Expression patterns of two genes for the delta-subunit of mitochondrial F-1-ATP synthase from sweet potato in transgenic tobacco-plants and cells

Two nuclear genes, F(1)delta-1 and F(1)delta-2, coding for the delta-subuni t of mitochondrial F-1-ATP synthase, which corresponds to oligomycin-sensit ivity conferring protein in animal and yeast mitochondria, were isolated fr om sweet potato. The gene for the delta-subunit was composed of 6 exons and these two genes shared high sequence similarities to each other not only i n exons but also in introns and in the 5'-upstream regions, However, the 5' -upstream regions of F(1)delta-1 and F(1)delta-2 were distinguishable by th e presence of novel sequences, designated Ins-1 and Ins-2, respectively. In s-1 and Ins-2 contained a terminal direct repeat of 10 bp and 12 bp, respec tively, and various forms of repeal sequences. The promoter fusion of both F(1)delta-1 and F(1)delta-2 nith the GUS coding sequence gave expression of GUS activity in transformed tobacco BY-2 cells, although the levels of GUS activity and the patterns of expression during the growth of cells were di fferent between the two. In transgenic tobacco plants, the two fusion genes showed similar levels of expression in leaves and stems, while F(1)delta-2 :GUS gave significantly higher levels of expression in roots than F(1)delta -1:GUS. Deletion of Ins-1 from the 5'-upstream region of F(1)delta-1:GUS di d not affect: the expression of the fusion gene in various organs of transg enic plants. However, it caused significant enhancement of expression in tr ansformed tobacco BY-2 cells.