Submitted to: Plant Genome Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/15/1999
Publication Date: N/A
Technical Abstract: Rice blast is the most prevalent and damaging disease of rice in the world. We have been developing markers for existing resistance genes for the purpose of marker aided selection, as well as identifying new sources of resistance that can be stacked in durable combinations in new cultivars. IB49 is one of the most predominant races of blast in the southern U.S. There is currently only one major resistance gene (Pi-ta2) deployed in U.S commercial cultivars known to cause an avirulent reaction to this race. The Chinese cultivar 'Teqing' conveys resistance to IB49 and is being used as a parent to develop blast resistance breeding lines. Using low density RFLP and microsatellite markers, the IB49 resistance gene in Teqing has not been found to be associated with any of the resistance loci previously located in U.S. germplasm. We are now using near isogenic lines and representational difference analysis techniques to identify markers linked to IB49 resistance. Representational difference analysis combines the use of subtraction hybridization with the polymerase chain reaction to effectively find RFLP bands present in one genetic line that are not in another. We are using two different sets of near-isogenic (caF13) lines that have been rated as resistant or susceptible to IB49 in inoculated tests. The resistant lines are the sources of tracer DNA and the susceptible lines are used as the driver DNA sources. Genetic analyses of subtraction products are being undertaken to evaluate the success of this approach in identifying disease resistance markers.