The Potyvirus genus is one of the largest genera of plant RNA viruses responsible for serious diseases in vegetable and fruit crops worldwide [1]. As potyviruses have developed strategies to hijack the host secretory pathway and plasmodesmata (PD) for their transport, the goal of this study was to identify membrane and/or PD-proteins that interact with one of the viral proteins involved in the cell-to-cell movement of turnip mosaic virus (TuMV) the “second 6 kDa molecular-weight membrane anchoring protein” (6K2). The 6K2 induces the formation of endoplasmic reticulum (ER)-derived viral vesicles, important not only for replication but also for intra- and intercellular movement of TuMV [2]. In Arabidopsis thaliana, AtHVA22a (Hordeum vulgare abscisic acid responsive gene 22) belongs to a multigenic family of transmembrane proteins, homologous to DP1/Yop1 family proteins in yeast and interactors of reticulons, which are responsible for the constriction of ER tubules. The role of HVA22 gene family has been poorly studied in plants, even if its potential involvement in response to abiotic stresses was highlighted [4]. Recent proteomics analysis of PD fractions purified from Arabidopsis thaliana suspension cells showed that AtHVA22a is highly enriched in plasmodesmata proteome [3]. Here, using a Split-ubiquitin membrane Y2H assay we screened an Arabidopsis cDNA library and identified AtHVA22a as an interactor of the 6K2 protein of TuMV. We further confirmed this interaction in yeast and in planta using bimolecular fluorescence complementation (BiFC) and showed that the 6K2/AtHVA22a interaction occurs at the level of the viral replication complexes during TuMV infection and partially at PD levels. Furthermore, overexpression of AtHVA22a increases TuMV propagation in Nicotiana benthamiana while TuMV propagation is slowed down in AtHVA22a-CRISPR/Cas9 mutants. Altogether, our results indicate that AtHVA22a plays an agonistic effect on TuMV propagation.[1] doi:10.1099/jgv.0.000740. [2] doi:10.3389/fmicb.2013.00351. [3] doi:10.15252/embr.201847182. [4] DOI: 10.1023/a:1015593715144Read less <