Genetic mapping in maize with hybrid progeny across testers and generations: Grain yield and grain moisture

Most complex quantitative traits in maize (Zea mays L.), especially grain yield, display low correlations between the trait values observed in inbred and hybrid progeny. Comparisons of quantitative trait loci (QTL) controlling inbred per se and hybrid performance are needed to understand the underlying genetic factors, and to determine the utility of QTL detected in the two progeny types. DIVA markers were used to identify QTL for grain yield and grain moisture in hybrid progeny of F-2.3 and F-6.8 lines from a Mo17xH99 population. For both generations, testcross progeny were developed by crossing the lines to three inbred testers (B91, A632, B7S). Each testcross population was evaluated in field trials with two replications in eight environments, The testcross progeny from the two generations were evaluated at the same locations but in different years. QTL were identified within each testcross population and for mean testcross (MTC) performance, Individual tester QTL effects were not consistent in rank or detection across generations; however, parental contributions were consistent. MTC effects were more consistent across generations with most of the QTL with large effects being detected across generations. QTL detected with only one tester were not necessarily detected for the other two testers, especially for grain yield, but parental contributions were consistent when QTL were detected in a region for more than one tester. The QTL for grain yield identified in tills population for inbred and hybrid progeny show only partial correspondence, indicating that marker-assisted selection programs would need to identify and incorporate QTL For both progeny types.