Chromatin Remodeling Complex SWR1 Regulates Root Development by Affecting the Accumulation of Reactive Oxygen Species (ROS)

Reactive oxygen species (ROS), a type of oxygen monoelectronic reduction product, play integral roles in root growth and development. The epigenetic mechanism plays a critical role in gene transcription and expression; however, its regulation of ROS metabolism in root development is still limited. We found that the chromatin remodeling complex SWR1 regulates root length and lateral root formation in Arabidopsis. Our transcriptome results and gene ontology (GO) enrichment analysis showed that the oxidoreductase activity-related genes significantly changed in mutants for the Arabidopsis SWR1 complex components, such as arp6 and pie1, and histone variant H2A.Z triple mutant hta8 hta9 hta11. The three encoding genes in Arabidopsis are the three H2A.Z variants hta8, hta9, and hta11. Histochemical assays revealed that the SWR1 complex affects ROS accumulation in roots. Furthermore, chromatin immunoprecipitation quantitative real-time PCR (ChIP-qPCR) analysis showed that the reduced H2A.Z deposition in oxidoreductase activity-related genes caused ROS to accumulate in arp6, pie1, and hta8 hta9 hta11. H2A.Z deposition-deficient mutants decreased after the trimethylation of lysine 4 on histone H3 (H3K4me3) modifications and RNA polymerase II (Pol II) enrichment, and increased after the trimethylation of lysine 27 on histone H3 (H3K27me3) modifications, which may account for the expression change in oxidoreductase activity-related genes. In summary, our results revealed that the chromatin complex SWR1 regulates ROS accumulation in root development, highlighting the critical role of epigenetic mechanisms.