Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 3 de 3
Filter
Add more filters










Database
Language
Publication year range
1.
Appl Environ Microbiol ; 66(11): 4785-9, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11055924

ABSTRACT

We analyzed the genetic diversity of 531 Sinorhizobium meliloti strains isolated from nodules of Medicago sativa cultivars in two different Italian soils during 4 years of plant growth. The isolates were analyzed for DNA polymorphism with the random amplified polymorphic DNA method. The populations showed a high level of genetic polymorphism distributed throughout all the isolates, with 440 different haplotypes. Analysis of molecular variance allowed us to relate the genetic structure of the symbiotic population to various factors, including soil type, alfalfa cultivar, individual plants within a cultivar, and time. Some of these factors significantly affected the genetic structure of the population, and their relative influence changed with time. At the beginning of the experiment, the soil of origin and, even more, the cultivar significantly influenced the distribution of genetic variability of S. meliloti. After 3 years, the rhizobium population was altered; it showed a genetic structure based mainly on differences among plants, while the effects of soil and cultivar were not significant.


Subject(s)
Genetic Variation , Medicago sativa/microbiology , Sinorhizobium meliloti/growth & development , Sinorhizobium meliloti/genetics , DNA, Bacterial/analysis , DNA, Bacterial/genetics , Italy , Random Amplified Polymorphic DNA Technique/methods , Soil , Symbiosis
2.
Antonie Van Leeuwenhoek ; 73(1): 3-8, 1998 Jan.
Article in English | MEDLINE | ID: mdl-9602273

ABSTRACT

We analysed the genetic diversity of 270 Sinorhizobium meliloti strains isolated from nodules of three different Medicago sativa varieties, planted in three different Italian soils, combining the Analysis of Molecular Variance (AMOVA) with the Random Amplified Polymorphic DNA (RAPD) technique to estimate variance among RAPD patterns with the aim to draw an objective description of the population genetic structure. Results indicated that a general intraspecific genetic diversity was globally distributed among all the population, however a very high level of diversity was found among strains nodulating different Medicago sativa varieties. Moreover the distribution of the RAPD haplotypes among the plant varieties also showed to be non-random. The overall data indicated that the plant genotype is a major factor in shaping the genetic structure of this natural Rhizobium population.


Subject(s)
Genetic Variation , Medicago sativa/microbiology , Rhizobiaceae/genetics , Analysis of Variance , DNA, Bacterial/analysis , Genotype , Haplotypes , Italy , Medicago sativa/genetics , Phylogeny , Random Amplified Polymorphic DNA Technique , Rhizobiaceae/classification , Rhizobiaceae/isolation & purification , Rhizobiaceae/physiology , Soil Microbiology
3.
Appl Environ Microbiol ; 62(7): 2279-85, 1996 Jul.
Article in English | MEDLINE | ID: mdl-8779566

ABSTRACT

We investigated the genetic diversity of 96 Rhizobium meliloti strains isolated from nodules of four Medicago sativa varieties from distinct geographic areas and planted in two different northern Italian soils. The 96 isolates, which were phenotypically indistinguishable, were analyzed for DNA polymorphism with the following three methods: (i) a randomly amplified polymorphic DNA (RAPD) method, (ii) a restriction fragment length polymorphism (RFLP) analysis of the 16S-23S ribosomal operon spacer region, and (iii) an RFLP analysis of a 25-kb region of the pSym plasmid containing nod genes. Although the bacteria which were studied constituted a unique genetic population, a considerable level of genetic diversity was found. The new analysis of molecular variance (AMOVA) method was used to estimate the variance among the RAPD patterns. The results indicated that there was significant genetic diversity among strains nodulating different varieties. The AMOVA method was confirmed to be a useful tool for investigating the genetic variation in an intraspecific population. Moreover, the data obtained with the two RFLP methods were consistent with the RAPD results. The genetic diversity of the population was found to reside on the whole bacterial genome, as suggested by the RAPD analysis results, and seemed to be distributed on both the chromosome and plasmid pSym.


Subject(s)
Medicago sativa/microbiology , Sinorhizobium meliloti/genetics , Sinorhizobium meliloti/isolation & purification , Analysis of Variance , Base Sequence , Chromosome Mapping , Chromosomes, Bacterial/genetics , DNA Primers/genetics , DNA, Bacterial/genetics , DNA, Ribosomal/genetics , Genetic Variation , Italy , Molecular Sequence Data , Plasmids/genetics , Polymorphism, Restriction Fragment Length , RNA, Bacterial/genetics , RNA, Ribosomal, 16S/genetics , RNA, Ribosomal, 23S/genetics , Random Amplified Polymorphic DNA Technique , Soil Microbiology , Symbiosis
SELECTION OF CITATIONS
SEARCH DETAIL
...