Diversity and structure of bacterial community in rhizosphere of lima bean

The rhizosphere, i.e. the interface between plant roots and soil, harbors complex bacterial communities that can influence plant growth. Different plant species can have a distinct influence on the bacterial assembly. However, genetic traits found in the same plant species, i.e. different plant genotypes, can also drive bacterial communities in rhizosphere. In this study, bacterial communities in a sandy soil (Fluvisol) and rhizosphere of four lima bean (Phaseolus lunatus) genotypes were assessed by 16S rRNA gene sequencing. In general, Proteobacteria (23.3%), Actinobacteria (20.6%) and Firmicutes (12%) were the most dominant phyla in all samples. We found a distinct microbial structure between genotypes and bulk soil, with an increase of Proteobacteria and Actinobacteria, and a decrease of Firmicutes in the rhizosphere compared to the bulk soil. Also, the results showed that different biological and chemical drivers of each lima bean genotype influenced bacterial structure. Interestingly, each genotype enriched specific microbial taxa in rhizosphere. Our data revealed that plants influenced bacterial assembly in rhizosphere even at a genotype level. The findings gathered in this study can contribute to identify some specific bacterial groups associated with distinct genotypes of lima bean and can drive further studies about the contribution of these bacterial groups on lima bean growth.