Abstract:

【Objective】 The object of this study was to analyze the SSR distribution in ESTs of pear and develop new EST-derived SSR markers, and application of EST-SSR markers in pear genetic analysis was also validated. 【Method】 All the 1 293 EST sequences of pear were obtained from NCBI. These sequences were screened by using MISA software to search for SSR motifs. Forty-eight pairs of primers were designed by the software Primer3.0 Plus. The PCR products of these primers were detected by PAGE and some of them were recovered for sequencing. 【Result】 The results showed that 92 SSRs were identified from the 82 pear EST sequences. The dinucleotide,trinucleotide and hexanucleotide repeats were the dominant types with the frequency of 48.91%, 17.39% and 17.39%, respectively. Among the 48 EST-SSR primers, 31 amplified distinct bands and expected products, and 27 were polymorphic. There were 83.87% of the PCR products contained the SSR markers. The dendrogram showed that 16 pear cultivars were obviously classified into 2 groups, including the Asian pear and the European pear. 【Conclusion】 Due to the high efficiency of developing SSR markers from pear ESTs, this method will be of great importance in pear genetic analysis.

Key words: pear, EST, SSR, genetic diversity