The Effects of Gene Function of Endophytic Fungus OW7.8 on Swainsonine Biosynthesis.

Locoweeds, including and species, are globally recognized as plants containing swainsonine (SW), a neurotoxic alkaloid that induces neurological dysfunction and growth inhibition in livestock. SW is produced by endophytic fungi in plants; the pyrroline-5-carboxylate reductase (P5CR) gene is critical in the fungal SW biosynthetic pathway. In this study, a gene knockout mutant (Δ) was constructed from the endophytic fungus OW7.8 isolated from . Compared to the wild-type strain ( OW7.8), the SW content in the Δ mycelia was significantly reduced, indicating that the P5CR gene plays a crucial role in promoting SW biosynthesis. Compared to the wild-type strain OW7.8, the Δ mutant exhibited distinct morphological alterations in both colony and mycelial structures. The transcriptomic analysis of OW7.8 and Δ revealed the downregulation of six genes associated with SW biosynthesis. Metabolomic profiling further demonstrated altered levels of six metabolites linked to SW synthesis. These findings provide foundational insights into the molecular mechanisms and metabolic pathways underlying SW biosynthesis in fungi. They hold significant value for future strategies to control SW in and contribute positively to the protection and sustainable development of grassland ecosystems.