Data from: Host investment into symbiosis varies among genotypes of the legume Acmispon strigosus, but host sanctions are uniform

Efficient host control predicts the extirpation of ineffective symbionts, but they are nonetheless widespread in nature. We tested three hypotheses for the maintenance of symbiotic variation in rhizobia that associate with a native legume: 1) partner mismatch between host and symbiont, such that symbiont effectiveness varies with host genotype, 2) resource satiation, whereby extrinsic sources of nutrients relax host control, and 3) variation in host control among host genotypes. We inoculated Acmispon strigosus from six populations with three Bradyrhizobium strains that vary in symbiotic effectiveness on sympatric hosts. We measured proxies of host and symbiont fitness in single- and co-inoculations under fertilization treatments of zero added nitrogen and near-growth-saturating nitrogen. We examined two components of host control: 'host investment' into nodule size during single- and co-inoculations, and 'host sanctions' against less effective strains during co-inoculations. The Bradyrhizobium strains displayed conserved growth effects on hosts, and host control did not decline under experimental fertilization. Host sanctions were robust in all hosts, but host lines from different populations varied significantly in measures of host investment in both single- and co-inoculation experiments. Variation in host investment could promote variation in symbiotic effectiveness and prevent the extinction of ineffective Bradyrhizobium from natural populations.Wendlandt_2018_New_Phytologist_Raw_DataRaw data collected from individual plants (per-plant raw data) and individual nodules (per-nodule raw data) corresponding to Wendlandt et al 2018 (New Phytologist). Per-plant data include measures of leaf number at time of inoculation, shoot and root mass at time of harvest, total number and dry mass of root nodules, and nitrogen isotopic data from leaf tissue. Per-nodule data include nodule area, number of rhizobial cells per nodule (for nodules from plants inoculated with a single strain), and number of rhizobial colonies identified as particular strains (for nodules from plants co-inoculated with three strains).Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: DEB-115027