interactions with microbes: Dealing with friends, foes, and lovers. Shanxi University, Taiyuan, China, September 20, 2015 Plant interactions with microbes: Dealing with friends, foes, and lovers. The 2nd International Workshop on Agriculture and Agri-Food Safety, Yangzhou University, Yangzhou, China, September 17, 2015 Genetic control of symbiosis specificity in legumes. Shanxi Agricultural University, China, September 10, 2015 Plant interactions with microbes: Dealing with friends, foes, and lovers. Nanjing Agricultural University, China, September 26, 2014 Plant interactions with microbes: Dealing with friends, foes, and lovers. Shanxi Agricultural University, China, September 17, 2014 Genetic control of symbiosis specificity in the legume-rhizobial mutualism. , Saskatoon, Saskatchewan, Canada, July 7 - 11, 2014 . What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Themajor achievementfrom this projectwas the cloning of the first legume genes NFS1 and NFS2 in Medicago that regulate strain-specific nitrogen fixation (Yang et al. 2017, PNAS; Wang et al. 2017, PNAS; Wang et al. 2018, MPMI). These polymorphic genes encode nodule-specific cysteine-rich (NCR) peptides. In contrast to the predominant notion of NCR peptides as effectors of endosymbionts' differentiation to nitrogen-fixing bacteroids, we demonstrated that specific NCRs negatively regulate symbiotic persistence. NFS1 and NFS2 provoke bacterial cell death and early nodule senescence in an allele-specific and rhizobial strain-specific manner, and their function is dependent on host genetic background. Our findings provide novel insights into cross-kingdom signaling in host-symbiont interactions and make NCRs attractive agents for engineering legume-rhizobia pairs with improved agricultural properties.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Wang Q., Liu J., Zhu H (2018) Genetic and molecular mechanisms underlying symbiotic specificity in legume-rhizobium interactions. Front. Plant Sci. 9: 313.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Wang, Q., Liu, J., Li, H., Yang, S., K�rm�czi, P., Kereszt, A., Zhu H (2018). Nodule-specific cysteine-rich peptides negatively regulate nitrogen-fixing symbiosis in a strain-specific manner in Medicago truncatula. Mol. Plant-Microbe Interact. 31(2):240-248.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Yang S, Wang Q, Fedorova E, Liu J, Qin Q, Zheng Q, Price PA, Pan H, Wang D, Griffitts JS, Bisseling T, Zhu H (2017) Microsymbiont discrimination mediated by a host-secreted peptide in Medicago truncatula. Proceedings of the National Academy of Sciences USA 114 (26): 6848-6853.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Wang Q, Yang S, Liu J, Terecskei K, �brah�m E, Gomb�r A, Domonkos �, Sz?cs A, K�rm�czi P, Wang T, Fodor L, Mao L, Fei Z, Kondorosi �, Kal� P, Kereszt A, Zhu H (2017) Host-secreted antimicrobial peptide enforces symbiotic selectivity in Medicago truncatula. Proceedings of the National Academy of Sciences USA, 114(26): 6854-6859.


Progress 12/01/16 to 11/30/17

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? I have been invited to present our research results multiple times during the year of 2017. Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Division of Plant Sciences, West Virginia University, Morgantown, WV, November 9, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China, July 26, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. National Maize Improvement Center, China Agricultural University, Beijing, China, July 25, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China, July 25, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China, July 21, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Yangzhou University, Yangzhou, China, July 19, 2017 Host genetic control of symbiotic specificity in the legume-rhizobial interactions. Shanxi Agricultural University, Taigu, China, July 11, 2017 What do you plan to do during the next reporting period to accomplish the goals?We are continuing to ecucidate the roles of NCR peptides in regulating nitrogen-fixing specificity.

Impacts
What was accomplished under these goals? We have successfully cloned the NFS1 and NFS2 genes in M. truncatula that regulate nitrogen fixation specificity concerning Sinorhizobium meliloti Rm41. These polymorphic genes encode nodule-specific cysteine-rich (NCR) peptides. In contrast to the predominant notion of NCR peptides as effectors of endosymbionts' differentiation to nitrogen-fixing bacteroids, we demonstrate that specific NCRs negatively regulate symbiotic persistence. NFS1 and NFS2 provoke bacterial cell death and early nodule senescence in an allele-specific and rhizobial strain-specific manner, and their function is dependent on host genetic background. Our findings provide novel insights into cross-kingdom signaling in host-symbiont interactions and make NCRs attractive agents for engineering legume-rhizobia pairs with improved agricultural properties.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Yang S, Wang Q, Fedorova E, Liu J, Qin Q, Zheng Q, Price PA, Pan H, Wang D, Griffitts JS, Bisseling T, Zhu H (2017) Microsymbiont discrimination mediated by a host-secreted peptide in Medicago truncatula. Proc Natl Acad Sci USA 114 (26): 6848-6853.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Wang Q, Yang S, Liu J, Terecskei K, �brah�m E, Gomb�r A, Domonkos �, Sz?cs A, K�rm�czi P, Wang T, Fodor L, Mao L, Fei Z, Kondorosi �, Kal� P, Kereszt A, Zhu H (2017) Host-secreted antimicrobial peptide enforces symbiotic selectivity in Medicago truncatula. Proc Natl Acad Sci USA, 114(26): 6854-6859.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Wang, Q., Liu, J., Li, H., Yang, S., K�rm�czi, P., Kereszt, A., et al. (2017). Nodule-specific cysteine-rich peptides negatively regulate nitrogen-fixing symbiosis in a strain-specific manner in Medicago truncatula. Mol. Plant-Microbe Interact. Online. doi: 10.1094/MPMI-08-17-0207-R


Progress 12/01/15 to 11/30/16

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Genetic control of symbiosis specificity in soybeans. The 16th Biennial Conference of the Molecular and Cellular Biology of the Soybean, Columbus, Ohio, August 7-10, 2016 Genetic control of symbiosis specificity in the legume-rhizobial mutualism. USDA-AFRI Project Directors' Meeting, Washington DC, June 30-July 1, 2016 What do you plan to do during the next reporting period to accomplish the goals?Further characterization of the role of NFS1 and NFS2 in regulation of nitrogen fixation efficiency in Medicago.

Impacts
What was accomplished under these goals? The legume-rhizobial symbiosis results in the formation of root nodules that provide an ecological niche for nitrogen-fixing bacteria. However, plant-bacteria genotypic interactions can lead to wide variation in nitrogen fixation efficiency, and it is not uncommon that a bacterial strain forms functional (Fix+) nodules on one plant genotype but non-functional (Fix-) nodules on another. Host genetic control of this specificity is unknown. We have cloned the Medicago truncatula genes NFS1 and NFS2 that control the fixation-level incompatibility with the microsymbiont Sinorhizobium meliloti Rm41. These polymorphic genes encode nodule-specific cysteine-rich (NCR) peptides. In contrast to the known role of NCR peptides as effectors of endosymbionts' differentiation to nitrogen-fixing bacteroids, we demonstrate that specific NCRs control discrimination against incompatible microsymbionts. NFS1 and NFS2 provoke bacterial cell death and early nodule senescence in an allele-specific and rhizobial strain-specific manner, and their function is dependent on host genetic background. The manuscripts reporting theresults from this project have been submitted for publication.

Publications


    Progress 12/01/14 to 11/30/15

    Outputs
    Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Plant interactions with microbes: Dealing with friends, foes, and lovers. Yangzhou University, China, September 20, 2015 What do you plan to do during the next reporting period to accomplish the goals?We expect to clone the Nfs1 gene and publish the result.

    Impacts
    What was accomplished under these goals? We have mapped the candidate genes for Nfs1 within a 13-kb region on the Medicago truncatula chromosome 8 and are in the process to validate the candidate genes. We also identified a second locus that controls nitrogen fixation specifcity and mapped the locus within a 150-kb region on chromosome 8, and are also in the process of cloning the second gene.

    Publications


      Progress 12/01/13 to 11/30/14

      Outputs
      Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? The resultsfrom this project were disseminated through invited talks at conference and institutes. 1. Plant interactions with microbes: Dealing with friends, foes, and lovers. Nanjing Agricultural University, China, September 26, 2014 2. Plant interactions with microbes: Dealing with friends, foes, and lovers. Shanxi Agricultural University, China, September 17, 2014 3. Genetic control of symbiosis specificity in the legume-rhizobial mutualism. The 6th International Food Legumes Research Conference & 7th International Conference on Legume Genetics and Genomics, Saskatoon, Saskatchewan, Canada, July 7 - 11, 2014 What do you plan to do during the next reporting period to accomplish the goals? We will be able to clone the NFS1 gene and will continue to characterize the gene at molecular levels.

      Impacts
      What was accomplished under these goals? We have mapped the candidate genes within a 13-kb region on the Medicago truncatula chromosome 8 and are in the process to validate the candidate genes.

      Publications