Studies on the photosynthesis-inhibiting herbicide resistance of photoautotrophically cultured tobacco cells

研究了不同主要作用方式的除草剂对烟草细胞光自养、光异养、异养培养的生长影响。这些反应与烟草幼苗对相同除草剂的反应进行了比较。与光养和异养细胞（阿特拉津、迪乌隆、百草枯）相比，主要抑制或干扰光合作用的除草剂对光自养细胞的生长抑制最为强烈。除抑制光合作用外，具有主要作用模式的除草剂在相似浓度下（2,4- d、苯胺、草甘膦、甲胺磷、氯酸钠、双磷、DTP）抑制所有类型培养细胞的生长。除氯酸钠外，光自养细胞对各种除草剂最敏感。此外，光自养细胞对大多数除草剂和幼苗一样有反应，除了草甘膦和苯丙咪唑。结果表明，光自养培养细胞是体外研究除草剂作用最适宜的系统。基于上述信息，从培养的光自养烟草细胞中通过反复暴露于有毒水平的除草剂阿特拉津，选择了一株对抑制光合作用的除草剂阿特拉津具有抗性的变异细胞系。抗性细胞系显示叶绿体psbA基因有一个点突变。此外，在没有持续的选择压力的情况下，这种突变随后被淘汰。这说明光自养细胞培养可用于叶绿体基因组的基因工程。

The effects of herbicides with different primary modes of action were examined on the growth of photoautotrophic, photomixotrophic, heterotrophic cultures of tobacco cells. These responses were compared with those of tobacco seedlings to the same herbicides. Herbicides , which primarily inhibit or disturb photosynthetic processes, suppressed the growth of photoautotrophic cells most strongly, as compared to photomixotrophic and heterotrophic cells (atrazine, diuron, paraquat). Herbicides having a primary mode of action other than the inhibition of photosynthetic processes, suppressed the growth of all type of cultured cells at similar concentration (2,4-D, diphenamid, glyphosate, dinoseb, sodium chlorate, bialaphos, DTP). Photoautotrophic cells were the most sensitive cultured cell lines to all kinds of herbicides except sodium chlorate. Furthermore, photoautotrophic cells responded to most of the herbicides as did the seedlings, with the exception of glyphosate and diphenamid. It was concluded that photoautotrophically cultured cells would be the most suitable system to study the effects of herbicides in vitro.Based on the above information, a variant cell line showing resistance to the photosynthesis-inhibiting hervicide atrazine was selected from cultured photoautotrophic tobacco cells by repeated exposure to toxic levels of the herbicide. The resistant cell line was shown to have a point mutation in the chloroplast psbA gene. Furthermore, this mutation subsequently was stavle in the absence of continued selection pressure. This demonstrate that photoautotrophic cell culture can be used for genetic engineering of the chloroplast genome.