The JmjC domain-containing histone demethylase ZmJMJ703 orchestrates salt stress adaptation in maize

Abstract

The JmjC domain-containing protein family (JMJs) represents a family of key demethylases critical for epigenetic regulation and orchestrating plant growth and developmental processes. Despite their established roles, functional investigations into JMJ proteins under abiotic stress conditions remain limited in maize. In this study, we identified and functionally characterized ZmJMJ703, a JmjC domain-containing gene exhibiting salt stress-responsive expression patterns in maize. Physiological and phenotypic analysis revealed that ZmJMJ703 mutation significantly impairs salt stress tolerance in maize seedlings. Transcriptomic profiling uncovered differential expression patterns between zmjmj703 mutants and wild-type plants, with affected genes predominantly associated with intracellular protein trafficking, amino acid metabolism, and small molecule reprogramming. Parallel proteomic analysis through mass spectrometry further demonstrated that differential protein accumulation in mutants primarily enriched pathways related to secondary metabolite biosynthesis. These integrated omics analyses collectively suggest that ZmJMJ703 may modulate metabolic pathways critical for abiotic stress responses. Functional validation was reinforced by phenotypic evaluation of Arabidopsis lines heterologous overexpressing ZmJMJ703, which exhibited enhanced salt stress tolerance compared to control plants. Collectively, these findings significantly advance our mechanistic understanding of JMJ proteins' contributions to plant abiotic stress resilience, particularly in the context of salt stress adaptation.