Abstract: In order to apply the EST-SSRs technique in molecular marker aided breeding, gene localization, and gender identification of Fraxinus mandshurica Rupr., a total of 12 100 ESTs from NCBI database were analyzed. The sizes of non redundant ESTs added up to 3.02×10⁶ bp, which can be clustered into 5 423 clads. A total of 9 489 SSRs loci (6-46 bp in length) were found via SSRIT software. Dinucleotide repeats is a predominated feature of these loci (accounting 72.86%), followed by trinucleotide repeats (24.96%) and tetranucleotide repeats (1.37%). The pattern (AG/CT)n is the most frequent one among all repeat patterns, followed by (AC/GT)n and (AT/AT)n. We designed 147 pairs of EST-SSRs primers by Primer 5.0 software. EST-SSRs in F.mandshurica Rupr displayed a relatively high level of occurrence frequency with abundant patterns. These results will pave the way for application of EST-SSRs molecular marker in F.mandshurica breeding.

Key words: Fraxinus mandshurica Rupr., simple sequence repeat, EST-SSR