Codon usage bias analysis for the spermidine synthase gene from Camellia sinensis (L.) O. Kuntze

The spermidine synthase (SPDS) gene exists widely in all types of plants. In this paper, the codon usage of the SPDS gene from Camellia sinensis (CsSPDS) was analyzed. The results showed that the codon usage of the CsSPDS gene is biased towards the T-ended or A-ended codons, which is similar to that observed in 73 genes selected from the C. sinensis genome. An ENC-plot for 15 SPDS genes from various plant species suggested that mutational bias was the major factor in shaping codon usage in these genes. Codon usage frequency analysis indicated that there was little difference between the CsSPDS gene and dicot genomes, such as Arabidopsis thaliana and Nicotiana tabacum, but significant differences in codon usage were observed between the CsSPDS gene and monocot genomes, such as Triticum aestivum and Zea mays. Therefore, A. thaliana and N. tabacum expression systems may be more suitable for the expression of the CsSPDS gene.