Figure 1

Diagram of the PCR primers used to distinguish the Rht-B1b and Rht-D1b genes [30]. The primers on the right differentiated the wild-type (WR1 and WR2) from the mutant (MR1 and MR2) genes by a single nucleotide change in the coding region. The primers cannot, however, distinguish between the genes on homeologous chromosomes 4B and 4D. The primers on the left-hand side differentiated between the 4B and 4D genomes because the upstream promoter regions have undergone sufficient evolutionary change to be distinguishable from each other. The figure is based on Ellis et al. [30] emphasizing the challenges faced when studying multiple gene copies in the wheat genome.