Rice black-streaked dwarf virus P10 induces membranous structures at the ER and elicits the unfolded protein response in Nicotiana benthamiana

- Rice black-streaked dwarf virus P10 forms ER membrane-associated structures.
- P10 contains multiple ER-targeting domains and a chloroplast-associated domain.
- The maintenance of P10-induced membrane structures requires an intact actin cytoskeleton.
- P10 elicits the ER stress and unfolded protein response.

Endoplasmic reticular (ER) membrane modifications play an important role in viral RNA replication and virion assembly but little is known about the involvement of ER-membrane remodeling in the infection cycle of fijiviruses in plant cells. The subcellular localization of Rice black-streaked dwarf virus outer capsid P10 was therefore examined using live-cell imaging. P10 fused to eGFP formed vesicular structures associated with ER membranes in Nicotiana benthamiana epidermal cells and in rice protoplasts. Subcellular fractionation experiments confirmed that P10 is an integral membrane protein. Three predicted transmembrane domains and two less-well-defined domains were each able to target eGFP to the ER. Disruption of the actin cytoskeleton with LatB, indicated that the maintenance of P10-induced membrane structures required the intact actin cytoskeleton. P10 induced the expression of ER stress marker genes, including ER stress-related chaperones and transcription factor, indicating that RBSDV P10 triggers ER stress and the unfolded protein response.