Using auxin-response element (DR5), we constructed reporter expression plasmids containing the recombinant reporter gene DR5::GUS for study of the auxin distribution in vivo. Two constructions were designed using pBI121, one of which is pBI121–DR5(Ω′)::GUS, where the 5′UTR of GUS was replaced by the 5′UTR of TMV (Ω′) and the other is pBI121–DR5::GUS with 5′UTR of GUS unchanged. We transferred the two recombinants into tobacco leaf by infiltration and the transient expression was tested two days later. The GUS reaction was strong with infiltrated pBI121–DR5::GUS but there was no GUS activity with the pBI121–DR5(Ω′)::GUS. RNA was isolated from the infiltrated leaf discs and subjected to RT–PCR with specific primers of GUS. The GUS mRNAs were detectable in the infiltrated cells transferred with either pBI121–DR5::GUS or pBI121–DR5(Ω′)::GUS, and the corresponding β–glucosidase expression was achieved in the former plasmid but not the latter plasmid. It recommended the 5′UTR sequence of Ω′ do not improve the gene expression of GUS, but do inhibit the translation of the mRNA in our study. .