Resistance to Acetohydroxamate Acquired by Slow Adaptive Increases in Urease in Cultured Tobacco Cells

Yamaya, Tomoyuki; Filner, Philip

doi:10.1104/pp.67.6.1133

Cited by 19 publications

(4 citation statements)

References 27 publications

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“…This continual increase in tolerance with prolonged culture in the presence of PEG is reflective of an adaptive process rather than of selection, where one would expect a discon tinuous shift in the tolerance of the cells. Similar observations in volving adaptation have been made for cytokinin habituation (28), as well as for growth in a medium using urea as the source of N, a process involving changes in urease activity (36,41).…”

Section: Cell Variantssupporting

confidence: 70%

Cellular Mechanisms Of Tolerance To Water Stress

Hasegawa

Bressan

Handa

et al. 1984

horts

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Water availability is one of the principal environmental limitations of crop productivity throughout the world. The water deficits, which are a consequence of either continuous or transitory periods of drought, cause significant yield reductions on presently cultivated land, and greatly restrict the cultivation of crops on over one-third of the earth’s land surface considered to be arid or semiarid (25). These restrictions on yield potential are rapidly becom ing of great concern in the face of the food demands of an ever increasing world population. The problem becomes complicated further by the fact that supplies of suitable irrigation water are dwindling rapidly, and that the costs of irrigation are becoming prohibitive. As a result, studies on the effects of water stress on plant survival and yield are attracting added interest in plant science research.

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Section: Cell Variantssupporting

confidence: 70%

Cellular Mechanisms Of Tolerance To Water Stress

Hasegawa

Bressan

Handa

et al. 1984

horts

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“…It is not certain to what extent the culture environment, including NaCl, directs any stable genomic alterations (Skokut and Filner 1980;Yamaya and Filner 1981;Handa et al 1983;Meins 1983;Donn et al 1984;Cullis and Cleary 1985;Lee and Phillips 1988;Brettell and Dennis 1991) that would enhance salt tolerance. The establishment of the stable NaCI-tolerant phenotype is accompanied by a stable, albeit polyploid, chromosome complement (Kononowicz et al 1990a, b) and the capacity for increased expression of genes whose products are presumed to be of adaptive benefit to the cells Perez-Prat et al 1990;Narasimhan et al 1991).…”

Section: Somatic Cell Selectionmentioning

confidence: 97%

Tissue Culture in the Improvement of Salt Tolerance in Plants

Hasegawa¹,

Bressan²,

Nelson³

et al. 1994

Monographs on Theoretical and Applied Genetics

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“…The overproduction of enzymes required for growth has been observed in inhibitor-resistant lines of both mammalian (1,10) and plant (3,19) cells. In the case of the mammalian cells, the increases were due to gene amplification.…”

mentioning

confidence: 99%

Selection and Characterization of a Carrot Cell Line Tolerant to Glyphosate

et al. 1984

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Cultured carrot (Daucs carota L.) cells were adapted to growing in 25 millimolar glyphosate by transfer into progressively higher concentrations ofthe herbicide. Tolerance was increased 52-fold, and the adaptation was stable in the absence of glyphosate. The uptake of glyphosate was similar for adapted and nonadapted cells. Activity of the enzyme 5-enolpyruvylshikimic acid-3-phosphate synthase was 12-fold higher in the adapted line compared to nonadapted cells, while activities of shikimate dehydrogenase and anthranilate synthase were similr in the two cell types. The adapted cells had higher levels of free amino acids-especially threonine, methionine, tyrosine, phenylalanine, tryptophan, histidine, and arginine than did nonadapted cells. Glyphosate treatment caused decreases of 50 to 65% in the levels of serine, glycine, methionine, tyrosine, phenybaanine, and tryptophan in nonadapted cells, but caused little change in free amino acid levels in adapted cells.The adaptation reported here supports the growing body of evidence linking tolerance to glyphosate with increased levels of the enzyme 5-enolpyruvylshikimic acid-3-phosphate synthase. The elevated levels of aromatic amino acids, which may confer resistance in adapted cells, suggest that control of the shikimate pathway may be altered in these cells.The overproduction of enzymes required for growth has been observed in inhibitor-resistant lines of both mammalian (1, 10) and plant (3, 19) cells. In the case of the mammalian cells, the increases were due to gene amplification. The shikimic acid pathway enyme EPSP2 synthase has been found to be strongly inhibited by the broad-spectrum herbicide glyphosate (N-[phosphonomethyl]glycine) (15), and adaptation of plant cells to this herbicide has been accompanied by large increases in the extractable activity of this enzyme (3).While higher levels of EPSP synthase activity have been reported for cells growing in glyphosate, the effect of this change on levels of aromatic amino acids has not been reported. Glyphosate Uptake. Two g of cells in log phase were transferred into 100 ml medium containing 910 cpm/ml of (methyl-'4C) glyphosate and a total glyphosate concentration of0.25 mm.Three replicate flasks were used for each cell type. At 1, 2, 4, 8, 24, and 48 hr after transfer, 10-ml aliquots were taken and cells were collected on Miracloth. After washing three times with 5 ml of medium containing 0.25 mM unlabeled glyphosate, cells were weighed and dispersed in gel formed by adding 4 ml H20 and 15 ml Aquasol. Radioactivity was determined with a Packard scintillation spectrometer.Amino Acids. Five g of cells in early stationary phase (10 d after transfer) were inoculated into 100 ml fresh medium in 250-ml flasks. Four

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Resistance to Acetohydroxamate Acquired by Slow Adaptive Increases in Urease in Cultured Tobacco Cells

Abstract: Urease activty of tobacco XD cells (1U cells) had undergone a 4-fold increase (4U cells) during a year of growth on urea (Skokut and Filner 1980 Plant Phvsiol 65: 995-1003

Cited by 19 publications

References 27 publications

Cellular Mechanisms Of Tolerance To Water Stress

Cellular Mechanisms Of Tolerance To Water Stress

Tissue Culture in the Improvement of Salt Tolerance in Plants

Selection and Characterization of a Carrot Cell Line Tolerant to Glyphosate

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