DEVELOPMENTAL REGULATION OF AN ACYL CARRIER PROTEIN GENE PROMOTER IN VEGETATIVE AND REPRODUCTIVE TISSUES

The expression of an Arabidopsis acyl carrier protein (ACP) gene promo ter has been examined in transgenic tobacco plants by linking it to th e reporter gene beta-glucuronidase (GUS). Fluorometric analysis showed that the ACP gene promoter was most active in developing seeds. Expre ssion was also high in roots, but significantly lower in young leaves and downregulated upon their maturation. Etiolated and light-grown see dlings showed the same level of GUS activity, indicating that this pro moter is not tightly regulated by light. Histochemical studies reveale d that expression was usually highest in apical/meristematic zones of vegetative tissues. Young flowers (ca. 1 cm in length) showed GUS stai ning in nearly all cell types, however, cell-specific patterns emerged in more mature flowers. The ACP gene promoter was active in the stigm a and transmitting tissue of the style, as well as in the tapetum of t he anther, developing pollen, and ovules. The results provide evidence that this ACP gene is regulated in a complex manner and is responsive to the array of signals which accompany cell differentiation, and a d emand for fatty acids and lipids, during organogenesis.