NIb Interaction Sites ³⁵⁹⁷AUU and ³⁶⁰⁷GGCU Are Crucial to the Replication of Wheat Yellow Mosaic Virus RNA2

Wheat yellow mosaic virus (WYMV) is the main cause of wheat yellow mosaic disease. Although its regulation of protein translation and interactions with host proteins are well-studied, independent regulation of the virus genome is poorly understood. This study performed in vitro experiments investigating replication regulation by the 5' UTR and 3' UTR of WYMV RNA2. The results confirm that the RNA-dependent RNA polymerase (NIb) can only recognize and catalyze the synthesis of 3' 190 nt complementary chains in vitro. RNA structure probing and mutation analysis identified 3597AUU and 3607GGCU as novel interaction sites of NIb; both are essential for maintaining normal replication. Our findings provide an empirical basis for in vivo experiments on regulation of WYMV genome replication and provide theoretical basis for the prevention and control of WYMV-related crop diseases.