QTLs for resistance to Setosphaeria turcica in an early maturing DentxFlint maize population

Quantitative trait loci (QTLs) for resistance to the fungal pathogen Setosp haeria turcica, the cause of northern corn leaf blight (NCLB), were mapped in a population of 220 F-3 families derived from a cross between two modera tely resistant European inbred lines, D32 (dent) and D145 (flint). The popu lation was genotyped with 87 RFLP and 7 SSR markers. Trials were conducted in the field in Switzerland, and in the greenhouse with selected F3 familie s in Germany. The F-3 population segregated widely for resistance with tran sgression of the parents. By composite interval mapping, a total of 13 QTLs were detected with two disease ratings (0 and 3 weeks after flowering). To gether these QTLs explained 48% and 62% of the phenotypic variation. Gene a ction at most QTLs was partially dominant. Eight out of the 13 QTL alleles for resistance were contributed by the more-resistant parent, D145. On chro mosomes 3, 5 and 8, QTLs were located in the same chromosomal regions as QT Ls in tropical and U.S. Corn Belt germplasm. Some QTLs affected NCLB, head smut and common rust at the same time, with alleles at these loci acting is odirectionally.