Despite its importance, our understanding of how viruses evolve into new species is still limited. The PLANTVIRSPE (Analysis of speciation modes in plant RNA viruses) project addressed this knowledge gap by investigating virus speciation based on the interactions between plants and viruses. Project partners focused on the genus Potyvirus, which infect wild hosts in evergreen oak and riparian forests, two of the most widespread ecosystems in the European Mediterranean Basin. The genetic diversity and structure of Potyvirus was studied in the selected ecosystems together with the ecological factors that influence speciation. Scientists also developed a predictive model. Potyvirus was collected and characterised from five evergreen oak locations and five riparian forest locations in the Iberian Peninsula. Researchers drew up a list of the plant diversity at each location and identified the Potyvirus species – their occurrence and the hosts range were then determined. Results showed that plant composition and host species richness differed between the two ecosystems, being higher in riparian forests. Furthermore, the occurrence of Potyvirus and virus species richness was also higher in riparian forests. The two ecosystems featured different species of viruses, some of which had not been previously reported, indicating that the likelihood of Potyvirus infection was greater in systems with higher biodiversity. Nucleotide sequences of the protein coat gene were obtained for 157 virus isolates from the two ecosystems and compared using genomic analyses. This revealed that the genetic diversity of potyvirus populations was influenced by the host and geographical location of each sampled virus isolate. Analysis based on the multivariate predictive model showed that biodiversity and plant densities, together with climatic factors, were the main factors affecting the occurrence of Potyvirus and genetic diversification. PLANTVIRSPE provided a vital contribution to understanding how new plant viruses evolve, enabling scientists to design better strategies for combatting the emergence of new infectious diseases and for controlling existing ones.
Genetic diversity, PLANTVIRSPE, speciation, Potyvirus, nucleotide sequences