marker-assisted selection in wheat - ictsd

60Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fishSummaryThis chapter provides an example of using marker-assisted selection (MAS) for breedingperennial ryegrass (Lolium perenne), a pasture species. A mapping study had shownthe presence of quantitative trait loci (QTL) for seven component traits of nitrogen useefficiency (NUE). The NUE-related QTL clustered in five chromosomal regions. TheseQTL were validated through divergent marker selection in an F 2 population. The criterionused for plant selection was a summation index based on the number of positive QTLalleles. The evaluation studies showed a strong indirect response of marker selectionon NUE. Marker selection using a summation index such as applied here proved to bevery effective for difficult and complex quantitative traits such as NUE. The strategy iseasily applicable in outbreeding crops to raise the frequency of several desirable allelessimultaneously.