Figure 4. Multiplex PCR using primer sets capable of selecting for both the Glu-D1d and the null Wx-B1 alleles. The 425 bp product is amplified from the wild type Wx-B1a allele but is not produced from the null Wx-B1b allele (Nakamura et al. 2002). The plant in lane 8 carries the Glu-D1d and null Wx-B1 alleles.