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At the nonpermissive temperature, somatic embryogenesis of the temperature-sensitive (ts) carrot cell mutant ts11 does not proceed beyond the globular stage. This developmental arrest can be lifted by the addition of proteins secreted by wild-type cells to the culture medium. From this mixture of secreted proteins, a 32-kD glycoprotein, designated(More)
The level of auxin - both natural and synthetic — in the medium has a strong effect on the level of 5-methyl-cytosine in the DNA of carrot cells in culture. This level may vary from approximately 15% to 70% of total cytosine without apparent effects on growth rate and cell morphology. No effect was seen with cytokinin. During somatic embryogenesis, in the(More)
High concentrations of cytokinins block cell proliferation and induce programmed cell death (PCD) in both carrot (Daucus carota L.) and Arabidopsis thaliana (L.) Heynh. cell cultures [13 and 27 µM N6-benzylaminopurine (BAP), respectively]. In the present work, cell death was scored by Evan's blue staining and was also demonstrated to be programmed by(More)
Embryogenic cell lines with lasting embryogenic potential can be obtained from somatic embryos induced directly from zygotic embryos of Arabidopsis thaliana, ecotype Columbia. The response to a critical concentration of auxin, which seems to be the all-important factor in the generation of embryogenic cell lines, is exhibited by somatic embryos but not by(More)
In this report, we show that nitric oxide affects mitochondrial functionality in plant cells and reduces total cell respiration due to strong inhibition of the cytochrome pathway. The residual respiration depends on the alternative pathway and novel synthesis of alternative oxidase occurs. These modifications are associated with depolarisation of the(More)
Potassium is an essential nutrient which plays an important role in many aspects of plant growth and development. Plants have developed a number of highly specific mechanisms to take up potassium from the soil; these include the expression of K(+) transporters and potassium channels in root cells. Despite the fact that root epidermal and hair cells are in(More)
Programmed cell death (apoptosis) in plants - and plant cells in culture - has received much less attention than its animal counterpart. In the present work, using agents producing biotic or abiotic stress on cultivated cells from carrot - and, in a few experiments, Arabidopsis -, we show that DNA fragmentation, random or oligonucleosomal, can be induced by(More)
An easy method is presented for the purification of the different stages of carrot embryoids. This is based on a synchronization of the regenerating culture and on a filtration through filters of various pore sizes. A differential sedimentation was used for removing undifferentiated cells. At the end of the process, the different stages: globular, heart-(More)
During the establishment of an embryogenic cell line from a carrot hypocotyl explant, processes closely resembling meiotic divisions are seen. A microdensitometric analysis revealed that the amount of cellular DNA diminished in the majority of cells to the haploid level. However, the diploid level was re-established in a matter of a few days. The genetic(More)