Characterization of microsatellites of ovule transcriptome in Pinus tabulaeformis

In order to understand the molecular mechanism of regulating ovule development of Pinus tabulae-formis thoroughly and clarify the influence of microsatellites in ovule development, we used the program MISA to mine and analyze the high-throughput sequencing in earlier experiments to seek the microsatellites of transcriptome, in an attempt to provide significant information and data for deeper research. A total of 1412 SSRs were identified in 1274 unigenes with one SSR per 2.15kb. Among 87 SSR repeat motifs of ovule transcriptome, (A/T)n was in the maximum proportion, accounting for 45.89%. Mononucleotide and trinucleotide repeats were the two more abundant in all repeat types, accounting for 46.88% and 34.99%, respectively. The microsatellites with length below 20 bp were in the majority and those over 20 bp amounted only 5.67%. It showed a negative relation between the frequency of occurrences and the length of microsatellites. Most of SSRs were in untranslated region, and only 232 SSRs were located in protein-coding regions, while 18 in both of them. Trinucleotide repeats were the richest in protein-coding regions (105, 45.26%).