Rice Fatty Acid Desaturase OsFAD6 Confers Antiviral Resistance against RBSDV through MAPK and Hormone Signaling

Fatty acids (FAs) are crucial for plant defense against pathogens. While unsaturated fatty acids (UFAs), synthesized by fatty acid desaturases (FADs), are established mediators of resistance against bacterial and fungal pathogens, their involvement in regulating virus infection remains poorly understood. Here, we demonstrate that OsFAD6, a chloroplast-localized fatty acid desaturase, confers resistance to rice black-streaked dwarf virus (RBSDV). RBSDV infection significantly suppresses OsFAD6 expression, suggesting viral targeting of this defense component. Functional analyses using OsFAD6-overexpressing and knockout rice lines established that OsFAD6 enhances resistance to RBSDV. Transcriptomic profiling revealed that OsFAD6 enhances antiviral defense through modulation of the MAPK signaling cascade and reprogramming of multiple hormone signaling pathway-associated genes. Furthermore, OsFAD6 can be degraded by RBSDV P5–2 through the autophagy pathway. These findings identify OsFAD6 as a novel antiviral component in rice and provide new molecular targets for breeding virus-resistant rice varieties.