PROMOTERS OF NUCLEAR-ENCODED RESPIRATORY-CHAIN COMPLEX-I GENES FROM ARABIDOPSIS-THALIANA CONTAIN A REGION ESSENTIAL FOR ANTHER POLLEN-SPECIFIC EXPRESSION/

Regulatory promoter regions responsible for the enhanced expression in anthers and pollen are defined in detail for three nuclear encoded mi tochondrial Complex I (nCI) genes from Arabidopsis thaliana. Specific regulatory elements were found conserved in the 5' upstream regions be tween three different genes encoding the 22 kDa (PSST), 55 kDa NADH bi nding (55 kDa) and 28 kDa (TYKY) subunits, respectively. Northern blot analysis and transgenic Arabidopsis plants carrying progressive delet ions of the promoters fused to the beta-glucuronidase (GUS) reporter g ene by histochemical and fluorimetric methods showed that all three pr omoters drive enhanced expression of GUS specifically in anther tissue s and in pollen grains. In at least two of these promoters the -200/-1 00 regions actively convey the pollen/anther-specific expression in ga in of function experiments using CaMV 35S as a minimal promoter. These nCI promoters thus contain a specific regulatory region responding to the physiological demands on mitochondrial function during pollen mat uration. Pollen-specific motifs located in these regions appear to con sist of as little as seven nucleotides in the respective promoter cont ext.