Back to top Gene Maps Help Breeders A genome is an organism's complete set of chromosomes. And, if you'll recall from your high school biology course, chromosomes contain the genetic material that determines the characteristics of all living things. Chromosomes occur in pairs within cells and all organisms have a particular number of pairs of chromosomes. Humans, for example, have 23 pairs of chromosomes. Barley plants have seven pairs.
Chromosomes are linear in form, and for that reason, so are gene maps.
Gene maps allow plant breeders to establish the relative location of genes of interest-in this case genes for barley stripe rust resistance. Scientists do this by identifying other genes adjacent to the gene of interest. The second Back to top step is important because genes are usually passed from parent to progeny in groups. Therefore, when we cross parent plants to get a gene for resistance in the progeny, we know genes for other characteristics will come along with a resistance gene. It's generally possible to identify at least one of the genes associated with the gene of interest using laboratory processes called electrophoresis and DNA sequencing.