Different transcript abundance of two divergent ATP synthase subunit 9 genes in the mitochondrial genome of Petunia hybrida.

The mitochondrial genome of Petunia hybrida line 3704 has been found to contain two transcribed genes for the proteolipid subunit of the ATP synthase complex (atp 9). The 5' and 3' flanking sequences of the second atp 9 gene differ from those of another atp 9 gene previously sequenced by Young et al. (1986), while the coding region exhibits only one silent base change. The transcript termini of the two divergent atp 9 genes map to different locations, most of which are surrounded by sequences homologous to putative mitochondrial transcription signals (Hiesel and Brennicke 1985; Schuster et al. 1986; Young et al. (1986). Because transcripts from the atp 9 genes differ in abundance, divergence in the flanking regions of these two genes must affect regulatory elements which control either transcription rate or transcript stability.