It is well-established that polyphenol oxidases (PPOs) are involved in undesirable brown discoloration of wheat based products like chapattis, noodles and flat bread. Results from our laboratory suggest the presence of at least six PPO genes in hexaploid wheat, falling into two clusters with three similar sequences each. One gene from each cluster was used as a probe for Southern blot analysis and gene expression studies. Southern blot analysis performed on four different wheat varieties (Rampart, Utah-100, Reeder, Vic) with three restriction enzymes revealed 2-4 DNA fragments. Gene expression studies showed that one group (GenBank #AY596268, AY596269, AY596270) of genes was expressed both in kernels and flag leaves, 2-4 week post anthesis (WPA) and the other group (GenBank # AF507945, AY596266, AY596267) of genes was not detected either in kernels or in leaves. The gene (GenBank#AY596268) was expressed as a MBP fusion protein in E. coli, purified and used for antibody production. Protein expression studies were performed on flag leaf and kernel samples of four different wheat varieties (as mentioned above). These studies indicated that our antibody exhibited immunological reactivity with protein bands of 67 and 85 kD, probably processed and precursor PPO in kernels. The 67 kD band was detected 4-5 WPA with maximal levels at 6 WPA. In the durum variety Vic, a 75 kD band was detected instead of a 67 kD band as observed in the other varieties. The antibody exhibited reactivity with a single protein band of 76 kD in leaves with maximal levels 3-4 WPA. Enzyme kinetic assays showed PPO activity 4-6 WPA and 3-4 WPA in kernels and leaves, respectively. Our results suggest that three genes contribute to kernel PPO activity, and that activity levels are controlled both at the level of transcription and post-transcriptionally.