Impact of eight isolates of Rice Yellow Mottle Virus (RYMV) from Gagnoa (Côte d’Ivoire) on rice (Oryza sp) cultivars production

Abstract

Rice yellow mottle virus, of the genus Sobemovirus, causes a major disease in Africa especially in the lowland and irrigated rice ecologies. Yield losses due to the virus were estimated between 5-100% and depend on genotype. This study, conducted in a screen house, aimed at assessing the impact of eight RYMV isolates from a restrictive environment Gagnoa (Côte d’Ivoire) on 10 differential rice varieties. The plants were inoculated manually by rubbing the leaves from the leaf base to the tip with fingers moistened with inoculum. Virus content and percentage yield reduction of different rice cultivars have been assessed. Result showed that an important variability was observed in the reaction of different rice genotypes infected by different isolates of RYMV. In susceptible cultivars Bouaké 189, PNA647F4-56 and H232-44-1-1 virus content and yield reduction varied respectively from 0.08 to 0.264 and 20 to 95%. In resistant cultivars, Gigante, Lac 23, Morobérékan and Faro 11, virus content and yield reduction varied respectively from 0.03 to 0.188 and 5 to 17%. The lowest virus content and yield reduction was observed with the isolate 7 from upland rice. The significant difference in the interaction observed between the different genotypes of rice and isolates of RYMV suggested the existence of different strains of RYMV within a restrictive environment.
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Keywords: AfricaRice, Sobemovirus, aggressive, virus content, yield reduction, virulence