Identification of Quantitative Trait Loci Associated with Anthracnose Resistance in Sorghum [Sorghum Bicolor (L.) Moench].

Sorghum grain and forage production in warm and humid environments is severely affected by anthracnose disease, caused by the fungal pathogen Colletotrichum sublineolum Henn. Of the many control strategies for anthracnose, employment of host plant resistance has been regarded to be the most effective. Various sorghum genotypes have been known to possess multiple sources of genetic resistance to different races of the pathogen. To elucidate the genetic basis of anthracnose resistance, two mapping populations, each consisting of 100 recombinant inbred lines (RIL) were derived by crossing BTx623, an anthracnose susceptible line with two different anthracnose resistant lines, SC155-14E and SC414-12E. RILs and parents were evaluated in replicated field trials in four environments. Linkage maps for the two populations were constructed using Digital Genotyping, a genotyping-by-sequencing method developed specifically for C4 grasses.  A major quantitative trait locus (QTL) for the BTx623 × SC155-14E RIL population, was identified on chromosome 10 in three of the four environments examined, which explained 20% of the phenotypic variation. In the BTx623 × SC414-12E RIL population, a major QTL explaining 40% of the phenotypic variation was identified on chromosome 5 in three of the four environments. The information provided by these QTLs will be of significance in marker-assisted pyramiding of multiple sources of anthracnose resistance into elite sorghum germplasm.