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item SUN, D
item XIA, X
item HE, Z
item ZHANG, L
item Morris, Craig
item APPELS, R
item MA, W
item WANG, H

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2005
Publication Date: 5/31/2005
Citation: Sun, D.-., Xia, X.-., He, Z.-., Zhang, L.-., Morris, C.F., Appels, R., Ma, W.J., Wang, H. 2005. A novel sts marker for polyphenol oxidase activity in bread wheat. Molecular Breeding 16:209-218.

Interpretive Summary: The activity of the enzyme polyohenol oxidase (PPO) in wheat grain is associated with the discoloration of Asian noodles and other wheat foods. Using DNA sequences for PPO from public databases, PCR primers were designated that produced two different-sized PCR products. The size of each was shown to be related to PPO activity among a special set of wheat genetic lines, termed "doubled-haploid" lines. Further, the PCR product size difference was shown to be located on wheat chromosome 2AL. This PCR "marker" will be an effective tool for selecting low PPO wheat breeding lines, thereby producing varieties with lower PPO discoloration.

Technical Abstract: The enzyme activity of polyphenol oxidase (PPO) in grain has been related to undersirable brown discoloration of bread wheat (Triticum aestivum L.) based end-products, particularly for Asian noodles. Breeding wheat cultivars with low PPO activity is the best approach to restrain reduce the undesirable darkening. Use of m Molecular markers w could greatly improve selection efficiency in breeding programs. Based on the sequences of PPO genes (GenBank accession numbers AY596268, AY596269 and AY596270) conditioning PPO activity during kernel development, 28 pairs of STS[CM1] primers were designed using the software ‘DNAMAN'. One of the markers from AY596268, designated as PPO18, can amplify a 685-bp and a 876-bp fragment in the cultivars with high and low PPO activity, respectively. The STS marker PPO18 was mapped to chromosome 2AL using a DH population derived from a cross Zhongyou 9507 × CA9632, and a [CM2]set of nulli-tetrasomic lines and ditelosomic line 2AS of Chinese Spring. QTL analysis indicated that the PPO gene was co-segregated with the STS marker PPO18 that which is closely linked to Xgwm312 and Xgwm294 on chromosome 2AL, explaining 28~43% of phenotypic variance for PPO activity across 3 three environments. A total of 233 Chinese wheat cultivars and advanced lines were used to validate the correlation between the polymorphic fragments of PPO18 and grain PPO activity. The results showed that PPO18 is a co-dominant, [CM3]cost-saving, and reliable molecular marker for PPO activity and can be used in wheat breeding programs targeted for noodle quality improvement.