Nitrogen fertilization nullifies host sanctions against non-fixing rhizobia and drives divestment from symbiosis in Lotus japonicus

Plants and animals house microbes that provide critical nutrients, but little is known about host control over microbial cooperation when resources are also accessed from the environment. Changes in nutrient access can challenge the host’s ability to detect and selectively reward beneficial partners, destabilizing symbiosis. Legumes acquire nitrogen from soil and from symbiosis with rhizobia, but it is unclear if extrinsic sources of nitrogen interfere with host control systems. We inoculated the legume, Lotus japonicus, with rhizobia bearing nitrogen fixation or nitrogen metabolism knockouts, and factorially varied molecular sources of nitrogen fertilizer. Lotus hosts selectively rewarded beneficial rhizobia and sanctioned non-fixing strains when extrinsic nitrogen was unavailable. Host benefits were undiminished when inoculated with rhizobia bearing nitrogen metabolism knockouts, suggesting redundancies in nitrogen provisioning systems. However, under nitrogen fertilization hosts did ..., Sole nitrogen source fertilization experiment 
The L. japonicus ecotype Miyakojima MG-20 was used, inbred at the University of California Riverside to generate seeds following published protocols. The M. loti genotype MAFF303099 (hereafter MAFF) is a highly effective nitrogen fixing strain on L. japonicus. MAFF was modified to express dsRed, a red fluorescent protein visible under natural light. The near-isogenic strain STM6 (strain ID 17T02d02) was employed as a non-nitrogen fixing mutant. STM6 was generated by a signature tagged transposon inserted in the nifD gene, and was subsequently modified to express GFP. Both modified strains efficiently form nodules on L. japonicus, with MAFF providing substantial benefits to host growth while STM6 provides none. MAFF and STM6 were grown on agar plates with a modified arabinose gluconate medium (MAG). In mixed cultures, MAFF and STM6 can be easily differentiated by colony color. Other than differences in nitrogen fixation and colony ..., # Nitrogen fertilization nullifies host sanctions against non-fixing rhizobia and drives divestment from symbiosis in Lotus japonicus

Dataset DOI: [10.5061/dryad.xksn02vtc](https://datadryad.org/submission/10.5061/dryad.xksn02vtc)

## Description of the data and file structure

**Nitrogen fertilization nullifies host sanctions against non-fixing rhizobia and drives divestment from symbiosis in *Lotus japonicus***

### Host Biomass data

* Plant_ID: Unique identifier for the focal plant (includes block number followed by the plant replicate number)
* Block: Block in which the focal plant was grown within the greenhouse
* Strain_Treatment: Category of strain (or strains) to which the focal plant was assigned; Fix+ = the nitrogen fixing strain MAFF303099; Fix- = the near isogenic non-fixing mutant STM6l; Coinoculant = co-inoculation with strains both strains; No Inocula = inoculation with sterile water
* Modified_Strain_Treatment: Same as above, but changes categories of plants that did n...,