Working Document Series Open Access 2010 RUF-34477

Inheritance of resistance to rice yellow mottle virus disease in selected rice cultivars in Uganda

G. AseaR. EdemaJ. LamoM.L. Mogga

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Abstract

222 words

Rice yellow mottle sobemovirus (RYMV) has been identified as the most destructive viral disease in lowland and upland rice. In this study, the mode of inheritance of resistance to a prevalent RYMV strain in Uganda was determined for five resistant lines (upland NERICAs 8, 11, 12, 13 and Gigante (an O. sativa lowland variety). These resistant lines were crossed with four susceptible lines (lowland NERICAs 4, 6, 10 and IR64 (an O. sativa lowland variety)) in a full diallel mating design. Segregating F2 progeny were planted in both field and screenhouse in an α- lattice design, and inoculated by standard mechanical procedures. GCA effects were significant (P<0.001), and were larger than SCA effects. Both the field and screenhouse experiments strongly expressed genotype differences. GCA, SCA and reciprocal effects were significant (P<0.001) in both experiments. The narrow sense coefficient of genetic determination based on genotype means was relatively high in both screenhouse (76%) and field (84%) experiments. These results suggest that additive gene effects were more important than non-additive effects, and that selecting as early as F2 or F3 generations can be effective. However, reciprocal effects showing a consistent tendency of F2 progeny to reflect the resistance level of the female parent indicates the need for careful choice of male and female parents in hybridization programs to achieve RYMV resistance in the offspring.

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5 categories
Agricultural research Pests of plants Plant diseases Plant genetics and breeding Research methods

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