Physiological responses of wild type and putrescine-overproducing transgenic cells of poplar to variations in the form and concentration of nitrogen in the medium
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Tree Physiology. 24: 551-560.
We determined: (a) the physiological consequences of overproduction of putrescine in transgenic poplar (Populus nigra x mnrimoviczir) cells expressing an omithine decarboxylase transgene; and (b) effects of variation in nitrogen (N) concentration of the medium on cellular polyamine concentration in transgenic and non-transgenic cells. Cells grown in the presence of supplemental (to the normal concentrations of N sources in the growth medium) and reduced amounts of NH4N03 and KN03 were used to study effects on membrane permeability, mitochondria1 respiratory activity, protein accumulation, growth rates and changes in cellular polyamine concentration. The N concentration of the MS medium was not a limiting factor for continued overproduction of putrescine in transgenic cells. However, continued supplies of NH4 and NO3 were required to maintain homeostatic amounts of putrescine in both cell lines. The presence of high amounts of putrescine in transgenic cells had significant effects on the physiological parameters measured. Compared with nontransgenic cells, transgenic cells had greater plasma membrane permeability, less tolerance to NH4NO3, more tolerance to KNO3, and accumulated higher amounts of soluble protein.
Keywordsammonia cell viability, mitochondria1 activity, nitrate, ornithine decarboxylase, polyamines, spermidine, spermine
Minocha, Rakesh; Lee, Jae Soon; Long, Stephanie; Bhatnagar, Pratiksha; Minocha, Subhash C. 2004. Physiological responses of wild type and putrescine-overproducing transgenic cells of poplar to variations in the form and concentration of nitrogen in the medium. Tree Physiology. 24: 551-560.