Study On Polyphenol Oxidase In Wheat Varieties

In this study, 199 wheat varieties were measured to determine their variation in PPO activity and the polyphenol content. The method of polyphenol activity was also discussed. Then 19 varieties among them was selected for PPO isozyme electrephoresis and PCR analysis. The results were as follows:1. The influence of polyphenol in wheat kernels to the PPO activity can be reduced by using PVPP. When the content of PVPP was 1%, the highest activity of PPO could be measured.2. By the analysis of PPO activity to the 199 wheat varieties, the distribution of PPO activity was concentrated on 32-466U/g/min. Among these varieties, Annong9267, Annong9043, Wenxian4,MW18, Yangmail58 , the PPO activity is high. But in Annong9192, Xiaobingmai, Jinmai47, the PPO activity is low.3. The Nature-PAGE were similitude in different varieties at the same growth stage. The PPO isozymes changed with the development of kernels. Up to 9 PPO isozymes could be detected in the immature kernels, but at the end of mature, the number of isozyme slabs reduced to 5.4. Only one slab was found in all the 19 varieties which be studied by PCR. This result showed that these wheat varieties have the common sequence in PPO gene. The difference of PPO activity would be the result of different metabolism regulation.5. There were significant difference in polyphenol content of 199 wheat varieties. No correlations were detected between polyphenol content and PPO activity. This suggested that the occurrence of discoloration of flour, pasta and some food was mainly caused by the variations in PPO activity.