DisplayTitle

Direct Interaction Between the Rice yellow mottle virus (RYMV) VPg and the Central Domain of the Rice eIF(iso)4G1 Factor Correlates with Rice Susceptibility and RYMV Virulence

¹UMR186 Résistance des Plantes aux Bio-agresseurs, Institut de Recherche pour le Développement BP 64501, 34394 Montpellier cedex 5, France; ²UMR5048 Centre de Biochimie Structurale, 29 rue de Navacelles, 34090 Montpellier, France; ³Institut de l'Environnement et de Recherches Agricoles (INERA), 01 BP 476, Ouagadougou, Burkina Faso; ⁴Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei 10617, Taiwan; ⁵UMR5096 Génome et Développement des Plantes, Université de Perpignan via Domitia–CNRS–IRD, BP 64501, 34394 Montpellier cedex 5, France

The adaptation of Rice yellow mottle virus (RYMV) to recessive resistance mediated by the rymv1-2 allele has been reported as a model to study the emergence and evolution of virulent variants. The resistance and virulence factors have been identified as eukaryotic translation initiation factor eIF(iso)4G1 and viral genome–linked protein (VPg), respectively, but the molecular mechanisms involved in their interaction are still unknown. In this study, we demonstrated a direct interaction between RYMV VPg and the central domain of rice eIF(iso)4G1 both in vitro, using recombinant proteins, and in vivo, using a yeast two-hybrid assay. Insertion of the E309K mutation in eIF(iso)4G1, conferring resistance in planta, strongly diminished the interaction with avirulent VPg. The efficiency of the major virulence mutations at restoring the interaction with the resistance protein was assessed. Our results explain the prevalence of virulence mutations fixed during experimental evolution studies and are consistent with the respective viral RNA accumulation levels of avirulent and virulent isolates. Our results also explain the origin of the residual multiplication of wild-type isolates in rymv1-2–resistant plants and the role of genetic context in the poor adaptability of the S2/S3 strain. Finally, the strategies of RYMV and members of family Potyviridae to overcome recessive resistance were compared.