Two alleles of the single-copy chalcone synthase gene in parsley differ by a transposon-like element

Two types of genomic DNA hybridizing with a chalcone synthase cDNA were isolated from cell suspension cultures of parsley (Petroselinum crispum cv. Mooskrause) and cloned in lambda EMBL4. Their fragmentation patterns with several common restriction enzymes were identical, except for the occurrence of a 927 base pair insertion in one type relative to the other. This insertion is located 538 base pairs upstream of the first of two transcription start sites and has characteristic features of a transposable element. The two types of cloned DNA most likely represent two alleles of a chalcone synthase gene occurring in one copy per haploid parsley genome. The nucleotide sequence and exon-intron structure of the larger allele were determined. Analysis of plants either heterozygous or homozygous with respect to the chalcone synthase gene revealed that both allelic forms were expressed and activated by UV light.