Bacteria related to Bradyrhizobium yuanmingense from Ghana are effective groundnut micro-symbionts
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Date
2018
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Elsevier
Abstract
The identification of locally-adapted rhizobia for effective inoculation of grain legumes in Africa’s semiarid
regions is strategic for developing and optimizing cheap nitrogen fixation technologies for smallholder farmers.
This study was aimed at selecting and characterising effective native rhizobia, from Ghanaian soils for groundnut
(Arachis hypogaea L.) inoculation. From surface-disinfected root nodules of cowpea and groundnut plants grown
on farmers’ fields, 150 bacterial isolates were obtained, 30 of which were eventually found to nodulate
groundnut plants. After testing the symbiotic potential of these isolates on groundnut on sterilized substrate,
seven of them, designated as KNUST 1001–1007, were evaluated in an open field pot experiment using 15N labelled soil.
Although 15N dilution analyses did not indicate differences among treatments in the proportion of
nitrogen (N) derived from the atmosphere (%Ndfa), all seven strains increased total N derived from N2 fixation
by inoculated groundnut plants as compared to the non-inoculated control. Inoculation with KNUST 1002 led to
total N accumulation as high as that of the groundnut reference strain 32H1. Genetic characterisation of the
isolates by sequence analysis of 16S rRNA gene, 16S – 23S rRNA intergenic transcribed spacer (ITS) region and
nodC gene revealed that isolates KNUST 1003 and 1007 were related to Rhizobium tropici, a common bean
symbiont. The other five isolates, including KNUST 1002 belonged to the Bradyrhizobium genus, being closely
related to Bradyrhizobium yuanmingense. Therefore, this study revealed novel native Ghanaian rhizobia with
potential for the development of groundnut inoculants
Description
This article is Published by Elsevier, 2018 and is also available at https://doi.org/10.1016/j.apsoil.2018.03.003
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Citation
Applied Soil Ecology 127 (2018) 41- 50