Data from: Switchgrass rhizosphere metabolite chemistry driven by nitrogen availability

Plants and soil microorganisms interact closely in the rhizosphere where
plants may exchange carbon (C) for functional benefits from the microbial
community. For example, the bioenergy crop, switchgrass (Panicum virgatum)
is thought to exchange root-exuded C for nitrogen (N) fixed by diazotrophs
(free-living N-fixers). However, this interaction is not well
characterized and it is not known how or if switchgrass responds to
diazotrophs or their activity. To explore this question, we assessed
rhizosphere metabolite chemistry of switchgrass grown in a hydroponic
system under two N levels and under inoculated or uninoculated conditions.
Plants were grown with the inoculum Azotobacter vinelandii DJ for three
days before harvest. We found switchgrass root exudate chemistry to be
driven by N availability. Total metabolite concentrations were generally
greater under high N versus low N and unaffected by inoculation.
Examination of rhizosphere chemical fingerprints indicates metabolite
chemistry was also driven strongly by N availability with a greater
relative abundance of carbohydrates under high N and greater relative
abundance of organic acids under low N. We also found evidence of changes
in rhizosphere chemical fingerprints by inoculation treatment. However, we
found little evidence of N treatment and inoculation interaction effects
which suggests this response is not directly mediated by N availability.