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Molecular characterization of wheat polyphenol oxidase (PPO)
1USDA/ARS, Western Wheat Quality Laboratory, E-202 Food Science and Human Nutrition Facility East, P.O. Box 646394, Washington State University, Pullman, WA 99164-6394, USA, tdemeke@grainscanada.gc.ca
Summary
Researchers identified and characterized a wheat polyphenol oxidase (PPO) gene, crucial for understanding browning in wheat products. This study provides the first DNA sequence for a wheat PPO gene, aiding future research into wheat quality.
Area of Science:
- Plant Molecular Biology
- Wheat Genetics
- Enzymology
Background:
- Polyphenol oxidase (PPO) enzyme is linked to undesirable browning in wheat-based foods.
- PPO activity varies across wheat cultivars, but the specific wheat PPO gene remained uncharacterized.
Purpose of the Study:
- To identify and characterize the gene responsible for polyphenol oxidase (PPO) in wheat ( Triticum aestivum L.).
- To obtain the complete DNA sequence of the wheat PPO gene.
- To investigate the relationship between PPO gene presence and enzyme activity.
Main Methods:
- Polymerase Chain Reaction (PCR) amplification using conserved PPO gene primers.
- DNA library screening and Rapid Amplification of cDNA Ends (RACE) to obtain full gene sequence.
- Southern-blot and Northern-blot analyses to assess gene copy number and transcript size.
Main Results:
- A 1,509-bp putative wheat PPO DNA sequence was obtained, showing similarity to other PPO genes.
- Southern blots suggest a limited number of PPO genes in wheat.
- Northern blot analysis revealed a transcript size of approximately 2.0-kb.
Conclusions:
- The study successfully identified and sequenced a wheat PPO gene, providing a molecular basis for PPO activity.
- Distinct hybridization patterns were observed between wheat cultivars with high and low PPO activity.
- Further research is required to fully elucidate the correlation between PPO gene expression and enzyme activity.