Microbial community structure in the rhizosphere of the orphan legume Kersting’s groundnut [Macrotyloma geocarpum (Harms) Marechal & Baudet]

The presence of microbial communities in the rhizosphere of plants is an important determinant of plant health and soil organic matter composition. Plant species play significant roles in selecting the specific microbial communities that inhabit the root zone. However, till now, there is no solid information regarding the presence of specific plant-microbiome in the rhizosphere of many plants, especially under-exploited and under-researched species such as Kersting’s groundnut. This study assessed the effect of five Kersting’s groundnut landraces on the structure of microbial communities in rhizosphere of field-grown plants. The five tested Kersting’s groundnut landraces (Belane Mottled, Boli, Funsi, Puffeun and Heng Red Mottled) were found to exert a marked selective influence on bacteria associated with their rhizospheres, measured using 16S rDNA MiSeq illumina sequencing. Community differences in microbial composition and relative abundance were both significant. Numerous phyla in the rhizosphere were affected by the test landraces. Except for Belane mottled whose rhizospheres were dominated by Proteobacteria, the rhizosphere soils of the other landraces were dominated by Bacteroidetes. With the exception of landrace Puffeun which showed only Mesorhizobium in its rhizosphere, all the other test landraces revealed the presence of Bradyrhizobium and Rhizobium species of alpha Proteobacteria. Furthermore, the rhizosphere of all landraces were abundant in species of the indole-3-acetic–acid producing Sphingomonas and cellulose-degrading Fibrobacteres. The results of this study suggest that Kersting’s groundnut landraces can shape bacterial community composition in the rhizosphere via plant-related changes in the rhizosphere soil.