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Ndungu SM, Messmer MM, Ziegler D, Thuita M, Vanlauwe B, Frossard E, Thonar C. Evaluation of MALDI-TOF mass spectrometry for the competitiveness analysis of selected indigenous cowpea (Vigna unguiculata L. Walp.) Bradyrhizobium strains from Kenya. Appl Microbiol Biotechnol 2018; 102:5265-5278. [PMID: 29696334 DOI: 10.1007/s00253-018-9005-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 01/21/2023]
Abstract
Cowpea N2 fixation and yield can be enhanced by selecting competitive and efficient indigenous rhizobia. Strains from contrasting agro-ecologies of Kilifi and Mbeere (Kenya) were screened. Two pot experiments were established consisting of 13 Bradyrhizobium strains; experiment 1 (11 Mbeere + CBA + BK1 from Burkina Faso), experiment 2 (12 Kilifi + CBA). Symbiotic effectiveness was assessed (shoot biomass, SPAD index and N uptake). Nodule occupancy of 13 simultaneously co-inoculated strains in each experiment was analyzed by matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) to assess competitiveness. Strains varied in effectiveness and competitiveness. The four most efficient strains were further evaluated in a field trial in Mbeere during the 2014 short rains. Strains from bacteroids of cowpea nodules from pot and field experiments were accurately identified as Bradyrhizobium by MALDI-TOF based on the SARAMIS™ database. In the field, abundant indigenous populations 7.10 × 103 rhizobia g-1 soil, outcompeted introduced strains. As revealed by MALDI-TOF, indigenous strains clustered into six distinct groups (I, II, III, IV, V and VI), group III were most abundant occupying 80% of nodules analyzed. MALDI-TOF was rapid, affordable and reliable to identify Bradyrhizobium strains directly from nodule suspensions in competition pot assays and in the field with abundant indigenous strains thus, its suitability for future competition assays. Evaluating strain competitiveness and then symbiotic efficacy is proposed in bioprospecting for potential cowpea inoculant strains.
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Affiliation(s)
- Samuel Mathu Ndungu
- Institute of Agricultural Sciences, ETH Zurich, Plant Nutrition group, Eschikon 33, CH-8315, Lindau, Switzerland. .,Research Institute of Organic Agriculture (FiBL), Ackerstrasse 113, CH-5070, Frick, Switzerland. .,International Institute of Tropical Agriculture (IITA), c/o ICIPE Campus, P.O. Box 30772-00100, Nairobi, Kenya.
| | - Monika M Messmer
- Research Institute of Organic Agriculture (FiBL), Ackerstrasse 113, CH-5070, Frick, Switzerland
| | - Dominik Ziegler
- Mabritec AG, Lörracherstrasse 50, CH-4125, Riehen, Switzerland
| | - Moses Thuita
- International Institute of Tropical Agriculture (IITA), c/o ICIPE Campus, P.O. Box 30772-00100, Nairobi, Kenya
| | - Bernard Vanlauwe
- International Institute of Tropical Agriculture (IITA), c/o ICIPE Campus, P.O. Box 30772-00100, Nairobi, Kenya
| | - Emmanuel Frossard
- Institute of Agricultural Sciences, ETH Zurich, Plant Nutrition group, Eschikon 33, CH-8315, Lindau, Switzerland
| | - Cécile Thonar
- Research Institute of Organic Agriculture (FiBL), Ackerstrasse 113, CH-5070, Frick, Switzerland. .,AgroBioChem Department, Gembloux Agro-Bio Tech, University of Liège, B-5030, Gembloux, Belgium.
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Sánchez-Cañizares C, Palacios J. Construction of a marker system for the evaluation of competitiveness for legume nodulation in Rhizobium strains. J Microbiol Methods 2013; 92:246-9. [PMID: 23305927 DOI: 10.1016/j.mimet.2012.12.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 12/21/2012] [Accepted: 12/21/2012] [Indexed: 11/21/2022]
Abstract
A marker system has been set up for the analysis of competitiveness of Rhizobium leguminosarum strains for legume nodulation. The strains generated incorporate gusA and celB marker genes at identical positions and allow efficient scoring of single and double infections. Based on this system, we have found that strain UPM791 outcompetes 3841 for nodulation in pea. This technique will be useful to determine the effect of different traits on competitiveness.
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Affiliation(s)
- Carmen Sánchez-Cañizares
- Centro de Biotecnología y Genómica de Plantas (C.B.G.P.), and Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40-km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain
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