Quantitative resistance to Plum pox virus in Prunus davidiana P1908 linked to components of the eukaryotic translation initiation complex

A complex, polygenic resistance to Plum pox virus (PPV) was previously described in a wild peach-related species, Prunus davidiana clone P1908. In the current study, an analysis of quantitative trait loci (QTL) was performed on an F₂ population comprising 99 individuals obtained by selfing the F₁ individual #40 of an interspecific cross between susceptible nectarine cv. Summergrand and the resistant P. davidiana clone P1908. Six QTL were identified using both parametric and non-parametric methods of detection, individually explaining 5–28% of the phenotypic variance. The total phenotypic variation explained ranged from 29 to 58%. Alignment of the genetic map of the F₂ cross with the P. davidiana parent map showed consistency of QTL over generations, with three of the six QTL co-localizing at the 1-LOD interval and another one at the 2-LOD interval. Two of the QTL were mapped onto linkage group one, where resistance to PPV was previously mapped in apricot. Development and mapping of new microsatellite markers linked to candidate genes revealed a striking co-localization of three of the detected QTL with gene copies coding for eukaryotic translation initiation factors eIF4E and eIF(iso)4G. As co-localization of one QTL with candidate gene eIF(iso)4E was previously reported in the F₁ population, the results reported here strongly reinforce the idea that components of the eukaryotic translation initiation complex are correlated with resistance to PPV in P. davidiana P1908.