Abstract
The genetic diversity and identification of slow- and fast- growing soybean root nodule
bacterial isolates from different agro-climatic regions in Mpumalanga, Limpopo and Gauteng
Provinces of South Africa were evaluated. The 16S-rDNA-RFLP analysis of 100 rhizobial
isolates and eight reference type strains placed the isolates into six major clusters, and
revealed their site-dependent genomic diversity. Sequence analysis of single and concatenated
housekeeping genes (atpD, glnII and gyrB), as well as the symbiotic gene nifH captured a
considerably higher level of genetic diversity and indicated the dominance of Bradyrhizobium
diazoefficiens and Bradyrhizobium japonicum in Mpumalanga, Limpopo and Gauteng Provinces. Gene sequence similarities of isolates with type strains of Bradyrhizobium ranged
from 97.3 to 100% for the 16S rDNA, and 83.4 to 100% for the housekeeping genes. The
glnII gene phylogeny showed discordance with the other genes, suggesting lateral gene
transfer or recombination events. Concatenated gene sequence analysis showed that most of
the isolates did not align with known type strains and might represent new species from South
Africa. This underscores the high genetic variability associated with soybean Bradyrhizobium
in South African soils, and the presence of an important reservoir of novel soybean-nodulating
bradyrhizobia in the country. In this study, the grouping of isolates was influenced by site
origin, with Group I isolates originating from Limpopo Province and Group II and III from
Mpumlanga Province in the 16S rDNA-RFLP analysis.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001977 |
| Date | 01 June 2016 |
| Creators | Naamala, J, Jaiswal, SK, Dakora, FD |
| Publisher | Systematic and Applied Microbiology |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | Systematic and Applied Microbiology |
| Relation | Researchgate |
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