Mol Plant Microbe Interact. 2013 Jun 7

Carbonell A, Maliogka VI, Pérez JD, Salvador Esteban B, San León D, Garcia JA, Simón-Mateo C.

PPV-D and PPV-R are two isolates from strain D of Plum pox virus (PPV) that differ in host specificity. Previous analyses of chimeras originating from PPV-R and PPV-D suggested that the N-terminus of the coat protein (CP) includes host specific pathogenicity determinants.

Here, these determinants were mapped precisely by analyzing the infectivity in herbaceous and woody species of chimeras containing a fragment of the 3’ region of PPV-D –including the region coding for the CP– in a PPV-R backbone. These chimeras were not infectious in Prunus persica, but systemically infected Nicotiana clevelandii and Nicotiana benthamiana when specific amino acids (aa) were modified or deleted in a short 30-aa region of the N-terminus of the CP. Most of these mutations did not reduce PPV fitness in Prunus although others impaired systemic infection in this host.

We propose a model in which the N-terminus of the CP, highly relevant for virus systemic movement, is targeted by a host defense mechanism in Nicotiana. Mutations in this short region allow PPV to overcome the defense response in this host but can compromise the efficiency of PPV systemic movement in other hosts such as Prunus.