In mapping we're trying to develop a sense of where and what 100,000 genes are doing in a plant. When we go in and begin moving things around, having a map of these genes in hand allows us to do a better job of planning the changes we will make. According to Hayes, a critical aspect of mapping is that it allows plant breeders to get an idea of how genes are linked to each other. Most inherited traits are complex, meaning they may be determined by more than one gene and may affect expression of many traits in a plant. Because of this complexity, the plant breeder usually introduces multiple traits in trying to get one desired trait.
Mapping allows plant breeders to see what other characteristics are linked to that one trait.
Hayes has used maps to find genes that offer resistance to stripe rust, a disease that can cut barley yields and is a problem in Oregon. He and colleagues have successfully bred these genes into new varieties of barley. Field testing of these potential new varieties is now underway. In mapping we've made tremendous strides in the past three years. As we reach each new level in this technology we can see new levels ahead that we want to get to.