| There are abundant pear resources in Dangshan County, Anhui province. The yield of Dangshan su pear holds the great share in the world pear market. Many new types of pear (Pyrus.) have been forming in the long history of pear evolution because of the complex genetic background and a lot variation from mutation and cross between species. So it will be very significant to study and reasonably utilize the germplasm resources for accelerating the program of pear breeding.The RAPD analysis was undertaken with 24 biotypes, which were cultivated in Dangshan. The main results were as follows:1. Two kinds of method—CTAB and SDS—were applied to extract the genomic DNAs of young leave, mature leave, phloem and dormant bud. The results showed that the CTAB method was better than SDS method based on the compare of DNA purity, color, yield, amplification etc. The DNAs extracted from young leave by two methods all had good quality and yield. The DNA from mature leave extracted only by improved CTAB method could be suitable for RAPD analysis. The yield of DNAs was very low, which were extracted from phloem and dormant bud by either SDS or CTAB method.2. The parameters in RAPD reaction system were determined by orthogonal experiment: In the system of 25μl, the quantity of template DNA is 60ng; primer 4pmol; dNTPs 5×10-9mol, 10×PCR Buffer 2.0μl; MgCl2 5×10-8mol; Taq polymerase 1.0U.3. The DNA fingerprint constructed by the special bands of 6 arbitrary primers could identify 9 biotypes of 14 ones. The Fingerprint constructed by the patterns of 8 arbitrary primers could completely discriminate whole biotypes studied.4. The genomic DNAs of 22 biotypes were amplified by RAPD analysis using the 40 steady arbitrary primers screened from 60 ones. The result of cluster analysis showed that all studied biotypes could be divided into five groups in the threshold of similarity coefficient from 68.6 to 70.4. The first group was mainly Pyrus bretschneideri, including Dangshan su pear and its mutants, Yali, Xuehuali, Laiyangcili. The second group was all P. pyrifolia except for Huangguanli, including: Niitaka, Kosui, Nichisaki, and Cangxili. The third group was composed of Kuerle pear and Hongxiangsu. Fusu and Pyrus betulaefolia formed a group respectively.5. The result of stepwise discriminant analysis showed that the Fisher functions were only relative with 4 loci—S54 1500bp,S58 1375bp,S58 947bp and S1461 831bp. The Fisher equations were as follows: Y 1= -27X1+18X2-18X3+18X4-19.609；Y2 = 9X1-3.60×10-15X2+3.597×10-15X3-3.60×10-15X4-5.209；Y3 = 31.5X1-13.5X2+22.5X3-13.5X4-19.609；Y4 = 31.5X1-4.5X2+40.5X3-22.5X4-35.3596. Comparing with contrasted cultivar, eight mutants of Dangshan su pear were analyzed by RAPD analysis with 60 arbitrary primers. The result showed that Baguaisu had no changing band, Lianglizaosu had 29 changing bands, Xiusu 10, Xipisu 6, Biansu 4, Hanghuaxu 3, Lengsu 2, and Wangsu 1.
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