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bioRxiv · 10.1101/2020.11.06.371146

Microbiota-root-shoot axis modulation by MYC2 favours Arabidopsis growth over defence under suboptimal light

Hou, S.·Thiergart, T.·Vannier, N.·Mesny, F.·Ziegler, J.·Pickel, B.·Hacquard, S.
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Abstract

Bidirectional root-shoot signalling is likely key in orchestrating stress responses and ensuring plant survival. Here we show that Arabidopsis thaliana responses to microbial root commensals and light are interconnected along a microbiota-root-shoot axis. Microbiota and light manipulation experiments in a gnotobiotic system reveal that low photosynthetically active radiation (LP) perceived by leaves induce long-distance modulation of root bacterial, but not fungal or oomycetal communities. Reciprocally, bacterial root commensals and particularly Pseudomomas isolates are necessary for rescuing plant growth under LP. RNA-Seq, combined with leaf inoculation experiments with biotrophic and necrotrophic microbial pathogens indicate that microbiota-induced growth under LP coincides with transcriptional repression of immune responses, thereby increasing susceptibility to both pathogens. Inspection of a set of A. thaliana mutants demonstrates that orchestration of this light-dependent growth-defence trade-off requires the transcriptional regulator MYC2. Our work indicates that aboveground stress responses in plants can be governed by signals from microbial root commensals.

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Hou, S., Thiergart, T., Vannier, N., Mesny, F., Ziegler, J., Pickel, B., Hacquard, S.. 2020-11-08. Microbiota-root-shoot axis modulation by MYC2 favours Arabidopsis growth over defence under suboptimal light. https://doi.org/10.1101/2020.11.06.371146

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