The present invention provides a novel reporter gene assay. In particular, the present invention provides a histochemical reporter gene assay employing α-
L
-arabinofuranosidase in combination with a chromogenic α-
L
-arabinofuranosidase substrate. The α-
L
-arabinofuranosidase histochemical reporter assay may be utilized to characterize gene regulatory regions of interest either alone or in combination with other assays.