Abstract: 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) is one of the key enzymes in EMP pathway, involving in the biosynthesis of terpenoids and anthraquinones. Due to the high content of terpenoids and (or) anthraquinones in leguminous plants, it is significant to study the codon bias of dxr gene in leguminous plants in order to understand the regulatory mechanism and further molecular manipulation of dxr gene in leguminous plants. In this paper, codon bias of dxr genes in leguminous was analyzed by CodonW, CHIPS, CUSP and CAI programs, respectively. Moreover, the reliability of the results was verified by dxr genes in Cassia obtusifolia (Leguminosae). The results showed that the codon bias of dxr gene ending with A or U was stronger in leguminous. Compared with Nicotiana tabacum, Arabidopsis thaliana was more suitable as a model plant to carry out functional characterization of dxr gene from leguminous plants. By comparing the codon bias of dxr genes from leguminous plants with that from E. coli and yeast, we found that the difference between yeast and E.coli was significantly lower, suggesting that yeast expression system is more suitable for the exogenous expression system of dxr genes from leguminous plants. However, if the dxr genes of leguminous could be more efficiently expressed in yeast expression system, the codon of dxr genes still needs to be optimized.

Key words: leguminous plants, 1-deoxy-D-xylulose-5-phosphate reductoisomerase, codon bias, phylogenic analysis