Assessment of Eight Rice Genotypes to Rice Yellow Mottle Virus under Semi-controlled Conditions in Côte d’Ivoire

Abstract

Rice is the second most produced cereal crop worldwide. In Côte d’Ivoire, rice constitutes the staple food of the population. Despite its importance, rice production is constrained by numerous factors, including rice yellow mottle disease, a viral infection affecting rice. This study aimed to identify new sources of resistance to Rice Yellow Mottle Virus (RYMV) through the screening of high-yielding rice varieties selected under lowland conditions. Eight rice genotypes and one RYMV isolate were used. The experiment was conducted in a greenhouse following a randomised complete block design with three replications. Rice seeds from each genotype were sown in plastic pots filled with sterilised soil. Plants were mechanically inoculated 14 days after sowing (DAS). Serological tests using anti-RYMV antibodies were performed on leaf samples collected from inoculated plants. Symptom severity scores were recorded at 14 and 60 days after inoculation (DAI). The impact of RYMV on plant height, number of tillers, number of panicles, and thousand-grain weight was also assessed. The first RYMV symptoms were observed at 5 DAI in the varieties Bouaké 189 and Soungrouba, whereas the hybrid AR034H and the variety Wita 9 expressed symptoms at 6 and 7 DAI, respectively. Serological analysis revealed high viral concentrations in Bouaké 189, Soungrouba, and AR034H. The hybrids AR051H (8.66 DAI), AR043H (10.00 DAI), AR593H (11.66 DAI), and the variety Giganté (13.33 DAI) expressed symptoms later. The impact of RYMV was most pronounced in Bouaké 189, with average reductions of 77.77%, 56.16%, 45.55%, and 71.51% in panicle number, tiller number, plant height, and thousand-grain weight, respectively.