Genetic analysis of corn kernel chemical composition in the random mated 10 generation of the cross of Generations 70 of IHO X ILO

To identify and characterize quantitative trait loci (QTL) affecting oil, protein and starch concentration in the corn (Zea mays L.) kernel, plants from Generation 70 of the Illinois High Oil (IHO) and Illinois Low Oil (ILO) populations, previously developed by divergent selection for kernel oil concentration, were crossed. The cross was random mated 10 generations and selfed two generations to develop 500 F1RM10S2 lines. The lines per se and their testcross progenies were evaluated at three locations with two replications for 2 yr. Genotypes were evaluated using 479 SNP markers on a bulk of kernels from each line. Since the parent plants used to make the original cross were not available for genotyping, a multivariable optimization procedure was developed to estimate parental population parameters required for QTL mapping. Simple interval mapping was performed with software specially developed to account for the complex mating structure and the fact that the initial cross was made between populations. Correlations and signs of QTL effects suggest development of high oil-high starch lines would be difficult but that it should be possible to develop high oil-high protein lines. The identification of a large number of QTL (at least 40 each for oil, protein, and starch) with small effects has implications for breeding for improved corn chemical composition.