Antibiotic resistance in Nicotiana.

The mode of action, and mechanism of resistance of many antibiotics are known since antibiotic resistance markers are commonly used in microbial genetics. Some of them, such as streptomycin, kanamycin and chloramphenicol selectively inhibit protein synthesis on the ''bacterial type'' ribosomes of the chloroplasts and mitochondria. Resistance to these antibiotics is, in some cases, coded by the organellar DNA, so these mutations are convenient markers in studies on organelle segregation, recombination and function in fungi and a 1 gae 1 The need for marker mutations in plant cell genetics, and our interest in cytoplasmic organelles, suggested to us the selection of antibiotic resistant cell lines in cell cultures of two species belonging to the genus Nicotiana~ N. tabacum and N. sylvestris. Streptomycin, kanamycin and chloramphenicol resistant lines described in flowering plants (N. tabacum~ N. sylvestris~ Petunia hybrida) and the moss, Physcomitrella patens~ have been reviewed. In the next sections some recent results on streptomycin, chloramphenicol and kanamycin resistance from our laboratory will follow

Antibiotic resistance in Nicotiana.

The mode of action, and mechanism of resistance of many antibiotics are known since antibiotic resistance markers are commonly used in microbial genetics. Some of them, such as streptomycin, kanamycin and chloramphenicol selectively inhibit protein synthesis on the ''bacterial type'' ribosomes of the chloroplasts and mitochondria. Resistance to these antibiotics is, in some cases, coded by the organellar DNA, so these mutations are convenient markers in studies on organelle segregation, recombination and function in fungi and a 1 gae 1 The need for marker mutations in plant cell genetics, and our interest in cytoplasmic organelles, suggested to us the selection of antibiotic resistant cell lines in cell cultures of two species belonging to the genus Nicotiana~ N. tabacum and N. sylvestris. Streptomycin, kanamycin and chloramphenicol resistant lines described in flowering plants (N. tabacum~ N. sylvestris~ Petunia hybrida) and the moss, Physcomitrella patens~ have been reviewed. In the next sections some recent results on streptomycin, chloramphenicol and kanamycin resistance from our laboratory will follow

A cell line of Nicotiana sylvestris with resistance to kanamycin and streptomycin

Cell lines resistant to 50 gg ml- 1 kanamycin sulphate were isolated from cell suspension cultures initiated from a haploid Nicotiana sylvestris plant. One line, KR103, has been studied in detail. Resistance of this line was shown to be stable in the absence of the drug. KR103 was found also to be resistant to streptomycin, another inhibitor of 70S ribosomal protein synthesis. Both KR103 and the sensitive line convert kanamycin, but not streptomycin, to a form which is no longer effective in a bacterial bioassay, while maintaining its toxicity for sensitive plant cells. KR103 is defective in morphogenesis and plastid development

A cell line of Nicotiana sylvestris with resistance to kanamycin and streptomycin

Cell lines resistant to 50 gg ml- 1 kanamycin sulphate were isolated from cell suspension cultures initiated from a haploid Nicotiana sylvestris plant. One line, KR103, has been studied in detail. Resistance of this line was shown to be stable in the absence of the drug. KR103 was found also to be resistant to streptomycin, another inhibitor of 70S ribosomal protein synthesis. Both KR103 and the sensitive line convert kanamycin, but not streptomycin, to a form which is no longer effective in a bacterial bioassay, while maintaining its toxicity for sensitive plant cells. KR103 is defective in morphogenesis and plastid development

Autoluminescent Plants

Prospects of obtaining plants glowing in the dark have captivated the imagination of scientists and layman alike. While light emission has been developed into a useful marker of gene expression, bioluminescence in plants remained dependent on externally supplied substrate. Evolutionary conservation of the prokaryotic gene expression machinery enabled expression of the six genes of the lux operon in chloroplasts yielding plants that are capable of autonomous light emission. This work demonstrates that complex metabolic pathways of prokaryotes can be reconstructed and function in plant chloroplasts and that transplastomic plants can emit light that is visible by naked eye