Ethylene-REF6 regulatory module enables endophyte-mediated thermotolerance of plant growth and reproduction

Global warming affects plant growth and yield, posing a major threat to global food security. Male sexual reproduction is the most sensitive stage for plant yield under elevated temperature (eT). We show here that under eT conditions, plant growth and male reproduction depend on the ethylene-mediated activity of the histone demethylase REF6. Although eT-compromised plant performance of wild-type plants can be fortified by treatment with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), ref6 mutant plants are insensitive to ACC, showing that ethylene-dependent eT-induced genes depend on REF6 histone demethylase activity. Sexual reproduction and yield, including pollen viability and germination, are strongly compromised in ethylene and ref6 mutants under eT conditions. Intriguingly, we demonstrate that the bacterial endophyte Enterobacter sp. SA187 deploys ethylene-mediated REF6 to protect plant growth and reproduction to eT. These results show that microbiome-assisted approaches can help to ensure food safety under changing climate conditions.