Maize Ionomics Identifies Gene by Environment Interactions Affecting Elemental Accumulation

Heterogeneity in the elemental composition of soils is among the major causes of plant stress worldwide. In order to adapt to these conditions, plants frequently alter their elemental content. We have developed a high-throughput elemental profiling platform to focus on the effect of genetic architechture and soil environment on a plants elemental profile or “ionome”.  We have used this facility to measure the concentration of 20 elements in >30,000 single kernel samples from the Nested Association Mapping panel (NAM) and the Buckler/Goodman Diversity Panel.  Applying this high precision phenotyping technique to the NAM leads to fundamental insights on the genetic regulation of physiology in maize. We identified >200 joint linkage QTLs for the elemental traits from the growout of the NAM in North Carolina 2006. Genome-wide association mapping with the 1.6M HapMapv1 SNPs identified SNPs located within candidate genes underneath the two highest significance joint linkage peaks for Molybdenum.  Association mapping of the diversity panel from 6 growouts revealed that SNPS in one of the candidate genes were significant in all locations, while the SNPs associated with the other gene were only significant in the North Carolina 2006 growout.  Our studies of the maize NAM population will rapidly lead to the discovery of genes important for control of the ionome, assist the development of varieties adapted to stressful soil environments and promote global food security.