Genes used in plant molecular biology sometimes have low expression in plants due to the fact that they have been originally isolated from bacteria which use a different codon usage.
The betaglucuronidase (GUS) gene from E. coli was codon optimized for better expression in monocots and dicots. To prevent expression from bacteria the StLS1 intron was introduced. The synthetic GUS gene is regulated by the Ubi promoter from maize and introduced into maize embryos by particle gun bombardment. For comparison the GUS gene from Jefferson et al. (EMBO J. 87 Dec) was used, which is 100% identical in amino acid sequence and in the sourrounding of the genes.
| GUS gene
(Jefferson et al. 87)
|Optimized Gus gene
by adapted codon usage