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Martinez-Romero E, Peix A, Hungria M, Mousavi SA, Martinez-Romero J, Young P. Guidelines for the description of rhizobial symbiovars. Int J Syst Evol Microbiol 2024; 74:006373. [PMID: 38743471 PMCID: PMC11165908 DOI: 10.1099/ijsem.0.006373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 04/25/2024] [Indexed: 05/16/2024] Open
Abstract
Rhizobia are bacteria that form nitrogen-fixing nodules in legume plants. The sets of genes responsible for both nodulation and nitrogen fixation are carried in plasmids or genomic islands that are often mobile. Different strains within a species sometimes have different host specificities, while very similar symbiosis genes may be found in strains of different species. These specificity variants are known as symbiovars, and many of them have been given names, but there are no established guidelines for defining or naming them. Here, we discuss the requirements for guidelines to describe symbiovars, propose a set of guidelines, provide a list of all symbiovars for which descriptions have been published so far, and offer a mechanism to maintain a list in the future.
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Affiliation(s)
| | - Alvaro Peix
- Instituto de Recursos Naturales y Agrobiología, IRNASA-CSIC, Salamanca, Spain
- Interacción Planta-Microorganismo, Universidad de Salamanca, Unidad Asociada al CSIC por el IRNASA, Salamanca, Spain
| | | | | | | | - Peter Young
- Department of Biology, University of York, York YO10 5DD, UK
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Khairnar M, Hagir A, Parmar K, Sayyed RZ, James EK, Rahi P. Phylogenetic diversity and plant growth-promoting activities of rhizobia nodulating fenugreek (Trigonella foenum-graecum Linn.) cultivated in different agroclimatic regions of India. FEMS Microbiol Ecol 2022; 98:6526309. [PMID: 35142840 DOI: 10.1093/femsec/fiac014] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 12/15/2021] [Accepted: 02/08/2022] [Indexed: 11/15/2022] Open
Abstract
Fenugreek (Trigonella foenum-graecum Linn.), is an extensively cultivated legume crop used as a herb, spice, and traditional medicine in India. The symbiotic efficiency and plant growth-promoting potential of fenugreek rhizobia depend on the symbiont strain and environmental factors. We isolated 176 root-nodulating bacteria from fenugreek cultivated in different agroclimatic regions of India. MALDI-TOF MS-based identification and phylogenetic analyses based on 16S rRNA and five housekeeping genes classified the fenugreek-rhizobia as Ensifer (Sinorhizobium) meliloti. However, the strains represent separate sub-lineages of E. meliloti, distinct from all reported sub-lineages across the globe. We also observed the spatial distribution of fenugreek rhizobia, as the three sub-lineages of E. meliloti recorded during this study were specific to their respective agroclimatic regions. According to the symbiotic gene (nodC and nifH) phylogenies, all three sub-lineages of E. meliloti harboured symbiotic genes similar to symbiovar meliloti; as with the housekeeping genes, these also revealed a spatial distribution for different clades of sv. meliloti. The strains could nodulate fenugreek plants and they showed plant growth-promoting potential. Significant differences were found in the plant growth parameters in response to inoculation with the various strains, suggesting strain-level differences. This study demonstrates that fenugreek rhizobia in India are diverse and spatially distributed in different agro-climatic regions.
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Affiliation(s)
- Mitesh Khairnar
- National Centre for Microbial Resource, National Centre for Cell Science, Pune 411007, India
| | - Ashwini Hagir
- National Centre for Microbial Resource, National Centre for Cell Science, Pune 411007, India
| | - Krupa Parmar
- National Centre for Microbial Resource, National Centre for Cell Science, Pune 411007, India
| | - Riyazali Zafarali Sayyed
- Department of Microbiology, PSGVP Mandal's, Arts, Science, and Commerce College, Shahada 425409, India
| | - Euan K James
- The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Praveen Rahi
- National Centre for Microbial Resource, National Centre for Cell Science, Pune 411007, India
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León-Barrios M, Flores-Félix JD, Pérez-Yépez J, Ramirez-Bahena MH, Pulido-Suárez L, Igual JM, Velázquez E, Peix Á. Definition of the novel symbiovar canariense within Mesorhizobium neociceri sp. nov., a new species of genus Mesorhizobium nodulating Cicer canariense in the "Caldera de Taburiente" National Park (La Palma, Canary Islands). Syst Appl Microbiol 2021; 44:126237. [PMID: 34332368 DOI: 10.1016/j.syapm.2021.126237] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 11/26/2022]
Abstract
Cicer canariense is a highly promiscuous wild chickpea nodulated by Mesorhizobium strains in La Palma Island located at Canary archipelago. Four of these strains, CCANP34, CCANP35T, CCANP38 and CCANP95 belong to a group phylogenetically close to Mesorhizobium caraganae with 100% similarity values in the 16S rRNA gene. However, the genomes of the strains CCANP35T and M. caraganae LMG 24397T obtained in this work showed ANIb and dDDH values of 90.02% and 44.1%, respectively. These values are lower than those currently accepted for different bacterial species showing that the Canarian strains do not belong to the species M. caraganae. The Canarian strains also differ from M. caraganae in the amounts of several fatty acids and in several phenotypic traits. Based on the obtained results the Canarian strains belong to a novel species for which we propose the name Mesorhizobium neociceri sp. nov. and whose type strain is CCANP35T. The results of the phylogenetic analyses of nodC and nifH symbiotic genes showed that the Canarian strains represent a novel symbiovar within genus Mesorhizobium phylogenetically divergent to that encompassing M. caraganae. We propose the names canariense and caraganae for the symbiovars encompassing the strains of M. neociceri and M. caraganae, respectively.
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Affiliation(s)
- Milagros León-Barrios
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Tenerife, Spain
| | | | - Juan Pérez-Yépez
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Tenerife, Spain
| | | | - Laura Pulido-Suárez
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Tenerife, Spain
| | - José M Igual
- IRNASA-CSIC, Salamanca, Spain; Unidad Asociada Grupo de Interacción Planta-Microorganismo, Universidad de Salamanca-IRNASA-CSIC, Salamanca, Spain
| | - Encarna Velázquez
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain; Unidad Asociada Grupo de Interacción Planta-Microorganismo, Universidad de Salamanca-IRNASA-CSIC, Salamanca, Spain; Instituto Hispanoluso de Investigaciones Agrarias (CIALE), Universidad de Salamanca, Salamanca, Spain
| | - Álvaro Peix
- IRNASA-CSIC, Salamanca, Spain; Unidad Asociada Grupo de Interacción Planta-Microorganismo, Universidad de Salamanca-IRNASA-CSIC, Salamanca, Spain
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