[Dr. Na-Sheng Lin] Importin α2 participates in RNA interference against bamboo mosaic virus accumulation in Nicotiana benthamiana via NbAGO10a-mediated small RNA clearance

Importin α, a member of karyopherins, participate in multiple RNA silencing stages by transporting associated proteins into the nucleus. While plant RNA viruses typically replicate in the cytoplasm, the effects of importin α on plant RNA virus replication remains largely unknown. Unlike other RNA viruses, for which importin α facilitates virus infection via nuclear import of viral protein, research from Dr. Na-Sheng Lin’s group found that silencing of importin α2 (α2i) by virus-induced gene silencing (VIGS) boosted the titre of bamboo mosaic virus (BaMV) in Nicotiana benthamiana. The enhanced BaMV accumulation in importin α2i plants was linked to reduced levels of RDR6-dependent secondary virus-derived small-interfering RNAs (vsiRNAs). Deletion of BaMV TGBp1, an RNA silencing suppressor, compromised importin α2i-mediated BaMV enhancement. Moreover, silencing of importin α2 upregulated NbAGO10a, a proviral protein recruited by TGBp1 for BaMV vsiRNAs clearance, but hindered the nuclear import of NbAGO10a. Taken together, these results indicate that importin α2 acts as a negative regulator of BaMV invasion by controlling the expression and nucleocytoplasmic shuttling of NbAGO10a, which removes vsiRNAs via the TGBp1-NbAGO10a-SDN1 pathway.

Wang, Hsu, Lee, and Lin et al (2024). Importin α2 participates in RNA interference against bamboo mosaic virus accumulation in Nicotiana benthamiana via NbAGO10a-mediated small RNA clearance. Molecular Plant Pathology 25:e13422.