A stydy of Rhizobium leguminosarum biovar trifolii populations from soil extracts using randomly amplified polymorphic DNA profiles

1995 ◽  
Vol 41 (4-5) ◽  
pp. 336-344 ◽  
Author(s):  
Malcolm Dye ◽  
Leif Sket ◽  
Lance R. Mytton ◽  
Ann Cresswell ◽  
Stephen P. Harrison ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rapd Analysis ◽  
Dna Amplification ◽  
Differential Centrifugation ◽  
Randomly Amplified Polymorphic Dna ◽  
Phenotypic Characteristics ◽  
Soil Extracts ◽  
Dna Profiles ◽  
Rapd Fragment ◽  
Rhizobium Leguminosarum Biovar Trifolii

This study has shown that isolates of Rhizobium leguminosarum biovar trifolii can be grouped on the basis of their randomly amplified polymorphic DNA (RAPD) fragment patterns. Evidence is presented that these groups are not entirely arbitrary but are consistent with other genetic and phenotypic characteristics. RAPD analysis has been used to assess the efficiency of a dispersion and differential centrifugation procedure used to extract bacteria from soil. Whilst the major groups of Rhizobium isolates in soils were also found in the extracts, some of the others were missing. This is also reflected in the finding, made by measuring abundance of organisms, that as many Rhizobium isolates are left in the residue as appear in the supernatant; more dispersion steps, possibly with different dispersants, are needed to maximize extraction. The technique has also demonstrated that dispersing soil by simply shaking it in water not only underestimates the numbers of Rhizobium isolates present but also masks much of their diversity.Key words: Rhizobium, DNA amplification, random primers, bacterial extraction.

Phylogenetic grouping and identification of Rhizobium isolates on the basis of random amplified polymorphic DNA profiles

1993 ◽  
Vol 39 (7) ◽  
pp. 665-673 ◽  
Author(s):  
John J. Dooley ◽  
Stephen P. Harrison ◽  
Lance R. Mytton ◽  
Malcolm Dye ◽  
Ann Cresswell ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Random Amplified Polymorphic Dna ◽  
Dna Amplification ◽  
Distinct Group ◽  
Principal Coordinate Analysis ◽  
The Other ◽  
Phylogenetic Grouping ◽  
Dna Profiles ◽  
Selection Of

Through the use of a single, random 15mer as a primer, between 1 and 12 DNA amplification products were obtained per strain from a selection of 84 Rhizobium and Bradyrhizobium isolates. A principal-coordinate analysis was used to analyse the resulting amplified DNA profiles and it was possible to assign isolates to specific groupings. Within the species Rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped together. Isolates of Rhizobium meliloti and Bradyrhizobium species formed their own clear, specific groups. Although it was possible to identify individual isolates on the basis of differences in their amplified DNA profiles, there was evidence that some amplified segments were conserved among individuals at the biovar and species levels.Key words: Rhizobium, DNA amplification, random primers.

Slow rehydration improves the recovery of dried bacterial populations

1992 ◽  
Vol 38 (6) ◽  
pp. 520-525 ◽  
Author(s):  
J. W. Kosanke ◽  
R. M. Osburn ◽  
G. I. Shuppe ◽  
R. S. Smith
Keyword(s):  
Relative Humidity ◽  
Rhizobium Leguminosarum ◽  
Moisture Absorption ◽  
Rhizobium Meliloti ◽  
Bacterial Populations ◽  
Bulk Powder ◽  
Alfalfa Seed ◽  
Powder Samples ◽  
Cellular Stresses ◽  
Rhizobium Leguminosarum Biovar Trifolii

Slow rehydration of bacteria from dried inoculant formulations provided higher viable counts than did rapid rehydration. Estimates were higher when clay and peat powder formulations of Rhizobium meliloti, Rhizobium leguminosarum biovar trifolii, and Pseudomonas putida, with water activities between 0.280 and 0.650, were slowly rehydrated to water activities of approximately 0.992 before continuing the dilution plating sequence. Rhizobium meliloti populations averaged 6.8 × 108 cfu/g and 1328 cfu/alfalfa seed greater when slowly rehydrated from bulk powder and preinoculated seeds, respectively. Bulk powder samples were slowly rehydrated to 0.992 water activity by the gradual addition of diluent, followed by a 10-min period for moisture equilibration. Preinoculated seed samples were placed in an environmental chamber at 24 °C with relative humidity greater than 80% for 1 h to allow moisture absorption. "Upshock," osmotic cellular stresses that occur during rehydration, was reduced when dried microbial formulations were slowly rehydrated and equilibrated before becoming fully hydrated in the dilution plating sequence. These procedures may also be applicable when estimating total viable bacterial populations from dried soil or other dry formulations. Key words: rehydration procedure, microbial rehydration, desiccation, Rhizobium, Pseudomonas.

Genetic variability within isolates of Colletotrichum lindemuthianum belonging to race 65 from the state of Minas Gerais, Brazil

Biologia ◽  
2008 ◽  
Vol 63 (2) ◽  
Author(s):  
Francine Ishikawa ◽  
Elaine Souza ◽  
Livia Davide
Keyword(s):  
Rapd Analysis ◽  
Anastomosis Group ◽  
Minas Gerais ◽  
Great Variability ◽  
The State ◽  
Colletotrichum Lindemuthianum ◽  
Randomly Amplified Polymorphic Dna ◽  
Dice Coefficient ◽  
The Common ◽  
Pathogenic Variability

AbstractColletotrichum lindemuthianum, the causal agent of anthracnose in the common bean (Phaseolus vulgaris), presents a wide genetic and pathogenic variability that gives rise to complications in the development of resistant bean cultivars. The aim of this study was to identify the variability within race 65 of C. lindemuthianum, the race most commonly encountered in Brazil, through randomly amplified polymorphic DNA (RAPD) and anastomosis analyses. Thirteen isolates of race 65, collected in different years and from various host cultivars located in diverse areas of the state of Minas Gerais, Brazil, were investigated. Twenty-four RAPD primers were employed and 83 polymorphic bands amplified. Genetic similarities were estimated from the Sorensen-Dice coefficient and ranged from 0.54 to 0.82. The dendrogram obtained by cluster analysis classified the isolates into 11 separate groups. For the purposes of the analysis of anastomosis, isolates were considered to be compatible when the fusion of hyphae from different isolates could be observed. The proportion of compatible reactions for each isolate was estimated and similarity estimates, based on the Russel & Rao coefficient, ranged from 0.28 to 0.85. Isolates were classified into 11 anastomosis groups, 10 of which were formed by only one isolate. Although isolates LV61, LV73 and LV58 were classified in the same anastomosis group, they were genetically distinct according to RAPD analysis. Results from both RAPD and anastomosis analyses revealed great variability within C. lindemuthianum race 65.

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