Genetic basis of Fusarium ear rot resistance and productivity traits in a heterozygous multi-parent recombinant inbred intercross (RIX) maize population.

Maize (Zea mays L.) is one of the most productive crops worldwide. As a heterotic crop predominantly grown as F₁ hybrid, maize exhibits challenges for genetic studies of complex traits, since homozygous genotypes, which are largely used in these studies, may not accurately reflect what happens in cultivated conditions. To map Fusarium Ear Rot (FER) resistance to Fusarium verticillioides and traits with potential impact on yield, including phenology, we constructed a recombinant intercross (RIX) population. This was achived by crossing pairs of recombinant inbred lines (RILs) derived from a multi-parent maize population. We characterized the RIX population over two growing seasons, employing artificial F. verticillioides inoculation. The heterozygous background of the material enabled the identification of QTL and candidate genes through in silico reconstruction of RIX genotype probabilities. A total of 37 loci were identified using single-year BLUPs while 29 with joint-year BLUPs. These, included several known QTL associated with days to tasseling, kernel row number and a QTL on the chromosome 9 associated with FER resistance. In this region, we could identify candidates based on their predicted functions and potential roles in plant-pathogen interactions and/or resistance mechanisms. These QTL represent potential breeding targets to FER resistance and yield components in commercial maize varieties.