Abstract: Using SSRIT software，8 188 ESTs of Phalaenopsis from NCBI were screened，according to the standard of repeat motif number above eight. The results showed that 261 SSRs were mined from 246 ESTs with a frequency of 3.19%. Dinucleotide repeats EST-SSRs were dominant，accounting for 94.25% in all SSRs. (TA)_n and (GA)_n were the most frequent motifs，accounting for 26.42% and 25.61% in dinucleotide repeats，followed by (TC)_n，(AT)_n and (AG)_n. Thirty-two primer pairs were designed and 16 primer pairs had expected products using the template of cultivar‘V31’. The sixteen workable primer pairs were chosen to PCR amplification in 16 Phalaenopsis cultivars and 9 primer pairs had polymorphism bands between 2 to 12. The results indicated that it was an effective approach to develop EST-SSR markers based on EST database of Phalaenopsis.

Key words: Phalaenopsis, EST-SSR, molecular marker