H3K4 demethylase SsJMJ11 negatively regulates drought-tolerance responses in sugarcane.

BACKGROUND: Drought-induced gene alteration is usually associated with changes of histone H3K4me3 in plants. Histone methylation homeostasis relies on the coordinated activity of methyltransferases and demethylases. We previously demonstrated that SsJMJ11 is an H3K4me3 demethylase in Saccharum spontaneum and participates in regulating flowering time. However, the role of H3K4me3 regulators in regulating drought-stress responses in sugarcane (Saccharum spp.) remains elusive. RESULTS: We show that SsJMJ11 negatively regulates drought-stress responses by acting as an H3K4me3 demethylase. Ectopic overexpression of SsJMJ11 in Arabidopsis thaliana resulted in a hypersensitivity to soil drought stress as well as abscisic acid (ABA) and mannitol. Meanwhile, the drought-induced expression of AtRD20 and AtDREB2A, two well-known positive regulators of drought tolerance, was repressed by SsJMJ11 overexpression. In S. spontaneum, the ABA- and dehydration-induced transcription of SsRD20 and SsDREB2A was associated with increased H3K4me3 levels at these loci. Furthermore, transient overexpression of SsJMJ11 in S. spontaneum protoplasts reduced the ABA-induced transcription of SsRD20 and SsDREB2A, paralleling reduced H3K4me3 levels at these loci. CONCLUSIONS: Our results suggest that SsJMJ11-mediated dynamic deposition of H3K4me3 is required for proper adaptation to drought stress in sugarcane.