Genetic control of resistance to rice yellow mottle virus disease in two rice crosses

Rice yellow mottle virus (RYMV) disease is the leading biotic stress affecting rice (Oryza sativa L.) production in Africa, causing yield losses ranging from 10% to 100%. In Ghana, most of the leading aromatic rice varieties are susceptible to RYMV disease. In this study, two resistant genotypes (Gigante and K150710) were crossed to a leading aromatic variety (CRI-AgraRice), which is susceptible to RYMV, to determine the mode of inheritance of RYMV disease using both Mendelian and quantitative methods. While the Mendelian segregation pattern suggested a single recessive gene is responsible for resistance to RYMVD in Gigante, the quantitative methods indicated that up to two genes could be responsible for RYMVD resistance in the CRI-AgraRice x Gigante cross. Resistance to RYMVD in the AgraRice x Gigante cross was explained by duplicate epistasis. The inheritance of resistance to RYMVD in CRI-AgraRice x K150710 was polygenic, with up to five genes being responsible and with the gene action fitting into an additive-dominance model. Heritability and genetic advance for the two crosses were high, indicating that breeding for resistance to rice yellow mottle virus disease is feasible.