Codon Usage Bias of the Wheat Flower Development Gene WAG-2 and Other AGAMOUS Group Genes

Analyzing codon usage bias of WAG-2 gene in wheat three-pistil (TP) mutant may provide a basis for selecting the appropriate host expression systems to improve the expression of target genes. In the present study, we analyzed the codon bias of the complete coding sequence (CDS) of the WAG-2 gene in TP using Codon W program, and compared the results with AGAMOUS (AG) group genes of other plant species. Results showed that the WAG-2 gene in TP and other monocot AG group genes preferably used codons ending with G/C bases, but Arabidopsis thaliana, Nicotiana tabacum, and other dicot crops were biased toward the synonymous codons with A/T. The clustering results based on codon bias were consistent with those based on CDS of the AG group genes, indicating that the difference in codon preference of AG group genes sequences was closely associated with the genetic relationship of the species. The Euclidean distance coefficients of WAG-2 with A. thaliana and N. tabacum were 9.255 and 5.730, respectively, indicating that N. tabacum may be more suitable for the expression of WAG-2. There were 37 codons showing distinct usage differences between WAG-2 and genome of yeast, 23 between WAG-2 and Escherichia coli. Therefore, the E. coli was the superior protein expression system. These results may improve our understanding of codon usage bias and functional studies of WAG-2.