Mapping Complex Traits in Plants: Nitrogen Use Efficiency in Barley As a Case Study

Plant scientists have long recognized the need to develop crops that absorb and utilize nitrogen more efficiently. Two genetic approaches have been tried, the first approach involves using traditional breeding and marker assisted selection in an attempt to identify genes involved in NUE. The second approach involves using novel gene constructs designed to improve specific aspects of NUE. One of the challenges of mapping complex traits is the number of QTL that are often identified, the fact that few of these QTL contribute significant variation to be easily detectable and the variability from year to year in the location of specific QTL. Discussed will be some recent research aimed at improving mapping NUE QTL, NUE candidate genes and the statistical challenges faced, in this type of research.