Systems genetics of partner quality: Quantitative variation in gene expression and qualitative variation in plasmid-borne gene clusters underlies symbiosis variation

We leverage a model nitrogen-fixing plant symbiont and integrate genomics, phenotypes, and gene expression data to associate sets of gene clusters, which are frequently gained and lost in natural populations, with plant growth. We reveal novel structural and modular genetic processes with implications for the function and inheritance of symbiosis function in plant-microbe interactions. Overall design: In single-inoculation experiments, two plant genotypes of Medicago truncatula, A17 and DZA, were inoculated with 20 naturally occurring strains of Sinorhizobium meliloti.