Expression of asparagine synthetase in response to carbohydrate supply in model callus cultures and shoot tips of asparagus (Asparagus officinalis L.)

Irving, Donald E., Shingleton, Glen J. and Hurst, Paul L. (2001) Expression of asparagine synthetase in response to carbohydrate supply in model callus cultures and shoot tips of asparagus (Asparagus officinalis L.). Journal of Plant Physiology, 158 5: 561-568. doi:10.1078/0176-1617-00312


Author Irving, Donald E.
Shingleton, Glen J.
Hurst, Paul L.
Title Expression of asparagine synthetase in response to carbohydrate supply in model callus cultures and shoot tips of asparagus (Asparagus officinalis L.)
Journal name Journal of Plant Physiology   Check publisher's open access policy
ISSN 0176-1617
Publication date 2001
Sub-type Article (original research)
DOI 10.1078/0176-1617-00312
Volume 158
Issue 5
Start page 561
End page 568
Total pages 8
Editor C. Wilhelm
Place of publication Jena, Germany
Publisher Elsevier
Collection year 2001
Language eng
Subject C1
270402 Plant Physiology
620208 Vegetables
Abstract Sugar uptake and metabolism were studied in callus cultures and shoot tips of asparagus. Asparagus callus cultures were used to model senescence in shoot tips. Callus cultures absorbed glucose from a nutrient medium, and accumulated sucrose, glucose and fructose. This uptake of glucose by the callus cultures down-regulated expression of asparagine synthetase and beta -galactosidase transcripts that otherwise accumulated when sugar was withheld. When 80 mm-long asparagus shoots were excised from growing plants and placed in 2% and 8% sucrose solutions, endogenous concentrations of sucrose, glucose, fructose, UDPglucose, and glucose-6-phosphate declined in the 30mm-long meristematic tip regions. At the same time, asparagine and asparagine synthetase gene transcripts began to accumulate in these tips. When 10 mm-long asparagus shoot tips were placed on glucose- or fructose-containing agar, the tips accumulated sucrose, glucose and fructose, and asparagine accumulation and expression of asparagine synthetase were marginally reduced. We concluded that in callus cultures, asparagine synthetase expression was sugar regulated, but that sugar regulation was not as pronounced in asparagus shoot tips. This may be due in part to slower rates of sugar uptake into shoot tips and in part to compartmentation of sugars in the tips. We suggest that callus cultures are not a suitable model for metabolic studies in asparagus shoot tips.
Keyword Asparagus Officinalis L.
Asparagine Synthetase
Gene Regulation
Phosphorylated Metabolites
Senescence
Plant Sciences
Gene-expression
Physiological-changes
Metabolic-regulation
Sucrose Synthase
Higher-plants
Spear Tips
Harvest
Cucumber
Identification
Germination
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Agriculture and Food Sciences
 
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Created: Tue, 14 Aug 2007, 16:35:13 EST