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Identification of a novel endornavirus in Hydrocotyle spp.

Cesar Escalante Guardado: Louisiana State University Agricultural Center

<div>Endornaviruses are RNA viruses reported to infect plants, fungi, and oomycetes. Plant endornaviruses have a genome that ranges from 13.5-17.6 kb, are transmitted vertically, and do not cause symptoms. Endornaviruses have been found infecting many economically important crops but only in a few non-cultivated plants. <em>Hydrocotyle</em> species include perennial weeds commonly found in wetlands, home lawns, and turf-covered areas in the United States. Using electrophoretic analyses of dsRNA as an initial detection tool, we conducted a survey for endornaviruses in five symptomless <em>Hydrocotyle</em> species collected in south Louisiana. Two species, <em>H. umbellata </em>and<em> H. prolifera</em>, contained endornavirus-like dsRNAs. The dsRNA from both species was purified and sequenced. The sequence of both dsRNAs was similar and contained a single open reading frame, which coded for a polyprotein of 4,773 aa. BLASTp analysis showed that the polyprotein had the highest identity (50 %) with the polyprotein of Lagenaria siceraria endornavirus. Conserved protein domains included helicase, capsular polysaccharide synthase, glycosyl transferase, and RNA-dependent RNA polymerase. Three other <em>Hydrocotyle</em> species, <em>H. bonariensis</em>, <em>H. verticillata</em> and <em>H. ranunculoides</em>, were endornavirus-negative. These results confirm that in south Louisiana, <em>H. umbellata</em> and <em>H. prolifera</em> are infected with a novel endornavirus.</div>