Evidence for non-proteinaceous inhibitor(s) of β-glucuronidase in wheat (Triticum aestivum L.) leaf and root tissues

Abstract

The GUS gene of E. coli, encoding β-glucuronidase, has been widely used as a reporter gene in plant transformation. However, β-glucuronidase activity in transgenic wheat leaf or root tissue is rarely observed or reported. To address this question, we investigated three wheat lines transformed with the GUS reporter gene. We found all three lines expressed GUS mRNA as well as β-glucuronidase protein in their leaf and root tissues as detected by RNA gel blot, ELISA, and immunoblot analyses. However, β-glucuronidase enzyme activity was only detected in pollen grains from the transgenic plants. Fluorometric and histochemical assays performed in the presence of wheat tissue extracts indicated that wheat leaf and root tissues contain inhibitor(s) of β-glucuronidase activity, but pollen grains contain much lower concentrations. Further characterizations indicated that the inhibitor(s) is of low molecular weight (<10 kDa) and is non-proteinaceous. © Springer 2005.