Postharvest Pear Polyphenol Oxidase (ppo) Isozymes And Genetic Relationship With The Browning Of Fruit

Pear good for our traditional cultivars, main problem is that core browning after postharvest. There are a lot of research had done in abroad, most scholars believed that the fruit browning caused by PPO is one of the main factors. The current research emphases on the relationship of pear PPO activity and phenols content. Not in depth study in its mechanism, so that browning of pear can not make a effective progress. Therefore, from the molecular point of view of the relationship between PPO and pear browning browning of the pear is sentences have revealed important.The experiment is based on the use of Polyacrylamide gel electrophoresis to study the pears PPO i sozyme changing regular rattern. What is more, Semi-quantitative RT-PCR amplification to study the relationship of the PPO gene variation and fruit senescence, browning. The pear which were used rapid and slow cooling methods for early, middle and late harvest maturity of pear pulp, pith and seeds.he results were summarized as follows:Firstly, the PPO activity in slow cooling is slower than the same maturity pear with the rapid cooling, which is the same with the change of browning index of fruit core.It was indicating that PPO is closely related with the pear browning. Also indicateed slow cooling can inhibit browning of pear. Meanwhile, in the early adoption of pear, the PPO activity is the toppest, late harvest is second, and minimum harvest is the least. It is also Noted that the different maturity is one of factors that affect the browning of pear.Secondly, Through studying in PPO isozyme changes trend and PPO activity, founded that in the flesh, the impact of PPO activity of isozymes A, B; in fruit hearts, the impact of PPO activity of the range of isozymes A and B; in the seed, the impact of mining pear PPO activity of the range of isozymes C, D, affecting early and late Pear PPO activity of isoenzymes for the C, D, F.Thirdly, GenBank through the genes in pear designed and setted the primers P (5'-CAT AT GACGT CTCTT TCACC TCCGG TAGTC-3'5'-CGGGA TCCTT AAGAA GCAAA CTCAA TCTTG ATAC-3') to obtain RT-PCR product (1780bp),have a 99% homology with the pear, and it is only expressed in the fruit heart. Another, Q (5'-GCT TCA AGC AAC AGG CAG CCGT G-3'5'-CGT TGA CAC ATT GTC CTC GGT CC-3) to obtain RT-PCR product (315bp), have a 97% homology with the pear, it can express in the fruit heart and fruit pulp. Actin genes have been identified, primer is (5'-CAG TGG TCG TAC AAC TGG TAT-3'5'-AGG TAG CTC ATA GCT CTT CTC-3').The last,it is founed that gene P is the key gene affect PPO activity and gene Q is have a close relation with PPO activity.