Development and Characterization of EST-SSR Markers from NCBI and cDNA Library in Cultivated Peanut ( Arachis hypogaea L. )

86 132 ESTs downloaded from GenBank in NCBI and 12 501 ESTs from cDNA library constructed by high-oil linoleic acid accession E12 were analysed. After the preprocession, there were 18 051 singletons and 9 972 contigs in the GenBank of NCBI and cDNA library. Totally 3 104 SSR locis had been screened by MISA software, accounting for 11.08% for these non-redundant ESTs. All SSR locis are divided into di-nucleotide, thi-nucleotide, tetra-nucleotide, penta-nucleotide, hexa-nucleotide and multi-nucleotide etc., and thi-nucleotide motif is the most motifs and the frequency was 43.0% and 56.8% in NCBI and cDNA libraray, respectively. The number of di- and penta-nucleotide motifs were second and third in all motifs. And the hexa-nucleotide was the least motif both in NCBI and cDNA library. In all repeat motifs nucleotide, AG/TC was the most motifs and accounted for 8.65% and 13.42% in NCBI and cDNA library respectively. Among the tri-nucleotide repeats, CTT/GAA was the most frequent motif, accounting for 6.7% and 13.42%, respectively. The repeat unit number of SSR locis is between 4 and 51.