Occurrence Of Putative Endornaviruses In Non-Cultivated Plant Species And Characterization Of A Novel Endornavirus In Geranium Carolinianum

Endornaviruses are RNA viruses, which can infect plants yet cause no apparent symptoms. To date, most descriptions of endornaviruses infecting plants have been in cultivated species. A survey for endornaviruses in non-cultivated plants was initiated in 2015 and continued through 2017 in Baton Rouge, Louisiana. Two hundred and seven plant species were tested for distinctive dsRNA profiles by selective extraction and gel electrophoresis, of which seven contained endornavirus-like dsRNA. RT-PCR amplification of an endornavirus-specific sequence supported the endornavirus nature of six of the seven samples. Of the six host species, one species, Geranium carolinianum was confirmed as being infected with a novel endornavirus. The endornavirus in G. carolinianum was characterized and named Geranium carolinianum endornavirus 1 (GcEV-1). The genome of GcEV-1 is approximately 14.7 kb and is related to other endornaviruses, some infecting plants and some infecting fungi. GcEV-1 is a unique plant endornavirus containing genes closely related to fungal and bacterial genes. A GcEV-1 seed transmission test conducted in the greenhouse resulted in a 100% transmission rate. The occurrence of endornavirus-like dsRNA within G. carolinianum was evaluated at three different locations in Louisiana, two within Baton Rouge and one in Belle Chasse. Among the 184 individual plants tested, three individuals were dsRNA-free. There were no clear phenotypic differences in dsRNA-free individuals compared to those containing dsRNA. All three endornavirus-free G. carolinianum plants were collected from the same location. The discovery of only six putative endornaviruses after testing 207 plant species suggests that endornaviruses are not very common in non-cultivated plant species. The results of this study provide a foundation for future research investigating the origin of endornaviruses and the effect endornaviruses have on plants