The GTE7-IES2B-GTE2 complex epigenetically regulates sulfur homeostasis in Arabidopsis thaliana.

Maintaining sulfur (S) homeostasis is critical for plant growth and development, yet mechanisms regulating sulfate uptake remain poorly understood. We identify Global Transcription Factor Group E proteins, GTE7 and GTE2, along with the chromatin remodeling factor INO80 Subunit 2B (IES2B), as key regulators of S homeostasis in Arabidopsis thaliana. GTE7 directly binds to the Sulfur Response Element (SURE) in the promoter of the sulfate transporter gene SULTR1;1. The SURE flanking sequence undergoes dynamic DNA methylation in response to S status, with hypermethylation under S-sufficient conditions and hypomethylation under S-deficient conditions. GTE7 and its homolog GTE2 exhibit functional redundancy in suppressing sulfate accumulation in shoots. The gte7 gte2 double mutants displayed increased sulfate accumulation in shoots and impaired root growth. IES2B, a subunit of the INO80 chromatin remodeling complex, interacts with both GTE7 and GTE2, forming a regulatory complex that modulates dynamic DNA methylation at the SULTR1;1 promoter. Disruption of IES2B abolished S-resupply-induced DNA remethylation and elevated sulfate accumulation in shoots. Our findings reveal a GTE7-IES2B-GTE2 module that likely integrates transcriptional regulation and dynamic DNA methylation to fine-tune sulfate homeostasis, providing insights into the complex network of transcriptional and epigenetic regulation in response to S availability.