The characterization of anther-specific promoter encoding chalcone synthase isolated from Lilium Oriental hybrid cv. Acapulco

Anthocyanins are the major pigments contributing to flower coloration. A 1584 bp 5' upstream sequence of ALCHS2 gene was isolated from Acapulco lily (Lilium Oriental hybrid cv. Acapulco). Computer-based analyses (GeneScan, AtPAN) predicted a CAATBOX1 and putative transcription factor-binding sites, including tissue-specific elements. When gALCHS7 promoter–gus fusion was introduced to petunia ('Dream Red'), all ten putative transgenic plants showed localized GUS activity in the anther, but five of them also showed weak GUS activity in the ovule. No distinctive signal in the leaf and petal was detected in the same stage. To clearly determine the operation of the promotor region, anther and ovule tissues of transgenic line 6 were fixed in paraffin for dark-field analysis. At 1 cm length of floral bud, a GUS signal was not observed in the anther, but weak expression was observed in the ovule. Before anthesis, GUS protein was highly expressed in the pollen, endothecium, and epidermis. Fluorometric GUS assays of individual organs taken from four transgenic plants demonstrated that all lines showed high GUS activity in the anther compared to 35S CaMV promoter (pBI1 121), except line 34. Using the truncated promoters by cis-acting elements, we found that minimal region (gALCHS7-7, 270 bp) displayed GUS expression only in the anther, though at weaker activity than in the original promoter.