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 carrie s a T-DNA containing the maize Activator (Ac) transposable element clo sely linked to D was pollinated with a stock homozygous for the d muta tion. Hybrid seedlings were screened for dwarf progeny, and three inde pendent dwarf lines were obtained. Two of these lines showed inheritan ce of a recessive phenotype similar to that conferred by the extreme d warf (d(X)) allele. Variegation for the dwarf phenotype in one of thes e lines suggested that D had been tagged by Ac. Genomic DNA adjacent t o 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, P artial complementation of d was observed when the corresponding wild-t ype 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.