Tissue-specific expression of genes encoding isoforms of the mitochondrialATPase beta subunit in Nicotiana sylvestris

We report here that the catalytic beta subunit of the mitochondrial ATPase/ ATP synthase is encoded by a small multigenic family in the diploid tobacco Nicotiana sylvestris (nsatp2 genes). cDNAs and, genes corresponding to the beta l, beta 2 and beta 3 (pollen specific) isoforms previously detected b y 2D-SDS PAGE were isolated. Nsatp2.1 and nsatp2.2 transcripts were found i n all vegetative and reproductive tissues analysed. In contrast, nsatp2.3 t ranscripts were found exclusively in bicellular pollen. As a whole, steady- state transcript levels of nuclear nsatp2 and mitochondrial atp1 genes were found to be closely correlated.