DISTINCT PATTERNS OF PIGMENT SUPPRESSION ARE PRODUCED BY ALLELIC SENSE AND ANTISENSE CHALCONE SYNTHASE TRANSGENES IN PETUNIA FLOWERS

A single-copy sense Chalcone synthase (Chs) transgene driven by a stro ng promoter and producing a fully translatable transcript was converte d to an allelic antisense Chs transgene by Cre-lex-mediated DNA recomb ination in petunia. The sense Chs allele suppressed flower pigmentatio n in a simple pattern determined by cells at the junctions between adj acent petals, as is typical of single-copy sense Chs transgenes of thi s type, whereas the antisense Chs allele produced a different pattern of Chs suppression with white petal edges and reduced pigmentation thr oughout the petal limbs, as is typical of antisense Chs transgenes. In plants carrying a lex-flanked Chs transgene, the presence of Cre prot ein can cause both sense-specific and antisense-specific patterns to b e superimposed in the same flower, suggesting that sense and antisense suppression by single-copy transgenes are mediated by different mecha nisms or occur in different cellular or developmental compartments. Th e presence of Cre also causes the production of numerous, non-clonal w hite spots, suggesting that the turnover state is not cell-autonomous.