Identification of Maize Grain Fe and Zn Homeostasis-Associated QTL in Two Mapping Populations.

Iron (Fe) and zinc (Zn) are essential for plant, animal and human nutrition. Low Fe and Zn in crops and livestock results in their reduced health, which over time can negatively impact the nutritional status of human populations. Maize is grown worldwide, as a staple crop for some and a valuable commodity for others, and has the potential to be a useful tool for addressing dietary Fe and Zn deficiency among the undernourished poor. Maize’s remarkable global spread is largely due to the degree of genetic and phenotypic diversity that can be harnessed into adaptation to local conditions. This study was performed on the Goodman Diversity Panel with corresponding analysis of the nested association mapping (NAM) population, to take advantage of greater statistical power and resolution and to perform joint linkage (JL) and genome-wide association (GWAS) analyses of quantitative trait loci (QTL) across 3 temperate and 2 tropical locations. Previous studies that have used a candidate-gene knockout approach have yielded narrower successes in identifying genetic determinants of ionomic homeostasis, whereas the NAM JL-GWAS approach, in this study, has identified many significant QTL. Currently 227 JL ionomic-QTL have been identified.  With successive rounds and accompanying GWAS data we anticipate discovery of good QTL for Fe and Zn homeostasis. A web interface for browsing the maize co-expression network has been developed for querying individual genes or large regions of the genome.