Inheritance of Resistance to Rice Yellow Mottle Virus in Interspecific and Intraspecific Rice in Uganda

Rice Yellow Mottle Virus sobemovirus (RYMV) has been noticed as major constraint of both upland and lowland rice. It is highly infectious, variable and several resistance-breaking strains have been identified. The effective control was mainly directed to breeding for resistance. The study aims to understand the mechanism of resistance and number of genes conferring resistance to rice yellow mottle virus (RYMV) in interspecific and intraspecific rice. The Research is being conducted at National Crop Resources Research Institute. Nine genetic materials, 5 susceptible and 4 resistant have been used in full diallel crossing design to generate F1’s. Preliminary data showed that the interspecific lines were cross-compatible with genetic materials resistant to RYMV. This indicates that the interspecific lines can simply be used to generate new rice genotypes by introgression or extraction of valuable genes in them. The inheritance of resistance will be determined after a diallel evaluation by inoculating F2’s + Parents and scoring for reaction to the virus. Furthermore, this study aims to estimate heritability of resistance to RYMV within advanced generations (F3, F4 & F5). Preliminary data showed that regression of F4 bulk on F3 progeny rows was significant for number of tillers (P<0.05), but was not significant for plant height (P>0.05). Heritability for various traits indicates that selection should be successful for most traits.