Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in Africa
<p>Abstract</p> <p>Background</p> <p>Cowpea is the most important food grain legume in Sub-Saharan Africa. However, no study has so far assessed rhizobial biodiversity and/or nodule functioning in relation to strain IGS types at the continent level. In this study, 9 cow...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2010-03-01
|
| Series: | BMC Microbiology |
| Online Access: | http://www.biomedcentral.com/1471-2180/10/89 |
| _version_ | 1818116218140229632 |
|---|---|
| author | Dakora Felix D Krasova-Wade Tatiana Belane Alphonsus K Pule-Meulenberg Flora |
| author_facet | Dakora Felix D Krasova-Wade Tatiana Belane Alphonsus K Pule-Meulenberg Flora |
| author_sort | Dakora Felix D |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Cowpea is the most important food grain legume in Sub-Saharan Africa. However, no study has so far assessed rhizobial biodiversity and/or nodule functioning in relation to strain IGS types at the continent level. In this study, 9 cowpea genotypes were planted in field experiments in Botswana, South Africa and Ghana with the aim of i) trapping indigenous cowpea root-nodule bacteria (cowpea "rhizobia") in the 3 countries for isolation, molecular characterisation using PCR-RFLP analysis, and sequencing of the 16S - 23S rDNA IGS gene, ii) quantifying N-fixed in the cowpea genotypes using the <sup>15</sup>N natural abundance technique, and iii) relating the levels of nodule functioning (i.e. N-fixed) to the IGS types found inside nodules.</p> <p>Results</p> <p>Field measurements of N<sub>2 </sub>fixation revealed significant differences in plant growth, δ<sup>15</sup>N values, %Ndfa and amounts of N-fixed between and among the 9 cowpea genotypes in Ghana and South Africa. Following DNA analysis of 270 nodules from the 9 genotypes, 18 strain IGS types were found. Relating nodule function to the 18 IGS types revealed significant differences in IGS type N<sub>2</sub>-fixing efficiencies. Sequencing the 16S - 23S rDNA gene also revealed 4 clusters, with cluster 2 forming a distinct group that may be a new <it>Bradyrhizobium </it>species. Taken together, our data indicated greater biodiversity of cowpea bradyrhizobia in South Africa relative to Botswana and Ghana.</p> <p>Conclusions</p> <p>We have shown that cowpea is strongly dependant on N<sub>2 </sub>fixation for its N nutrition in both South Africa and Ghana. Strain IGS type symbiotic efficiency was assessed for the first time in this study, and a positive correlation was discernible where there was sole nodule occupancy. The differences in IGS type diversity and symbiotic efficiency probably accounts for the genotype × environment interaction that makes it difficult to select superior genotypes for use across Africa. The root-nodule bacteria nodulating cowpea in this study all belonged to the genus <it>Bradyrhizobium</it>. Some strains from Southern Africa were phylogenetically very distinct, suggesting a new <it>Bradyrhizobium </it>species.</p> |
| first_indexed | 2024-12-11T04:19:01Z |
| format | Article |
| id | doaj.art-b58bb7692832470790fa20a3459bb987 |
| institution | Directory Open Access Journal |
| issn | 1471-2180 |
| language | English |
| last_indexed | 2024-12-11T04:19:01Z |
| publishDate | 2010-03-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Microbiology |
| spelling | doaj.art-b58bb7692832470790fa20a3459bb9872022-12-22T01:21:10ZengBMCBMC Microbiology1471-21802010-03-011018910.1186/1471-2180-10-89Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in AfricaDakora Felix DKrasova-Wade TatianaBelane Alphonsus KPule-Meulenberg Flora<p>Abstract</p> <p>Background</p> <p>Cowpea is the most important food grain legume in Sub-Saharan Africa. However, no study has so far assessed rhizobial biodiversity and/or nodule functioning in relation to strain IGS types at the continent level. In this study, 9 cowpea genotypes were planted in field experiments in Botswana, South Africa and Ghana with the aim of i) trapping indigenous cowpea root-nodule bacteria (cowpea "rhizobia") in the 3 countries for isolation, molecular characterisation using PCR-RFLP analysis, and sequencing of the 16S - 23S rDNA IGS gene, ii) quantifying N-fixed in the cowpea genotypes using the <sup>15</sup>N natural abundance technique, and iii) relating the levels of nodule functioning (i.e. N-fixed) to the IGS types found inside nodules.</p> <p>Results</p> <p>Field measurements of N<sub>2 </sub>fixation revealed significant differences in plant growth, δ<sup>15</sup>N values, %Ndfa and amounts of N-fixed between and among the 9 cowpea genotypes in Ghana and South Africa. Following DNA analysis of 270 nodules from the 9 genotypes, 18 strain IGS types were found. Relating nodule function to the 18 IGS types revealed significant differences in IGS type N<sub>2</sub>-fixing efficiencies. Sequencing the 16S - 23S rDNA gene also revealed 4 clusters, with cluster 2 forming a distinct group that may be a new <it>Bradyrhizobium </it>species. Taken together, our data indicated greater biodiversity of cowpea bradyrhizobia in South Africa relative to Botswana and Ghana.</p> <p>Conclusions</p> <p>We have shown that cowpea is strongly dependant on N<sub>2 </sub>fixation for its N nutrition in both South Africa and Ghana. Strain IGS type symbiotic efficiency was assessed for the first time in this study, and a positive correlation was discernible where there was sole nodule occupancy. The differences in IGS type diversity and symbiotic efficiency probably accounts for the genotype × environment interaction that makes it difficult to select superior genotypes for use across Africa. The root-nodule bacteria nodulating cowpea in this study all belonged to the genus <it>Bradyrhizobium</it>. Some strains from Southern Africa were phylogenetically very distinct, suggesting a new <it>Bradyrhizobium </it>species.</p>http://www.biomedcentral.com/1471-2180/10/89 |
| spellingShingle | Dakora Felix D Krasova-Wade Tatiana Belane Alphonsus K Pule-Meulenberg Flora Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in Africa BMC Microbiology |
| title | Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in Africa |
| title_full | Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in Africa |
| title_fullStr | Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in Africa |
| title_full_unstemmed | Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in Africa |
| title_short | Symbiotic functioning and bradyrhizobial biodiversity of cowpea (<it>Vigna unguiculata </it>L. Walp.) in Africa |
| title_sort | symbiotic functioning and bradyrhizobial biodiversity of cowpea it vigna unguiculata it l walp in africa |
| url | http://www.biomedcentral.com/1471-2180/10/89 |
| work_keys_str_mv | AT dakorafelixd symbioticfunctioningandbradyrhizobialbiodiversityofcowpeaitvignaunguiculataitlwalpinafrica AT krasovawadetatiana symbioticfunctioningandbradyrhizobialbiodiversityofcowpeaitvignaunguiculataitlwalpinafrica AT belanealphonsusk symbioticfunctioningandbradyrhizobialbiodiversityofcowpeaitvignaunguiculataitlwalpinafrica AT pulemeulenbergflora symbioticfunctioningandbradyrhizobialbiodiversityofcowpeaitvignaunguiculataitlwalpinafrica |