What are the roles of plant viruses in natural settings? Do they evolve differently in nature than cultivated environment?

Many plant viruses in natural settings have less influence in plant fitness. Most of them are less pathogenic or at least not harmful to plants as in cultivated systems. Moreover, our recent works show that incidence of plant viruses in nature is considerably high (about 50%) and most of them are new to science. We are still not clear that these plant viruses are non-pathogenic and evolve differently in nature. Some phylogenetic study of the plant viruses in nature show different placement in the phylogenetic tree than their cultivated relatives. It is interesting to know the ecological and evolutionary relationships of these plant viruses and their application on pathological, agricultural and genetic reseach.