Potential risk of plant viruses entering disease cycle in surface water in protected vegetable growing areas of Eastern China.

With the expansion of protected vegetable growing areas (PVGAs), viral plant diseases have become more prevalent, causing severe economic losses to the vegetable production industry in China. At present, researches on plant viruses mainly focus on plants, but there is only a few reports on the species of viruses in surface water from PVGAs. The surface water samples in PVGAs are representative to a certain extent, which has an important reference value for studying the characteristics of plant viruses in surface water. The purpose of this study was to identify the diversity and the possibility of entering disease infection cycle of plant viruses in water samples collected from PVGAs in eastern China. A total of 144 water samples were collected, and eight plant viruses including tobacco mosaic virus (TMV, 8.33%), cucumber green mottle mosaic virus (CGMMV, 33.33%), pepper mild mottle virus (PMMoV, 6.94%), cucumber mosaic virus (CMV, 0.69%), tomato masaic virus (ToMV, 3.47%), tomato mottle mosaic virus (ToMMV, 0.69%), tomato chlorosis virus (ToCV, 4.17%), and tomato yellow leaf curl virus (TYLCV, 5.56%) were examined using RT-PCR and PCR. The species of viruses in surface water varied greatly by location. CGMMV, TMV, ToCV, ToMV, ToMMV, and TYLCV were identified in Shandong, a northern part of Eastern China, whereas only PMMoV was found in Shanghai, a southern part of Eastern China. After healthy tobacco plants were inoculated with the concentrated solutions of TMV, ToMV, CGMMV, and PMMoV, could cause disease in healthy tobacco, indicating that the plant viruses in the concentrated solution have the infectivity, and the plant viruses in surface water have the possibility of entering the infection cycle of disease. The results will improve the understanding of the potential risks of waterborne disease transmission.