TISSUE-SPECIFICITY OF MAIZE SUCROSE SYNTHASE GENE PROMOTERS IN MAIZE TISSUES AFTER PARTICLE BOMBARDMENT

The reporter gene encoding beta-glucuronidase (GUS) driven by either o f the two maize sucrose synthase gene (Sh1 and Sus 1) promoters was in troduced and expressed in various maize tissues via particle bombardme nt. Transient gene expression was examined by histochemical assays. It was found that the two SS promoters directed differential GUS express ion. In the developing kernel, the Sh1 promoter was active only in the upper and central parts of the endosperm. In contrast, strong GUS act ivity controlled by the Sus1 promoter was detected in various types of cells, including the aleurone cells, the subaleurone endosperm cells, the scutellar cells of the embryo and the pericarp cells. Both promot ers showed similar expression patterns in vegetative tissues.