PVwide Organization

    One of our main projects which corresponds to the characterisation, at both molecular and biological levels, of new Potato Virus Y recombinant isolates. To date, the molecular data obtained from Potato Virus Y (PVY) detection/characterization studies showed that the PVY had evolved by mutation (acquisition of necrotic abilities) and recombination. The epidemiological data collected in Europe and in North-America revealed that recombinant variants (PVY^N-W and PVY^NTN), resulting from the recombination between “ancestral” PVY^N and PVY^O isolates, have recently emerged and became (during the last five years) majority within natural populations of PVY. Recent data collected in France (by our team), Germany (Schubert et al. 2007) and in USA (Lorenzen et al., 2006), described new PVY genomic organisations (neither YN-W nor Y^NTN) coming from original recombination(s) of PVY isolates. Then, this phenomenon (recombination events) seemed to significantly drive the evolution of viral populations of PVY. We suppose that the recombinant isolates described to date represent only a part of the evolutionary potential of the PVY genome. New isolates, not yet described and putatively more virulent/aggressive, could correspond to future emergence of new PVY variants. In consequence, it seems to be of great interest to be able to better estimate the genomic diversity of PVY and to understand the events having led to the diversity of the PVY observed to date. It will allow 1) evaluating the evolutionary potential of PVY, 2) predicting the future emergence of new isolates and their impact on main cultivated PVY hosts.

    The first step of this project is to use a powerful and original tool for the description of the genomic diversity of PVY genome. The SNaPShot technology used in our laboratory (Rolland et al., JVM, in press) will be optimize adding new Single Nucleotide Polymorphism (SNP) markers as targets in order to screen and analyze the entire PVY genome. The produced results will allow to refine the classification of PVY strains and to identify new recombinant isolates not characterized by molecular and/or serological tools used currently. The distribution of the SNPs along the PVY genome will allow highlighting genomic organizations that result of new recombination events in various host plants (potato, tobacco, weeds, etc.). Original isolates with particular molecular characteristics will have to be characterized for their biological properties (fitness and symptoms) on various hosts of agronomical interest. The collected data will allow the identification of the selective pressures that drive the evolution genome of PVY by recombination and the next emergence of new PVY isolates. This will allow pointing out the biotic and non biotic parameters that are in favour with PVY evolution by recombination towards more damageable PVY isolates.

    In this framework, we constituted an international network of collaborators who actively take part in the objectives of the research program  (1) by collecting a wide diversity of viral isolates coming from intensive prospection in their country and (2) by characterizing biological properties in their local experimental conditions of all isolates defined as relevant after molecular analyzes conducted in the team "Biology and evolution of RNA phytoviruses" in INRA in Rennes-LeRheu. The analyzes of the data produced by all the members of our active network will allow to understand the diversity of viral genome in all the world.