Crown gall oncogenesis: evidence that a T-DNA gene from the Agrobacterium Ti plasmid pTiA6 encodes an enzyme that catalyzes synthesis of indoleacetic acid.
Stable incorporation of tumor-inducing (Ti) plasmid sequences, the T-DNA, into the genomes of dicotyledonous plants results in the formation of crown gall tumors. Previous genetic studies have suggested that the products of the genes encoding transcripts 1 and 2, which are encoded by the TL-DNA region of pTiA6, are responsible for inducing the auxin-independent phenotype of crown gall tissues. Here we report the construction of a plasmid, pMTlacT2, which directs the synthesis of the Mr 49,800 polypeptide encoded by the transcript 2 gene. Cell-free extracts prepared from Escherichia coli harboring this plasmid converted indoleacetamide to indoleacetic acid, the natural auxin of plants; extracts prepared from plasmidless strains of E. coli or strains harboring the cloning vehicle pBR322 did not carry out this reaction. We conclude that the transcript 2 gene of pTiA6 codes for an enzyme that participates in auxin biosynthesis, probably an indoleacetamide hydrolase.
D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D005798:Genes, Bacterial; D007210:Indoleacetic Acids / Q000096:biosynthesis*; D010941:Plant Tumors; D010957:Plasmids; D012231:Rhizobium / Q000235:genetics*; D014158:Transcription, Genetic
D007210:Indoleacetic Acids; C030737:indoleacetic acid; D004262:DNA Restriction Enzymes