Analysis of codon bias of SS gene in Astragalus membranaceus

In order to provide theory basis for selecting appropriate expression systems，synonymou codon bias of squalene synthase（SS）gene of Astragalus membranaceus（AmSS）was analyzed with EMBOSS and Codon W programs，and AmSS with other seven plants and E.coli genome was compared. The results showed that AmSS was bias toward the codons with A and T at the third codon position，and there were 22 significantly different codons between AMSS and SS of E.coli genome. Therefore，codons of AmSS are needed to be optimized to improve its expression level in E.coli.