| Germplasm resource of cold-resistant pear have great value to fruit tree. The further study in DNA level will be scientifical and effective for the conservation and utilization in the future. RAPD marker was used as the main method of research in this experiment. By researching genetic diversity of germplasm resource of cold-resistant, indicating relative and classifying status of different germplasm and searching special RAPD markers of different germplasm, it can make an offer of proof for cultivar identification and hybrid early identification and construct elementarily core collection of resources of cold-resistant of fruit tree. It will be convenient to manage resources and utilize genetic diversity effectively. The main researches were as followed:1. The method of'SDS"was used for the extraction of DNA from the leaves of the pear. The components of the SDS extraction liquid were improved and increased the quality and quantity of DNA2. The suitable reaction system and amplification procedure were found. The reaction mixture contained 20ng/μl template DNA in a 25μl reaction volume, with 10pM RAPD primer 1.0μl, 1.0U Taq DNA polymerase, 0.2mmol/L dNTP, and 2.5μl PCR Buffer. Amplification was performed in a UNOⅡthermal cycle programmed for 35 cycles(94℃for 45s; 37℃for 45s; 72℃for 120s) followed by an extension at 72℃for 5min, and then keep at 4℃.3.RAPD technic was used to study the cold-resistant pear 107 germ plasm rasouse of the heredity variation process, 13 primer was screened out from the 180 primer that was used to expand, 105 DNA stripwere expanded which of 99 special DNA strip,which achieved the percent 94.3%,the average primer was expanded the 8of DNA strip.4. There was more than one cultivar specific markers in 6 cold-resistance pear,and cultivar identification and hybrid early identification might be done using cultivar specific markers.5. 84 primary core collection was constructed to make use of the expanded DNA,and put up again clustering analyse.Conclusions as follows:①p.ussriensis Max,p.bretscheideri Rehd and p.communis L of the sutra system was validate that is the same of the former.but the some wildness breed is different from the sutra system,which is worthing to lucubrate.②Cluster dendrogram and the resemble modulus of ping guoli and the other varietal indicate that:ping guoli gathered with the p.bretscheideri Rehd,but the surface of the character is p.bretscheideri Rehd and p.pyrifolia Nak mixed system,ping guoli and bretscheideri Rehd of the relative is near that show ping guoli classify of the status vest in bretscheideri Rehd.6.Core collection constructed that was attempt to the cold resistant pear germplasm resources,28 core collection was achieved, core collection of the diversity and practicability were proved.The constructed fingerprinting provided useful information not only for developing superior cultivars and new variety right protection but also for conserved and utilized the cold-resistant pear germplasm resources. The improved systems could be used for constructed genetic map, marker-assisted selection and map based cloning in cold-resistant pear. The results, therefore, will produce important effects on genetic improvement at the molecular levels.
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