Rhizosphere microorganisms can influence the timing of plant flowering

[Background]: Plant phenology has crucial biological, physical, and chemical effects on the biosphere. Phenological drivers have largely been studied, but the role of plant microbiota, particularly rhizosphere microbiota, has not been considered.[Results]: We discovered that rhizosphere microbial communities could modulate the timing of flowering of Arabidopsis thaliana. Rhizosphere microorganisms that increased and prolonged N bioavailability by nitrification delayed flowering by converting tryptophan to the phytohormone indole acetic acid (IAA), thus downregulating genes that trigger flowering, and stimulating further plant growth. The addition of IAA to hydroponic cultures confirmed this metabolic network.[Conclusions]: We document a novel metabolic network in which soil microbiota influenced plant flowering time, thus shedding light on the key role of soil microbiota on plant functioning. This opens up multiple opportunities for application, from helping to mitigate some of the effects of climate change and environmental stress on plants (e.g. abnormal temperature variation, drought, salinity) to manipulating plant characteristics using microbial inocula to increase crop potential.This work was financially supported by the National Natural Science Foundation of China (21577128, 21777144), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB15020302 and XDB15020402), the CAS Pioneer Hundred Talents Program (H.F. Qian), and the Xingjiang Uighur Autonomous Region Talent Project (H.F. Qian). JP research is funded by the European Research Council Synergy grant SyG-2013-610028 IMBALANCE-P.Peer reviewe