Metabolomics dataset for disentangling plant and environment-mediated drivers of active rhizosphere 1 bacterial community dynamics during short-term drought

Background: Mitigating the effects of climate stress on crops is important
for global food security. The microbiome associated with plant roots,
henceforth, the rhizobiome, can harbor beneficial microbes that alleviate
stress impacts. However, the factors influencing the recruitment of the
rhizobiome during stress are unclear. We conducted an experiment to
understand bacterial rhizobiome responses to short-term drought for two
crop species: switchgrass and common bean. We used 16S rRNA and 16S rRNA
gene sequencing to investigate the impact of drought severity on the
recruitment of active bacterial rhizobiome members. We included planted
and unplanted conditions to distinguish the environment- versus plant
mediated drivers of the active rhizobiome. Results: Though each crop had a
distinct rhizobiome, there were differences in the active microbiome
structure between drought and watered and between planted and unplanted
treatments. Despite their different community structures, the drought
rhizobiome dynamics were similar across the two crops. However, the
presence of a plant more strongly explained the rhizobiome variation in
bean (17%) than in switchgrass (3%), with a small effect of plant
mediation during drought only observed for the bean rhizobiome. The
switchgrass rhizobiome was stable despite differences in the rhizosphere
metabolite profiles between planted and unplanted treatments.
Specifically, steroidal saponins and diterpennoids were enriched in
drought, planted switchgrass soils. Conclusions: We conclude that
rhizobiome benefits to resist short-term drought are crop-specific, with
the possibility of decoupling of plant exudation and rhizobiome responses,
as we observed in switchgrass. We propose bacterial taxa uniquely
associated with common bean plants during the short-term drought, which
could be further evaluated to determine any plant benefit during drought.