Showing papers by "Pal Maliga published in 1991"
TL;DR: The mutation in the SPC23 line is the first reported case of a mutation close to the region of the 16S rRNA involved in the formation of the initiation complex, which provides markers for selecting plastid transformants.
Abstract: Nicotiana tabacum lines carrying maternally inherited resistance to spectinomycin were obtained by selection for green callus in cultures bleached by spectinomycin. Two levels of resistance was found. SPC1 and SPC2 seedlings are resistant to high levels (500 μg/ml), SPC23 seedlings are resistant to low levels (50 μg/ml) of spectinomycin. Lines SPC2 and SPC23 are derivatives of the SR1 streptomycin-resistant plastome mutant. Spectinomycin resistance is due to mutations in the plastid 16S ribosomal RNA: SPC1, an A to C change at position 1138; SPC2, a C to U change at position 1139; SPC23, a G to A change at position 1333. Mutations similar to those in the SPC1 and SPC2 lines have been previously described, and disrupt a conserved 16S ribosomal RNA stem structure. The mutation in the SPC23 line is the first reported case of a mutation close to the region of the 16S rRNA involved in the formation of the initiation complex. The new mutants provide markers for selecting plastid transformants.
91 citations
TL;DR: It is reported that the narrow substrate range AAC(3)-I enzyme from the transposable element Tn21 [2] also provides a useful gentamycin resistance marker in plants.
Abstract: Acetylation of the amino group in position 3 of the 2-desoxystreptamine moiety [AAC(3)] of gentamycin is a potent and wide-spread resistance mechanism in bacteria. Several marker genes coding for AAC(3) enzymes with varying substrate ranges or differing molecular properties have been identified. The enzymes AAC(3)-I and AAC(3)-II have a narrow substrate range and confer resistance to gentamycin and its close structural derivatives only, whereas genes encoding AAC(3)-III and AAC(3)-IV enzymes have a broad substrate range, modifying kanamycins, tobramycin, neomycin and paromomycin [1, 2]. Genes encoding AAC(3)-III and AAC(3)-IV enzymes were expressed in plants and shown to confer resistance to gentamicin, kanamycin (one of the genes), and possibly to other antibiotics [3]. Resistance to more than one antibiotic limits the use of the chimeric marker gene. We report that the narrow substrate range AAC(3)-I enzyme from the transposable element Tn21 [2] also provides a useful gentamycin resistance marker in plants. Materials and methods
23 citations