Antifungal terpenoids from Neopallasia pectinata and in vivo activity of 4‐terpineol against rice sheath blight

BACKGROUND: Oryza sativa L. (rice) sheath blight, caused by Rhizoctonia solani Kühn, is a major disease threatening rice production. This study identifies antifungal constituents from Neopallasia pectinata (Pall.) Poljakov and characterizes 4-terpineol against R. solani using in vitro, in vivo, and mechanistic approaches. Transcriptomic and physiological analyses showed impaired membrane integrity and extensive remodeling of sterol and fatty-acid metabolism, accompanied by strong Pleiotropic Drug Resistance (PDR)-associated responses. 4-Terpineol also perturbed mitochondrial membrane-potential homeostasis and induced glutathione- and glutathione S-transferase-associated responses without detectable reactive oxygen species accumulation under the tested conditions. CONCLUSION: 4-Terpineol induces membrane-associated disturbance and extensive adaptive responses in R. solani. Its in planta activity, practical availability from alternative sources, and chemically modifiable structure support its potential as a natural-product-derived lead scaffold for further optimization against rice sheath blight.