Rational Design of Phytovirucide that Inhibits the Nucleocapsid Condensates of Tomato Spotted Wilt Virus

Abstract Chemical management of crop failures caused by plant viruses poses serious challenges in agricultural chemistry. Recently, phase separation has emerged as a key role in the viral lifecycle, with the discovery of corresponding small molecule inhibitors in the medical field sparking significant interest. However, the applicability of this promising antiviral tactic for plant protection remains largely unknown. Herein, we have demonstrated that the aggregation of the tomato spotted wilt virus (TSWV) nucleocapsid protein (N) is regulated by RNA-induced phase separation, and disclosed a new rationally designed inhibitor Z9. Z9 is capable of binding to TSWV N at the R⁹⁴ and Y¹⁸⁴ sites, preventing the assembly of N and RNA into aggregated ribonucleoproteins through phase separation. Mutations of the binding sites substantially diminish the colocalization between N protein and processing bodies, interfering with the normal interaction of N protein with RNA. This study provides opportunities to phase separation-based anti-plant virus strategies.