Characterization of the S-RNase promoters from sweet cherry (Prunus avium L.)

Genomic DNA fragments containing the S₃-, S₄, and S₆-RNase genes were isolated from the sweet cherry (Prunus avium L.) and sequenced. Comparison of the 5′-flanking sequences of these three S-RNases indicated that a highly conserved region (designated CR) existed just upstream from the putative TATA boxes. We postulate that CR contains cis-regulatory element(s) involved in pistil expression. To examine the activity of the isolated S-RNase promoters of sweet cherry in the pistil, we transiently introduced approximately 650-bp fragments of the S₄- and S₆-RNase promoters fused to β-glucuronidase (GUS) gene into the pistil of the petunia using a particle bombardment technique. Histochemical analysis showed that the 5′-flanking region of each S-RNase was active in the pistil. This suggests that cis-regulatory element(s) for pistil-specific expression may exist(s) within the 650-bp region upstream from the TATA box in the sweet cherry S-RNase promoter.