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Figure 3. (A) Schematic representation of F3'5'H genomic sequences. Top graphic represents the components of the F3'5'H genomic sequence isolated from the L79-908 (W1) line. The three solid blocks are three exons predicting a cDNA 1801 bp in length. The two blocks representing introns of 754 and 2102 bp in length are shown in hatched lines. Bottom scheme is a graphic summary of the F3'5'H genomic sequence isolated from the ‘Williams’ isoline with the w1 allele. The three solid blocks represent the three exons predicting a slightly larger cDNA of 1854 bp. Exon 3 is 53 bp longer in the F3'5'H gene of the w1 white-flowered line than in the F3'5'H gene of the W1 purple-flowered line. The small block above exon 3 represents the extra 53 bp that contains part of the tandem repeats (arrows) resulting from the 65-base insertion (53 additional bases and 12 bases of sequence substitution). The two introns (755 bp and 2104 bp respectively) in the F3'5'H alleles isolated from both the w1 and W1 isolines are very similar in size and sequence. (B) Small tandem repeats in the F3'5'H gene of plants with the w1 white flower allele. Nucleotide numbering is from the Williams (w1) genomic sequence. The nucleotide sequence and translated amino acids flanking the insertion are shown. Nucleotides in lowercase italic letters denote the 53 extra bases of the insertion. Highlighting denotes two identical 37-bp repeats found at positions 4242 to 4278 and 4289 to 4325 that are separated by 10 nucleotides. Bold letters indicate the 12 nucleotides of the uninterrupted F3'5'H allele that are replaced by the 65-bp insertion. Also marked is the 21 nucleotide repeat found at position 4189 to 4209 in both the F3'5H alleles of the W1 line and w1 isolines that matches a portion of the tandem repeat unit of the insertion. The conserved P450 heme-binding domain is underlined. * denotes the premature stop codon created by the insertion.
