Kroženje rastlinskih viromov: povezanost urbanega okolja, divjih in gojenih rastlin

Viruses are among the most important pathogens of plants, causing significant economic losses in crop production worldwide. Several plant viruses that emerged in past decades have caused devastating global epidemics in important crops. The mechanisms underlying their emergence are hypothesized to be highly influenced by ecological changes or intensive agronomical practices. On the other hand, many viruses have been discovered in recent years in wild plants (such as weeds, which were shown to be potential reservoirs of economically important plant viruses), without obvious pathogenic effects on their hosts. The potential they might have as emergent pathogens of crop species is unclear, mainly due to the little knowledge about the cycling of plant viruses between the different habitats within an ecosystem. Such exchange of plant viruses, between different plant species and different fractions of an ecosystem, is likely to occur and can result in an emergence of a new pathogen. At the same time, in the context of viral ecology, the presence and stability of viruses in the environment and their potential spread to different, spatially distinct, habitats is also understudied. In our recent study, we have demonstrated that infective pathogenic plant viruses are released from urban environment into the environment (recipient river) through wastewater. However, little is known about other possible fluxes of plant viruses in the ecosystem; e.g., between water and aquatic and terrestrial plants, crop plants. Here, we aim to elucidate to which extent such cycling exists within a fragmented antropogenic landscape, consisting of urban influences, wild vegetation and agricultural production sites. To approach this aim, we will establish a sampling polygon including different parts within the fragmented anthropogenic landscape: a wastewater treatment plant (WWTP; representing the contribution of viruses from human, industrial and agricultural waste), a river receiving treated wastewater, wild aquatic and bank river vegetation at different locations relative to WWTP, and a proximal crop farm. We will perform systematic samplings of wild and crop plants and water at different locations and at several time points through two growing seasons. Using shotgun high-throughput sequencing (HTS) we will determine the viromes of collected samples (WP1). Based on the virome data for different parts of the ecosystem, different host species, and different time points, we will construct bipartite networks representing the relationships between viruses, hosts and habitats. Using network analysis approaches, we will determine the structure of such networks (e.g., nestedness vs modularity), most important connections (e.g., virus species linking several connected habitats) and possibly reveal any hidden links (WP2). In parallel, in WP3, we will, by using large-scale greenhouse plant infectivity assays, determine the potential of virus species discovered in wild plants (aquatic and terrestrial) in WP1 to infect and cause disease in crop plants. To further study the virus infection of aquatic plants, we will establish a system for their inoculation in controlled laboratory conditions and perform infectivity assays with selected viruses obtained in WP1. The results of this research project will provide innovative results about the observed and potential flux of plant viruses between different parts of a fragmented anthropogenic landscape. They will bring important basic data contributing to the understanding of the epidemiology of plant viruses in a fragmented ecosystem, such as pinpointing important plant virus species connecting different habitats. This will ultimately enable better understanding of the mechanisms of virus-caused plant disease emergence and its distribution in an ecosystem. Such data will have an important value for understanding the risks connected with agricultural, nature conservation and water regulatory practices within the ecosystem.