Mapping Nitrogen Use Efficiency Genes and Searching for QTL Controlling Complex Traits in Barley

Over the past decades, plant scientists have long recognized the need to develop agronomic crops that absorb and utilize nitrogen more efficiently. Two genetic approaches have been tried, the first approach involves one way using traditional breeding, this might be achieved is to use genetics to improve the nitrogen use efficiency (NUE) of a crop plant, and another way using marker assisted selection for key regions of the chromosome that segregate for enhanced NUE and in an attempt to identify genes impacting on NUE. The second approach is of engineering novel genes into constructs to optimize specific aspects of NUE. However, the first approach requires that we should be able to identify QTL of NUE and then use this information to enhance the NUE in agronomic crops. One of the challenges of mapping complex traits is the number of QTL that are often identified, the fact that few of these QTL’s contributing significant variation to be easily detected and the variability from year to year in the location of specific QTL. In this paper, we discussed some of the recent research aimed at improving mapping QTL for NUE, NUE candidates in barley. We use a genomics and bioinformatics approach (synteny-based physical mapping) to map any of the genes in barley varieties with enhanced NUE, applying more classical genetic approaches, based on utilizing existing allelic variation for NUE traits, in addition, presenting the challenge of phenotyping and mapping QTLs for NUE in barley.