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Identification of Molecular Markers Linked to Head Smut Resistance Gene (Shs) in Sorghum by RFLP and RAPD Analyses. B. J. Oh, Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843, Present address: Department of Horticultural Sciences, Texas A&M University, College Station 77843; R. A. Frederiksen, and C. W. Magill. Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843. Phytopathology 84:830-833. Accepted for publication 13 May 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-830.

Restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) methods were used to find markers linked to a head smut resistance gene (Shs) in sorghum. To select parents for a mapping population, RFLPs were identified between four resistant accessions (Lahoma Sudan, White Kafir, SC325, and CS3541) and four susceptible accessions (RT×7078, SC170-6-17, BT×399, and BT×623) for three restriction enzymes (EcoRI, EcoRV, and HindIII) with 43 maize genomic clones. Since SC325 (resistant) and RT×7078 (susceptible) showed the maximum RFLP frequency, these accessions were selected for mapping. Fifty-two F2 progenies from a selfed cross between accessions SC325 and RT×7078 were used to map the Shs locus. One hundred twenty-four sorghum genomic clones with five restriction enzymes (BamHI, EcoRI, EcoRV, HindIII, and XbaI) and 326 RAPD markers were used for linkage analysis with Shs. Linkage of RFLP and RAPD loci with Shs was verified by using F3 lines to determine the Shs genotypes of the F2 plants after inoculation with a race 5 isolate of Sporisorium reilianum. RFLP and RAPD analyses revealed that RFLP loci detected by probes pSbTXS560 and pSbTXS1294 and one RAPD locus from primer OPG5 were linked to Shs.

Additional keywords: bulked segregant analyses, sorghum hybrid breeding.