Vozelj, A.; Povalej, T. M.; Stare, K.; Znidaric, M. T.; Bacnik, K.; Levak, V.; Aguirre, I. G.; Podobnik, M.; Gruden, K.; Coll, A.; Lukan, T.

Potato virus Y (PVY) is one of the top ten economically most important plant viruses and responsible for major yield losses. We previously suggested the involvement of the N terminal region of potato virus Y coat protein (CP) in PVY spread. By constructing different PVY N terminal deletion mutants, we here show that deletions of 40 or more amino acid residues from the N terminal region of the CP resulted in the PVY multiplication limited to primary infected cells. Deletion of 26 residues profoundly impaired PVY cell-to-cell movement and prevented systemic PVY spread, while deletions of 19-23 residues allowed delayed systemic PVY spread. Introduced point mutations in the identified region hinder the filaments formation (S21G) and prevent (S21G) or delay (G20P) PVY movement. In addition, the mutants with deletion of more than 23 residues were not able to form full length viral particles in bombarded leaves, which confirms the overall significance of this region also in capsid assembly.