Identified a new plant virus species native of evergreen oak forests of the Iberian Peninsula and the factors associated with its incidence and population genetic diversity

Since the discovery of the first plant virus more than a century ago, the study of any aspect of plant-virus interactions has been motivated by the agro-economic impact of the detrimental effects of virus infection in crops. Thus, very little is known on the diversity of plant viruses, and the consequences of their infections, in wild hosts. Moreover, studies on the factors determining the prevalence and population genetic diversity of these viruses are remarkably scant. Addressing these questions is important for the Biology of Conservation, as virus infection may have a negative impact on their wild host populations. Indeed, in extreme cases virus infection may lead to the local extinction of the host plant, with the subsequent reduction of ecosystem biodiversity. In addition, wild ecosystems are frequently adjacent to agroecosystems, which facilitates virus dispersal into crops and increases the risk of epidemics. Dr. Pagán´s group has analyzed for three years the prevalence and the diversity of viruses from the Potyvirus genus, which account for 20% of all known plant viruses, in evergreen oak forests of the Iberian Peninsula, the most frequent wild ecosystem in the Mediterranean basin. This study has identified a new virus that infects a plant species typical of evergreen oak forests: mountain rue (Ruta montana L.), and for which the name Mediterranean ruda virus (MeRV) has been proposed. Using this virus as a model, Dr. Pagán´s group has analyzed whether ecological factors such as ecosystem´s plant species diversity and biomass, host density, temperature, relative humidity and rainfalls are determinants of MeRV prevalence and population genetic diversity. The main predictor of MeRV prevalence was host density, whereas the main ecological factor affecting MeRV population genetic diversity was virus prevalence. Although the only identified MeRV wild host was mountain rue, the virus infected pepper and tomato in greenhouse conditions. However, Dr. Pagán´s group did not detect MeRV in pepper and tomato fields located near the evergreen oak forests where MeRV is present. This suggests that the risk of MeRV emergence in these crops is low. In summary, this work contributes to the understanding of the diversity of virus species in wild ecosystems and of the ecological factors determining the prevalence and population genetic diversity of these viruses.