Temperature-induced DNA methylation controls wood fiber wall development through the SsuMYB295–SsuTDX module in Schima superba

Although wood fiber structure critically determines wood quality in the economically vital tree species Schima superba , the regulatory network underpinning its geographic variation remains elusive. Here, through comprehensive sampling across the species’ natural range, we revealed pronounced provenance-level divergence in wood fiber characteristics, which strongly co-varied with the expression of the SsuTDX tandem gene cluster ( p < 0.01). Mechanistically, although the transcription factor SsuMYB295 positively regulates all three SsuTDX units, hypermethylation in the promoter of the third unit severely hinders SsuMYB295 binding. This gene-unit-specific epigenetic silencing drives expression variation among cluster members and mirrors geographic traits in fiber morphology. importantly, methylation level is tightly linked to local temperature regimes, uncovering an environmental-epigenetic temperature–methylation–SsuMYB295– SsuTDX regulatory axis. Our study provides mechanistic insights to inform precision breeding for enhanced wood quality in S. superba .