First report of Rice stripe necrosis virus infecting rice in Benin.
In December 2012 and March 2013, rice plants with unusual leaf symptoms were observed on Africa Rice research fields at Cotonou, Benin. Some plant accessions died because of severe attacks. Surveys conducted in March 2014 (300 to 400 plants/accession assessed) indicated that 51 out of 57 lowland and 55 out of 62 upland accessions were diseased with an incidence of 0 to 37% in upland (respectively on e.g., accessions NERICA L-20 and IR68702-07-2-1-4-B) and 0 to 26.6% in lowland (respectively on e.g., NERICA L-34 and NIL 130-1-3). The symptoms consisted of crinkling yellow foliar stripes and severe plant malformation. These symptoms suggested the presence of Rice stripe necrosis virus (RSNV), a nonenveloped rod-shaped multipartite virus from the genus Benyvirus in the family Benyviridae that is transmitted by Polymyxa graminis, a plasmodiophorid protist. First described in 1977 in Côte d'Ivoire, the disease was reported in Nigeria, Liberia and Sierra Leone, in several countries of America, and more recently in Burkina Faso. Based on the results of PCR, nucleotide sequencing and virus transmission assays, the causal agent was confirmed as RSVN. This is thought to be the first report of RSNV infecting rice in Benin.