Genomic Approaches Provide Novel Tools for Rapid Cloning of Major QTL in Large Cereal Genomes

The molecular identification of genes underlying important agronomic traits is a major goal in crop research. In the cereal genomes the cloning of such genes is hampered by the large genome size which is a problem for map-based cloning. In addition, genomic information and available sequence data are often from a genotype that does not have the specific trait of interest, e.g. a resistance gene or QTL. Finally, many interesting genes are located in recombination-free regions of the genome. Thus, it is of great interest for the cereal research community to have easier and more rapid tools available for gene isolation and two approaches will be presented here. First, we have developed a new approach, MutChromSeq, which relies on flow-sorting and sequencing of chromosomes from mutants in the particular trait of interest. This approach is feasible for major QTL for which specific mutants can be identified. It can easily be implemented if appropriate NILs for quantitative loci are available or can be developed. Second, the combination of exome capture data from 500 wheat lines (EU project WHEALBI) and the IWGSC 2014 draft sequence of the wheat genome allowed us to use GWAS to “land” near genes of interest. These novel tools will greatly simplify the molecular identification of genes in large cereal genomes.