Marker Assisted Selection and What It Can Do for You?
Margaret K. Pauls, USDA-ARS
Sarah J. Schultz, University of Illinois
Marker-assisted selection is a vital tool that uses DNA markers to screen plants for phenotypic traits that are favorable to the farmer and ultimately to the consumer. Phenotypic traits are how the plant looks and behaves such as flower color and disease resistance. Flower color and awn type are easy to see with the naked eye, but disease resistance and seed composition require extensive testing. Markerassisted selection utilizes genetics to rapidly screen plants for these traits without labor intensive field or greenhouse studies. Plant breeding programs utilize this technology to make predictions and selections on favorable traits in hours versus days or months, allowing breeders to advance lines with favorable traits while eliminating lines without the favorable traits.
Marker assisted selection can be broken down into four steps: sampling, DNA extraction, genotyping, and selection. During the sampling phase, we take leaf tissue from each plant (even the undesirable ones because we can't tell the difference by looking at them). The most important part of this step is keeping track of what plant goes with each leaf sample. After sampling, all the leaf tissue samples go through DNA extraction. At this step, we want to find the cheapest, quickest, most reliable way to get DNA from the leaves. The next step is genotyping, which includes polymerase chain reaction (PCR) and gel electrophoresis. A specific region of each DNA sample is amplified through PCR. These amplified DNA regions are separated by size with gel electrophoresis. The last step of marker assisted selection is selecting desirable plants based on the genotype and eliminating the undesirable plants from the breeding program. Marker assisted selections allows breeders to advance more lines with the desirable traits at a faster rate.