Design and synthesis of N ‐heterocycle‐fused azolyl selenoureas against Rhizoctonia solani and its mode‐of‐action

Abstract BACKGROUND Rhizoctonia solani , a deleterious fungal pathogen, significantly impedes global crop productivity. This investigation focused on designing and synthesizing novel N ‐heterocycle‐fused azolyl selenoureas to assess their antifungal efficacy and molecular mode‐of‐action against R. solani . RESULTS A series of N ‐heterocycle‐fused azolyl selenoureas were synthesized. Most compounds demonstrated significant antifungal activity (median effective concentration 2.3–13.4 mg L −1 ). Compound 2 exhibited potent in vitro and in vivo efficacy. Its curative and protective effects on detached rice leaves were concentration‐dependent, with maximal efficacy at 100 mg L −1 (80.8 and 81.2%, respectively) exceeding azoxystrobin. Notably, it substantially inhibited sclerotial germination (45.3% at 6.25 mg L −1 ). Mechanistic investigations revealed severe disruption of hyphal tissue structure, and increased membrane permeability and cytoplasmic leakage, resulting in cellular mortality. Additionally, it induced reactive oxygen species generation, dissipated mitochondrial membrane potential and reduced nuclear count. Transcriptomic analysis demonstrated significant downregulation of MCM2‐7 and PCNA genes associated with DNA replication pathways. CONCLUSION N ‐heterocycle‐fused azolyl selenoureas, particularly compound 2 , demonstrate potential as multimechanistic agents for R. solani management in agricultural pathology. © 2025 Society of Chemical Industry.