Horizontal Gene Transfer (HGT) in rhizobia

HGT (Horizontal Gene Transfer) stands as the primary driver of genetic variation among Bacteria, facilitating the exchange of alleles within populations or genes across bacterial species. In symbiotic bacteria like nitrogen-fixing rhizobia, these genomic exchanges can profoundly impact their relationship with eukaryotic hosts, particularly affecting crucial processes such as nodulation and nitrogen fixation. My research focuses on detecting HGT events, unraveling their molecular mechanisms, assessing their impact on genetic diversity, and exploring the ecological contexts in which they occur.

The figure illustrates the detection of significant HGT events (depicted as edges in the network) within Sinorhizobium meliloti, spanning across its replicons (chromosome, chromid, megaplasmid) and strains (represented and grouped as nodes in the network) through homologous recombination. Notably, the graph reveals that, irrespective of their phylogenetic background (as depicted on the left), chromosomes exhibit a tendency to exchange more DNA with megaplasmids than with chromids. This observation sheds light on the preferential genetic exchange patterns within this bacterial species (Cerón-Romero et al, In prep).

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