Research On Cucumber Hybrids Purity Detected By EST-SSR Markers

Seed purity is the core indicators of seed quality and the main criteria for classification of seed quality. Low purity seeds used in the production not only failed to increase the production, but brought a huge economic losses to farmers. Cucumber (Cucumis sativus L.) is the annual herbaceous climber.In our country, it has a long cultural history more than 2000 years and play an important role in vegetable production. In the process of cucumber seed production, the false hybrids formed by maternal self and sister across often bring a great loss to cucumber production, and the mixture of different varieties of cucumber hybrid seed is one of the most important factor to reduce the hybrids purity. Therefore, the research on the cucumber seed purity testing methods has great significance.In this research, the experimental materials are Hayan 808 and its parents,Hayan 2186 and its parents and 14 hybrids. Screen SSR, EST-SSR primers and analysis the purity. Take the field morphological identification as standard, then compare the identification results to discuss the accuracy and feasibility of EST-SSR markers in the hybrids seed purity identification. The major results are as follows:1. Compare the different effects of the dosage of template DNA, Mg²⁺, dNTPs and Taq enzyme in PCR amplification, then establish an ideal PCR reaction system to test cucumber hybrids purity.2. According to cucumber's and other melons'SSR primers published in the literature, 41 pairs of SSR primers were synthesized. SSR amplified Hayan 808 and its parents and Hayan 2186 and its parent with the 41 pairs of SSR primers. The results shows that there are no SSR primers can identify parents and F1.3. Designed 102 pairs of EST-SSR primers according to cucumber EST database, then using these primers amplified Hayan 808 and its parents and Hayan 2186 and its parent for SSR .It shows that 2 pairs of primers can distinguish between Hayan 808 and its parents, but can not distinguish between Hayan 2186 and its parents.4. Using 102 pairs of EST-SSR primers to amplify Hayan 808, Hayan 2186 and other 14 hybrids, 2 primers were able to classify the 16 different varieties.The results show that 2 pairs of primers can select Hanyan 2186 and code 5 and divide the others into group at the same time.5. According the filed identification character of Hayan 808 and its parents and Hayan 2186 and its parent to determine the reliability and feasibility of EST-SSR technology. The results show that the SSR molecular identification and field morphological results are consistent. Molecular identification method is reliable, simple and fast. Designing EST-SSR primers can be quickly and accurately identifying the purity of cucumber hybrids.