Development and validation of a new co-dominant DNA marker for selecting the null allele of polyphenol oxidase gene in common wheat ( L.).

Polyphenol oxidase (PPO) is a key enzyme contributing to the time-dependent discoloration of wheat products. Developing cultivars with low PPO activity is one way to solve this problem. In this study, we focused on the gene, which has the second highest effect on grain PPO activity after the gene. Utilizing resequencing data, we found that the gene in the common wheat line 'Fukuhonoka-NIL', which exhibits low PPO activity, has an approximately 3 kb deletion in the 3'UTR and a 73 bp deletion in the third exon. The deletion in the third exon indicated that this allele was the allele, previously identified in the wheat D genome progenitor, Coss. Additionally, the allele in 'Fukuhonoka-NIL' had very low expression, suggesting that this allele is non-functional. We developed a new co-dominant DNA marker for distinguishing the , and alleles and demonstrated that F plants homozygous for the allele exhibited significantly lower grain PPO activity. Additionally, we determined that the allele likely originated from ssp. (lineage 1) accessions. The allele has not previously been found in common wheat ( L., AABBDD genome), and thus the DNA marker developed in this study will be helpful for introducing this allele in common wheat breeding programs.