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1.
Syst Appl Microbiol ; 41(3): 251-259, 2018 May.
Article in English | MEDLINE | ID: mdl-29452714

ABSTRACT

The identification and conservation of indigenous rhizobia associated with legume plants and their application as biofertilizers is becoming an agricultural worldwide priority. However, little is known about the genetic diversity and phylogeny of rhizobia in Romania. In the present study, the genetic diversity and population composition of Rhizobium leguminosarum symbiovar trifolii isolates from 12 clover plants populations located across two regions in Romania were analyzed. Red clover isolates were phenotypically evaluated and genotyped by sequencing 16S rRNA gene, 16S-23S intergenic spacer, three chromosomal genes (atpD, glnII and recA) and two plasmid genes (nifH and nodA). Multilocus sequence typing (MLST) analysis revealed that red clover plants are nodulated by a wide genetic diversity of R. leguminosarum symbiovar trifolii sequence types (STs), highly similar to the ones previously found in white clover. Rhizobial genetic variation was found mainly within the two clover populations for both chromosomal and plasmid types. Many STs appear to be unique for this region and the genetic composition of rhizobia differs significantly among the clover populations. Furthermore, our results showed that both soil pH and altitude contributed to plasmid sequence type composition while differences in chromosomal composition were affected by the altitude and were strongly correlated with distance.


Subject(s)
Genetic Variation , Medicago/microbiology , Phylogeny , Rhizobium leguminosarum/genetics , Root Nodules, Plant/microbiology , Trifolium/microbiology , Altitude , DNA, Bacterial/genetics , Genes, Bacterial , Genetics, Population , Multilocus Sequence Typing , RNA, Ribosomal, 16S/genetics , Romania , Sequence Analysis, DNA , Soil/chemistry , Symbiosis
2.
Antonie Van Leeuwenhoek ; 111(1): 135-153, 2018 Jan.
Article in English | MEDLINE | ID: mdl-28905167

ABSTRACT

The symbiotic nitrogen fixing legumes play an essential role in sustainable agriculture. White clover (Trifolium repens L.) is one of the most valuable perennial legumes in pastures and meadows of temperate regions. Despite its great agriculture and economic importance, there is no detailed available information on phylogenetic assignation and characterization of rhizobia associated with native white clover plants in South-Eastern Europe. In the present work, the diversity of indigenous white clover rhizobia originating in 11 different natural ecosystems in North-Eastern Romania were assessed by a polyphasic approach. Initial grouping showed that, 73 rhizobial isolates, representing seven distinct phenons were distributed into 12 genotypes, indicating a wide phenotypic and genotypic diversity among the isolates. To clarify their phylogeny, 44 representative strains were used in sequence analysis of 16S rRNA gene and IGS fragments, three housekeeping genes (atpD, glnII and recA) and two symbiosis-related genes (nodA and nifH). Multilocus sequence analysis (MLSA) phylogeny based on concatenated housekeeping genes delineated the clover isolates into five putative genospecies. Despite their diverse chromosomal backgrounds, test strains shared highly similar symbiotic genes closely related to Rhizobium leguminosarum biovar trifolii. Phylogenies inferred from housekeeping genes were incongruent with those of symbiotic genes, probably due to occurrence of lateral transfer events among native strains. This is the first polyphasic taxonomic study to report on the MLSA-based phylogenetic diversity of indigenous rhizobia nodulating white clover plants grown in various soil types in South-Eastern Europe. Our results provide valuable taxonomic data on native clover rhizobia and may increase the pool of genetic material to be used as biofertilizers.


Subject(s)
Genetic Variation , Phylogeny , Rhizobium leguminosarum/classification , Rhizobium leguminosarum/genetics , Trifolium/microbiology , Biodiversity , Genes, Bacterial , Genes, Essential , Genome, Bacterial , Genomics/methods , Molecular Typing , Multilocus Sequence Typing , Phenotype
3.
Acta Biol Hung ; 66(3): 316-25, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26344027

ABSTRACT

The application of commercial rhizobial inoculants to legume crops is proving to be an alternative to synthetic fertilizer use. The challenge for sustainable agriculture resides in the compatibility between crop, inoculants and environmental conditions. The evaluation of symbiotic efficiency and genetic diversity of indigenous rhizobial strains could lead to the development of better inoculants and increased crop production. The genetic variability of 32 wild indigenous rhizobial isolates was assessed by RAPD (Random Amplified Polymorphic DNA). The strains were isolated from red clover (Trifolium pratense L.) nodules from two distinct geographical regions of Northern and Eastern Romania. Three decamer primers were used to resolve the phylogenetic relationships between the investigated isolates. Cluster analysis revealed a high diversity; most strains clustered together based on their geographical location.


Subject(s)
Genetic Variation , Random Amplified Polymorphic DNA Technique , Rhizobium leguminosarum/genetics , Symbiosis/physiology , Trifolium/microbiology
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