Predicted QTL Locations for Fusarium Ear Rot (FER) Resistance in Maize and the Generation of Improved FER Resistant Maize Inbred Lines.

Quantitative trait loci (QTL) found through screening of maize mapping and breeding populations are useful in the selection of quantitative traits such as pathogen resistance.  In this study two breeding populations of maize, generated from parents of similar genetic background, were analyzed to predict QTLs associated with fusarium ear rot resistance (FER).  The populations were also used to generate FER resistant inbred lines for commercial production and crop improvement.  FER is caused by Fusarium verticillioides, which produces harmful mycotoxins in the seed.  These mycotoxins can be harmful and even deadly to animals and humans.  The FER resistance donor parent NV14FR was crossed with the susceptible parents NV14 and NV35 to create the NV14/NV14FR population and the NV35/NV14FR population.  QTL locations were predicted by analyzing the polymorphic markers on the F₂ plants for each population and matching the genotypes to the mean scores of the subsequent F_2:3 ears.  The predicted QTL locations were also matched to previous QTL locations reported in similar studies to support the presence of a QTL in a specific genomic region.  One QTL on chromosome 5 (bin 5.05) was predicted from the NV14/NV14FR population which is located in the same region as a previously found QTL.  Two QTL were predicted from the NV35/NV14FR population located respectively on chromosome 6 (bin 6.07) and chromosome 7 (bin 7.04).  The QTL on chromosome 6 was also found in a genomic region previously identified as important for FER resistance.  Three resistant RILs, from the NV14/NV14FR population, were tested in a hybrid combination at 25 locations throughout MN, IL, IA, IN, MI, and WI.  The three RILs had improved FER resistance with equal or greater hybrid performance than the isoline check.  Marker assisted selection in breeding populations using the QTLs identified in this research will facilitate in the selection for FER resistance.