Marker-assisted selection in sugar beet: a breeder's perspective.

Today a large number of DNA markers is available in sugar beet as a tool for breeding applications. In the case of monogenic traits and majorgenes, development of markers and their use in breeding programs is well advanced. The predictive value of a marker is mostly determined by marker inheritance and the linkage between marker and trait. The stability of the marker-trait association within breeding material determines the diagnostic value of a marker. Data from a test of markers for Rhizomania resistance demonstrate these characteristics. For quantitative traits these parameters are much more difficult to estimate. Therefore the use of markers for quantitative traits in marker-assisted selection was limited in the past. Future research including functional genomics may be able to explain single factors for quantitative traits rather than whole complex traits.