Regulation of the lactose operon in vitro. I. Transcription of the lactose operon

Biological and molecular evidence for the transgenosis of genes from bacteria to plant cells

Specialized transducing phages (lambda and varphi80) have been used as vectors in the transfer of genes (wild type and mutant) from the bacterium Escherichia coli to haploid cell lines of the plants Lycopersicon esculentum and Arabidopsis thaliana. The overall phenomenon of transfer, gene maintenance, transcription, translation, and function has been termed transgenosis. Transgenosis of galactose and lactose operon genes was detected by survival and growth of the plant cells on defined medium with galactose and lactose as sole sources of bulk carbon. Phages carrying a defective operon, unrelated bacterial genes, or no bacterial genes, do not affect the normal result of death on these media, nor do they prevent growth on optimal growth media. Transgenosis of the E. coli gene z (lac operon) was confirmed by a biochemical-immunological test specific for E. coli beta-galactosidase. Plant cells were unable to effectively suppress an E. coli nonsense mutation. The E. coli mutant suppressor gene, supF(+), specifies insertion of tyrosine at amber (UAG) nonsense codons. Introduction of supF(+) results in a lethal transgenosis on medium normally optimal for plant cell growth. It is concluded that amber codons are vital to the life of plant cells. Differentiating cells of A. thaliana were not affected by supF(+).