The tomato Dwarf gene isolated by heterologous transposon tagging encodes the first member of a new cytochrome P450 family

To transposon tag the tomato Dwarf (D) gene, a tomato line that carries a T-DNA containing the maize Activator (Ac) transposable element closely linked to D was pollinated with a stock homozygous for the d mutation. Hybrid seedlings were screened for dwarf progeny, and three independent dwarf lines were obtained. Two of these lines showed inheritance of a recessive phenotype similar to that conferred by the extreme dwarf (d(X)) allele. Variegation for the dwarf phenotype in one of these lines suggested that D had been tagged by Ac. Genomic DNA adjacent to Ac in these two lines was isolated by use of the inverse polymerase chain reaction, and the two insertions mapped similar to 2 kb apart, Partial complementation of d was observed when the corresponding wild-type sequence was used in transformation experiments. A cDNA clone of D was sequenced, and the predicted amino acid sequence has homology to cytochrome P450 enzymes.