Screening rice (Oryza sativa L.) varieties for resistance to rice yellow mottle virus

Abstract

Rice yellow mottle virus (RYMV) is the most important virus disease of rice in Africa. It is spread all over Cote d’Ivoire and is responsible of large production losses. Until now, control measures of the disease are based on the exploitation of natural resistance sources. Thirty nine (39) rice varieties (14 irrigated and 25 rain fed) from NCAR (National Center of Agronomic Research) collection were screened for the resistance to RYMV. Using the couple symptoms/grains weight, as evaluation criteria, it appeared that different varieties groups presented different levels of sensitivity to RYMV. Thus, in lowland ecosystem, Moroberekan variety, of japonica type, appeared to be highly resistant whereas WITA9 and WAT316 varieties, of indica type, were resistant. On the other hand, IDSA46, IDSA62, IDSA74 and IDSA76 varieties of japonica type were tolerant in upland ecosystem. Symptoms severities were related to grains weight reduction which is varietal related. The existence of resistant/tolerant varieties to RYMV as found in this study suggests that the NCAR germplasm collection is a potential reservoir of resistance genes. It is therefore necessary to keep on exploring it in order to use them in breeding program.