The promoter of TL-DNA gene 5 controls the tissue-specific expression of chimaeric genes carried by a novel type of Agrobacterium binary vector

Summary A plant gene vector cassette to be used in combination with various Escherichia coli gene-cloning vectors was constructed. This cassette contains a replication and mobilization unit which allows it to be maintained and to be transferred back and forth between E. coli and Agrobacterium tumefaciens hosts provided these hosts contain plasmid RK2 replication and mobilization helper functions. The cassette also harbors a transferable DNA unit with plant selectable marker genes and cloning sites which can be combined with different bacterial replicons, thus facilitating the reisolation of transferred DNA from transformed plants in E. coli. The vector cassette contains two different promoters derived from the T-DNA-encoded genes 5 and nopaline synthase (NOS). By comparing the levels of expression of the marker enzymes linked to each of these promoter sequences, it was found that the gene 5 promoter is active in a tissue-specific fashion whereas this is not the case for the NOS promoter. This observation provides the first documented instance of a gene derived from a procaryotic host the expression of which is apparently regulated by plant growth factors.Abbreviations OCS octopine synthase (gene) - NOS nopaline synthase (gene) - NPT-II neomycin phosphotransferase (gene) of transposon Tn5 - vir Ti-plasmid region encoding virulence functions - Cb carbenicillin - Gm gentamycin - Km kanamycin - Cm chloramphenicol - Sm streptomycin - Sp spectinomycin - Rif rifampicin - Ery erythromycin - bom basis of mobilization - ori_r origin of conjugational plasmid transfer - Tra, Mob functions required for conjugational transfer of plasmids - BAP N⁶-benzylaminopurine - NAA -naphthaleneacetic acid - CTAB N-cetyl-N,N,N-trimethyl-ammonium bromide