OBJECTIVETo study the distribution frequency and characteristics of nucleotide repeat of 94 923 ESTs for developing microsatellite primers, providing a theoretical basis and technical support for appropriate conservation and application of sweet wormwood (Artemisia annua).

METHODEST-SSR detection was performed using Perl program MISA. Gene Ontology (GO) annotations were formatted for input into the GOSlim program and the output was parsed to count the occurrence of each GO category. Primer 3 software was used to design 18 pairs primers, amplified products were separated on a 6% denaturing polyacrylamide gel using silver staining.

RESULTBy searching with Active Perl, totally 2 110 SSRs were detected, accounting for 8.6%. The frequency of occurrence of dinucleotide and trinucleotide was 28% and 50.4%, respectively. The most common repeat motifs of trinucleotide were ACC/GGT, accounting for 9.8%. Three hundred and twelve SSR-ESTs were annotated using GO terms. The suitable PCR system of 15 pairs primers was established, and revealed microsatellite polymorphism in 36 individuals.

CONCLUSIONThere are a variety of motifs at EST-SSR locus in sweet wormwood, and more effective amplification and polymorphism in 18 pairs detected primers. Therefore, EST resource is an effective and feasible approach to develop SSR markers, and EST-SSRs will a powerful tool for studies of sweet wormwood genetic resources.