IN-SITU DETECTION OF EXPRESSION OF THE GUS REPORTER GENE TRANSGENIC PLANTS - 10 YEARS OF BLUE GENES

Among the methods now available to localize the sites of gene expressi on in plant materials, reporter genes based on the gus (uidA) gene of Escherichia coli, which encodes a beta-glucuronidase (E.C. 3.2.1.31; G US), have been the most widely used during the last ten years. The app arent simplicity of the histochemical GUS assay has been a major facto r in the increase in articles using gus genes. However, over the last four years, there have been occasional reports expressing doubts conce rning the specificity of the observed localizations, based on discrepa ncies between results obtained with GUS histochemistry and immunocytoc hemistry and/or in situ hybridization. This brief review compares the results obtained with immunocytochemistry with those obtained with var ious GUS substrates for histochemical studies. Certain sources of arte fact are discussed, as are the limits that should be imposed on interp retation of GUS histochemistry results al the organ, tissue and cell l evels.