Expression pattern of promoters driving eGFP expression in Arabidopsis thaliana hairy roots

Plants are widely used expression system for the production of recombinant proteins. The expression systems mostly rely on promoters. In our study, hairy roots (HRs) of Arabidopsis thaliana were chosen to express the model protein enhanced green fluorescent protein (eGFP). To enhance recombinant protein expression, a strongly expressed promoter in the HRs of A. thaliana from microarray data – MT promoter – was used to control eGFP expression. We obtained different transformation HR lines with equal or lower eGFP production compared with the strong line controlled by the 35S promoter. In rhizocalli, which was induced by growing HRs in the medium supplemented with 2.4-D hormone, much lower eGFP content was quantified. The histological analysis showed that, under the control of MT promoter, eGFP was only expressed in the context, but not in the style or calli-like structure of roots which resulted in lower eGFP production. The structural interaction between the MT promoter and eGFP gene may be responsible for this low eGFP production. Further studies need to be generated to understand the different expression patterns of MT promoters toward heterologous protein eGFP. The discussion was raised when choosing promoters for heterologous protein production to get high productivity.