On the surface, wheat and barley have little to offer the rice genomics research community. They have very large genomes without a physical map, making positional cloning complex, and they are difficult to transform, which hinders the functional analysis of genes and delivery of transgenic technologies. However, shifts in plant genomics research into understanding the basis of diversity and mechanisms involved in creating and maintaining genome complexity have shifted research from a model organism toward more complex species. Wheat and barley are becoming increasingly attractive organisms for many of the new genomics studies. Several key tools have been important for this change, including detailed and well-phenotyped populations, mapping of a large collection of ESTs, and studies of synteny with rice and maize.
Importantly, wheat and barley are widely adapted and there has been extensive monitoring and archiving of genotypes and associated phenotypic data. We also have populations adapted to specific environments and end-uses that have resulted from a long history of selective breeding. These advantages are becoming increasingly significant as analytic tools improve. Early genomics efforts in wheat and barley have delivered useful markers for application in breeding programs and identified key regions of the genome that carry disease-resistance loci, tolerance of abiotic stresses, and components of quality. The expanding resource base for wheat and barley genomics and the new insights being gained into genome organization and behavior of these species offer improvements in our ability to identify new sources of variation and to implement this information in breeding programs.
