Development Of STS Marker For Grain PPO Gene In Common Wheat

High PPO activity in grain or flour of wheat is responsible for the undesirabletime-dependent darkening of bread wheat based products. It is necessary for breedingprograms to develop cultivars with very low PPO activity targeting for products. Based ona wheat grain DNA sequence AB254804(GenBank Accession Number) mapped tochromosome2B, some pairs of primers were designed. A group of wheat cultivars withhigh and low PPO activity were amplified to find PPO gene alleles. A total of195cultivars were used to verify the association between PPO activities and the STS marker.1.we developed a gene-specific marker (F-4) for low PPO activity. Three fragmentswere detected in the cultivars with low PPO activity155.95A475U（/min·g·10~3）and a singlePCR fragment (about400bp) in the cultivars with high PPO activity246.22A475U/（min·g·10~3）. The marker F-4was mapping to chromosome2A using a set ofnulli-tetrasomic lines of Chinese Spring. Thus, the STS markersF-4is a efficient andreliable markers for the evaluation of PPO activity and can be used in wheat breedingprograms.2.In the present study, we developed a gene-specific marker (F-8) for low PPOactivity. This marker detected double PCR fragments (400and600bp) in the cultivarswith low PPO activity and a single PCR fragment (400bp) in the cultivars with high PPOactivity. Through sequence analysis and blast search in NCBI, we found that Sequence of bis very similar to GQ303713which was positioned on the2B chromosome. Screening ofthis marker on195Chinese wheat micro-core collections showed that the double fragmentswere present in150genotypes and the single fragments in the remaining45genotypes.Through statistical analysis of data, the cultivars with the double fragments (a and b）hadsignificantly lower mean PPO activity than those with single fragments(Sequence of a).Thus, the STS markers F-8is a efficient and reliable markers can be used in wheat breeding programs.3.The genotypes carrying Ppo-2Ab, Ppo-2Da and Ppo-2Ba showed the lowest PPOactivity[118.76A475U/（min·g·10~3）], carrying Ppo-2Ab, Ppo-2Da and Ppo-2B showedthe higher PPO activity than the former[153.48A475U/（min·g·10~3）],while the genotypescarrying PPO-2Aa, PPO-2Db and PPO-2Bb showed the highest PPO activity[358.42A475U（/min·g·10~3）]. the genotypes carrying Ppo-2Aa, Ppo-2Db and Ppo-2B showed thePPO activity232.92.Thus, the STS markersF-8along with F-4and STS01is the efficientand reliable marker combination for the evaluation of PPO activity and can be used inwheat breeding programs to improve the quality of noodles and other end products.