title: Production of high-starch, low-glucose potatoes through over-expression of the metabolic regulator SnRK1.
abstract: Transgenic potato (Solanum tuberosum cv. Prairie) lines were produced over-expressing a sucrose non-fermenting-1-related protein kinase-1 gene (SnRK1) under the control of a patatin (tuber-specific) promoter. SnRK1 activity in the tubers of three independent transgenic lines was increased by 55%-167% compared with that in the wild-type. Glucose levels were decreased, at 17%-56% of the levels of the wild-type, and the starch content showed an increase of 23%-30%. Sucrose and fructose levels in the tubers of the transgenic plants did not show a significant change. Northern analyses of genes encoding sucrose synthase and ADP-glucose pyrophosphorylase, two key enzymes involved in the biosynthetic pathway from sucrose to starch, showed that the expression of both was increased in tubers of the transgenic lines compared with the wild-type. In contrast, the expression of genes encoding two other enzymes of carbohydrate metabolism, alpha-amylase and sucrose phosphate synthase, showed no change. The activity of sucrose synthase and ADP-glucose pyrophosphorylase was also increased, by approximately 20%-60% and three- to five-fold, respectively, whereas the activity of hexokinase was unchanged. The results are consistent with a role for SnRK1 in regulating carbon flux through the storage pathway to starch biosynthesis. They emphasize the importance of SnRK1 in the regulation of carbohydrate metabolism and resource partitioning, and indicate a specific role for SnRK1 in the control of starch accumulation in potato tubers.
authors.affiliation: Long Ashton Research Station, Bristol BS41 9AF, UK.
authors.forename: Rowan S
authors.initials: RS
authors.lastname: McKibbin
authors.forename: Nira
authors.initials: N
authors.lastname: Muttucumaru
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Paul
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Powers
authors.forename: Michael M
authors.initials: MM
authors.lastname: Burrell
authors.forename: Steve
authors.initials: S
authors.lastname: Coates
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Purcell
authors.forename: Axel
authors.initials: A
authors.lastname: Tiessen
authors.forename: Peter
authors.initials: P
authors.lastname: Geigenberger
authors.forename: Nigel G
authors.initials: NG
authors.lastname: Halford
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000235:genetics; D005632:Fructose / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005947:Glucose / Q000235:genetics / Q000378:metabolism*; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011198:Solanum tuberosum / Q000235:genetics*; D013213:Starch / Q000235:genetics / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; C043222:patatin protein, Solanum tuberosum; D005632:Fructose; D013395:Sucrose; D013213:Starch; D005964:Glucosyltransferases; C022699:sucrose synthase; C022698:sucrose-phosphate synthase; D011494:Protein Kinases; D006593:Hexokinase; D051599:Glucose-1-Phosphate Adenylyltransferase; D002265:Carboxylic Ester Hydrolases; D000516:alpha-Amylases; D005947:Glucose