Development of markers linked to Diuraphis noxia resistance in wheat usinga novel PCR-RFLP approach

Through random amplified polymorphic DNA (RAPD) analysis we identified a pu tative marker linked to the Dn5 resistance gene. This marker was converted to a more reliable sequence-characterised-amplified regions (SCAR) marker. The initial SCAR marker amplified the correct amplification product but fai led to discern between the susceptible and resistant individuals. Hence, it was utilised to sequence the internal fragment. All nested primers designe d from the internal sequences were also unable to produce any polymorphism between the susceptible and resistant cultivars. Restriction digests were t hen performed on these fragments, and the restriction enzyme EcoRI was able to discern between the susceptible and resistant F-2 individuals of the Dn 5 population. This granted one marker amplified with the internal SCAR prim er set OPF14(1083) the ability to differentiate between parental individual s carrying the Dn5 genes. This marker was tested in a segregating F2 popula tion carrying the Dn5 resistance gene and proved able to differentiate betw een the segregating individuals. This marker may prove useful in marker ass isted selection (MAS), although performing restriction digests may hamper t he throughput of a high number of samples.