Association Mapping for Seed Traits in Arabidopsis and Maize

Association Mapping for Seed Traits in Arabidopsis and Maize
Phenotypic variation of the majority of agronomically important crop traits is under polygenic control and understanding the genetic and molecular basis of natural variation within and between populations will be essential for connecting genes and alleles to phenotypes. Carotenoids and tocochromanols (tocopherols and tocotrienols) in plant-based foods are dietary sources of provitamin A and vitamin E and are required at minimum daily levels for optimal health in human and animal diets. To enhance our knowledge of the polygenic nature of these compounds in agricultural seeds, we are leading a consortium of researchers transferring and leveraging information for carotenoid

(provitamin A), tocochromanol (vitamin E), selected B vitamins and essential amino acid biosynthesis from the model system Arabidopsis to the economically important crop maize. Using data from Arabidopsis, we have identified and annotated orthologs for these various biosynthetic pathways in the maize genome. Whole genome and candidate gene association studies in both maize and Arabidopsis are being used to identify novel genes, functional variant alleles, and the genetic architecture of seed carotenoid, tocochromanol, B vitamin and essential amino acid traits. Genetic mapping data from the two organisms will be integrated with expression data obtained from developing seeds using next generation whole transcriptome sequencing to delineate potential candidate genes responsible for carotenoid and tocochromanol traits. Through our integrated genetic, genomic, molecular, and computational approaches, we will be able to fine map and assess the molecular basis of epistatic interactions among known pathway genes and novel loci affecting these traits. Not only will this enable a comparative analysis of the genetic architecture of these traits between Arabidopsis, a dicot, selfing species with maize, a monocot, outcrossing species, but it will also be directly useful for improving essential micronutrient content in maize through on-going breeding programs.