IDENTIFICATION OF MOLECULAR MARKERS LINKED TO HEAD SMUT RESISTANCE GENE (SHS) IN SORGHUM BY RFLP AND RAPD ANALYSES

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 (RTx7078, SC170-6-17, BTx399, and BTx623) for three restriction enzymes (EcoRI, EcoRV, and HindIII) with 43 maize genomic clones. Since SC325 (resistant) and RTx7078 (susceptible) showed the maximum RFLP frequency, these accessions were selected for mapping. Fifty-two F-2 progenies from a selfed cross between accessions SC325 and RTx7078 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 F-3 lines to determine the Shs genotypes of the F-2 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.