The coat protein determines the specificity of virus transmission by xiphinema diversicaudatum
A. Marmonier, P. Schellenberger, D. Esmenjaud, C. Schmitt-Keichinger, C. Ritzenthaler, P. Andret-Link, O. Lemaire, M. Fuchs, G. Demangeat
Arabis mosaic virus (ArMV) and Grapevine fanleaf virus (GFLV), two closely related members of the genus Nepovirus, family Secoviridae, are responsible for fanleaf degeneration disease of grapevines. ArMV and GFLV are specifically transmitted by the ectoparasitic soilborne nematodes Xiphinema diversicaudatum and X. index, respectively. Previous work has shown that the coat protein determines the transmission specificity of GFLV. No information is available on the determinants of the specific transmission of ArMV by X. diversicaudatum. We addressed this issue by testing the transmissibility of three chimeric viruses comprising GFLV RNA-1 and GFLV/ArMV chimeric RNA-2 molecules coding for a coat protein from ArMV. The three recombinant viruses and wild type ArMV, unlike GFLV, were transmitted by X. diversicaudatum but not by X. index. In addition, RT-PCR assays indicated that ArMV and the three chimeric viruses seemed to be retained by X. diversicaudatum but not by X. index following nematode feeding on infected plants. Conversely, GFLV was retained by X. index but not by X. diversicaudatum. These results are consistent with the notion that the coat protein carries the determinants for the specific transmission of Ar- MV by X. diversicaudatum and that transmission specificity of both ArMV and GFLV is associated with specific virus retention by nematode vectors.