Long-term fertilization shapes root rot resistance in Apocynum venetum through coordinated physiological and transcriptomic reprogramming

Fertilization affects not only plant growth but also the development of soil-borne diseases. However, how fertilization regimes that combine organic and inorganic inputs across vegetative and reproductive stages regulate root rot resistance in Apocynum venetum , a medicinal and fiber crop, remains unclear. In this study, we evaluated the effects of these fertilization treatments on growth and root rot in field-grown A. venetum by integrating physiological, hormonal, and transcriptomic analyses. Organic fertilization promoted plant growth while reducing disease incidence and severity, whereas mineral nitrogen-phosphorus fertilization exacerbated disease. Although both fertilizer types stimulated growth, they differentially regulated plant defense systems: mineral fertilization increased polyphenol oxidase and peroxidase activities, and salicylic acid (SA) accumulation, indicating a shift toward SA-mediated responses, whereas organic-based regimes maintained higher superoxide dismutase and catalase activities, flavonoid levels, and jasmonic acid (JA) accumulation, consistent with enhanced antioxidant capacity and JA-associated defenses. WGCNA identified key co-expression modules and hub genes linked to disease-related traits, revealing fertilization treatment-specific transcriptional networks. These findings indicate that fertilization-mediated variation in root rot is associated with coordinated changes in defense physiology and gene regulation, with organic and mineral fertilization differentially modulating immune and antioxidant systems despite their comparable growth-promoting effects. Together, these results provide a basis for optimizing fertilization strategies for sustainable disease management.