Symbiosis island (SI) transfer and function in wild rhizobia

This project contains data and R code for \"The evolutionary genomics of incipient endosymbiosis in wild rhizobia bacteria\". We investigate the genetics, genomics, and fitness effects of incipient endosymbiosis in Mesorhizobium. Endosymbiosis has triggered major evolutionary transitions and drives ecosystem function. However, the genetics of early niche expansion into endosymbiosis and reciprocal fitness effects among novel endosymbiotic partners remain a dilemma, because subsequent evolution can obscure initial events in this transition. Rhizobia bacteria are useful to study incipient endosymbiosis because their ability to form nitrogen-fixing root nodules on plant roots is conferred by genes carried on mobile genetic elements (MGEs), such as the symbiosis island (SI). We generate novel endosymbioses by conjugating donor SIs into non-nodulating recipient strains and demonstrate that SI acquisition is sufficient to generate de novo root nodule forming endosymbionts. Most novel endosymbionts originate as commensals and one-third arise immediately as nitrogen-fixing mutualists. This dataverse includes data and analyses for the SI transfer experiment where we measure the number of SI gain transconjugants in matings between donor and recipient strains, as well as the greenhouse experiment where we use clonal inoculations of a subset of donor and recipient strains to assess plant and rhizobium fitness.