Virome and Experimental Analysis Reveal Tryptophan-Like Dissolved Organic Matter Contributes to the Persistence of Plant Viruses in River Water.

Plant viruses are devastating plant pathogens, resulting in annual losses exceeding billions of dollars in global agriculture. Once outside their plant host and insect vectors, plant viruses encounter unfavorable environmental factors that can accelerate their decay. However, plant viruses have been observed to persist in aquatic environment. The reasons why many plant viruses remain stable and infective in aquatic environment for extended periods are still largely unknown. In this study, a virome approach is utilized to examine the presence of plant viruses in river water. The results indicated that tryptophan-like dissolved organic matter (Try-like DOM) may play a crucial role influencing the abundance of plant viruses in river water. Further experiments found that Try-like DOM can protect plant viruses under simulated natural conditions. This protective phenomenon is attributed to Try-like DOM adopting a "swimming firewall mode", i.e., free Try-like DOM can act as a firewall to effectively absorb ultraviolet (UV) light, helping plant viruses avoid the harmful effects of UV radiation and free radicals. These findings offer new insights into the mechanisms underlying the persistence of plant viruses in aquatic environment, which would be helpful in developing strategies to control the spread of plant viruses.