Targeting ParPMC Susceptibility Hubs in Prunus: eEF1A as a Conserved Mediator of Plum Pox Virus Infection in Nicotiana benthamiana

Abstract

[EN] Sharka, caused by Potyvirus plumpoxi (plum pox virus, PPV), is the most destructive viral disease affecting Prunus species worldwide. Two MATH domain-containing genes, ParPMC1 and ParPMC2, have been identified in apricot as host susceptibility factors required for PPV infection, but their molecular function remains unclear. Here, we investigated ParPMC functions by identifying their interacting partners and assessing their contribution to viral replication and movement. Yeast two-hybrid screening of PPV-infected apricot tissues revealed 13 ParPMC interactors involved in defence and stress responses, primary metabolism, protein folding and gene expression. Among them, two eukaryotic elongation factor 1-alpha proteins (eEF1A; Pruar1 and Pruar9) were selected for further analysis. In planta assays showed that both ParPMC proteins colocalize with eEF1A at endoplasmic reticulum-derived perinuclear structures associated with viral replication complexes; however, a specific physical interaction was detected only for ParPMC1, suggesting paralog specialisation. Phylogenetic analyses revealed independent diversification of eEF1A gene families in Rosaceae and Solanaceae. Despite the lack of strict orthology, silencing clade B eEF1A isoforms in Nicotiana benthamiana using a cucumber mosaic virus-based virus-induced gene silencing system strongly reduced PPV accumulation and systemic spread, highlighting a conserved proviral role. These results support a model in which ParPMC1 facilitates PPV infection by recruiting or stabilising eEF1A at viral replication sites, whereas ParPMC2 may contribute through alternative interactors. This study advances our understanding of ParPMC-mediated PPV-susceptibility in apricot and highlights host-virus interactions with potential relevance for resistance strategies in Prunus and other potyvirus-susceptible crops.