title: Transcriptome analysis suggests that starch synthesis may proceed via multiple metabolic routes in high yielding potato cultivars.
abstract: BACKGROUND
  Glucose-6-phosphate is imported into the amyloplast of potato tubers and thought to constitute the precursor for starch synthesis in potato tubers. However, recently it was shown that glucose-1-phosphate can also be imported into the amyloplast and incorporated into starch via an ATP independent mechanism under special conditions. Nonetheless, glucose-6-phosphate is believed to be the quantitatively important precursor for starch synthesis in potato.
  
  
  RESULTS
  Potato tubers of the high yielding cv Kuras had low gene expression of plastidial phophoglucomutase (PGM) and normal levels of transcripts for other enzymes involved in starch metabolism in comparison with medium and low yielding cultivars as determined by DeepSAGE transcriptome profiling. The decrease in PGM activity in Kuras was confirmed by measuring the enzyme activity from potato tuber extracts. Contrary to expectations, this combination lead to a higher level of intracellular glucose-1-phosphate (G1P) in Kuras suggesting that G1P is directly imported into plastids and can be quantitatively important for starch synthesis under normal conditions in high yielding cultivars.
  
  
  CONCLUSIONS
  This could open entirely new possibilities for metabolic engineering of the starch metabolism in potato via the so far uncharacterized G1P transporter. The perspectives are to increase yield and space efficiency of this important crop. In the light of the increasing demands imposed on agriculture to support a growing global population this presents an exciting new possibility.
authors.affiliation: Department of Agroecology, Aarhus University, Aarhus, Denmark.
authors.forename: Kacper Piotr
authors.initials: KP
authors.lastname: Kaminski
authors.forename: Annabeth Høgh
authors.initials: AH
authors.lastname: Petersen
authors.forename: Mads
authors.initials: M
authors.lastname: Sønderkær
authors.forename: Lars Haastrup
authors.initials: LH
authors.lastname: Pedersen
authors.forename: Henrik
authors.initials: H
authors.lastname: Pedersen
authors.forename: Christian
authors.initials: C
authors.lastname: Feder
authors.forename: Kåre L
authors.initials: KL
authors.lastname: Nielsen
mesh_terms: D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D020869:Gene Expression Profiling; D019298:Glucose-6-Phosphate / Q000378:metabolism; D005958:Glucosephosphates / Q000378:metabolism; D006601:Hexoses / Q000737:chemistry / Q000378:metabolism; D006836:Hydro-Lyases / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism; D018087:Plastids / Q000201:enzymology / Q000378:metabolism; D011198:Solanum tuberosum / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D013213:Starch / Q000096:biosynthesis*; D013395:Sucrose / Q000737:chemistry / Q000378:metabolism
chemical_list: D005958:Glucosephosphates; D006601:Hexoses; D019298:Glucose-6-Phosphate; D013395:Sucrose; D013213:Starch; C031590:glucose-1-phosphate; D006836:Hydro-Lyases; C022362:phosphogluconate dehydratase