A Nitrate Transporter OsNPF6.1 Promotes Nitric Oxide Signaling and Virus Resistance.

Nitric oxide (NO) is a vital immune molecule eliciting resistance to diverse microbial pathogens in humans and animals. However, its functional integration into plant immune networks remains incompletely characterized. In this study, we reveal that both endogenous induction and exogenous supplementation of NO significantly enhance resistance to rice stripe virus (RSV), a Bunyavirus that poses a huge threat to rice production. The nitrate transporter OsNPF6.1 potentiates virus resistance by upregulating the expression of nitrate reductase (OsNR2) and subsequent NO biosynthesis. Functional analyses demonstrate that the disease-specific protein (SP) encoded by RSV interacts with OsNPF6.1 to impair its nitrate transport activity, effectively subverting host immunity to facilitate RSV infection. Notably, this host-pathogen interaction exhibits nitrogen dependency: low nitrate availability attenuates the OsNPF6.1-SP association, preserving transporter functionality and virus resistance. Thus, this study not only provides novel insights into the coordination of growth-defense tradeoffs but also proposes actionable strategies for crop protection via optimized nitrogen management.