Genomewide Recurrent Selection for Fusarium Ear Rot and Fumonisin Resistance in Maize

Fusarium ear rot (FER) is a disease of maize caused by Fusarium verticillioides, which produces fumonisin (FUM), a mycotoxin linked to human and animal health risks. Sources of resistance to FER have been identified, but the resistance is polygenic and difficult to incorporate into elite hybrids. Extensive field trials, laborious inoculation, and expensive antibody assays are required to reliably assess resistances to FER and FUM contamination in breeding populations. Genomic selection (GS) could improve the efficiency of breeding for these complex disease resistance traits by training selection models on a subset of a breeding population and applying them to a larger sample of genotyped but untested lines from the population. This can increase the number of lines screened beyond the limits of field screening capacity, effectively increasing selection intensity. To evaluate the potential utility of GS in an ongoing maize breeding program, we called 6131 SNPs on 508 S_0:1 families from an advanced generation of a recurrent selection program using low coverage sequence. A training set of 263 S_0:1 lines was evaluated for FER and FUM at three locations during two years. The remaining 245 S_0:1 lines were evaluated as an independent validation set in a subsequent year. Preliminary results have shown that we can obtain high correlations between predicted and true genetic values for FER (>0.5) and FUM (>0.6). This provides evidence that GS is a very promising breeding strategy for Fusarium resistance and can be applied in a recurrent selection breeding program to increase the genetic gain.