DUFB Promotes Broad-Spectrum Disease Resistance by Stabilizing GS1;1 in Rice

Abstract Excessive nitrogen (N) fertilization increases rice susceptibility to pathogens, yet the molecular links between N signaling and immunity remain largely unresolved. In this study, we identified three genes encoding DUF-domain-containing proteins, DUFA, DUFB, and DUFC, which were induced by Rhizoctonia solani (R. solani) infection and N treatment. Analyses of dufa/b/c mutant and overexpression lines showed that DUFA/B/C genes have functional redundancy and confer broad-spectrum resistance to sheath blight (ShB), blast, and bacterial blight. DUFA/B/C interacted with glutamine synthetase 1;1 (GS1;1), suggesting that distinct DUF proteins may converge on a shared GS1;1-associated defense pathway. Subsequent analyses demonstrated that DUFs enhance rice ShB resistance by inhibiting ubiquitin-mediated GS1;1 degradation. The GS1;1 protein level was reduced in high-nitrogen (HN) compared to in low-nitrogen (LN) conditions, implying that DUFB-GS1;1 signaling might be involved in N-dependent rice disease resistance. Overall, these findings reveal a mechanism linking the N status to rice immunity through DUFB-mediated stabilization of GS1;1.