title: Altering trehalose-6-phosphate content in transgenic potato tubers affects tuber growth and alters responsiveness to hormones during sprouting.
abstract: Trehalose-6-phosphate (T6P) is a signaling metabolite that regulates carbon metabolism, developmental processes, and growth in plants. In Arabidopsis (Arabidopsis thaliana), T6P signaling is, at least in part, mediated through inhibition of the SNF1-related protein kinase SnRK1. To investigate the role of T6P signaling in a heterotrophic, starch-accumulating storage organ, transgenic potato (Solanum tuberosum) plants with altered T6P levels specifically in their tubers were generated. Transgenic lines with elevated T6P levels (B33-TPS, expressing Escherichia coli osmoregulatory trehalose synthesis A [OtsA], which encodes a T6P synthase) displayed reduced starch content, decreased ATP contents, and increased respiration rate diagnostic for high metabolic activity. On the other hand, lines with significantly reduced T6P (B33-TPP, expressing E. coli OtsB, which encodes a T6P phosphatase) showed accumulation of soluble carbohydrates, hexose phosphates, and ATP, no change in starch when calculated on a fresh weight basis, and a strongly reduced tuber yield. [¹⁴C]glucose feeding to transgenic tubers indicated that carbon partitioning between starch and soluble carbohydrates was not altered. Transcriptional profiling of B33-TPP tubers revealed that target genes of SnRK1 were strongly up-regulated and that T6P inhibited potato tuber SnRK1 activity in vitro. Among the SnRK1 target genes in B33-TPP tubers, those involved in the promotion of cell proliferation and growth were down-regulated, while an inhibitor of cell cycle progression was up-regulated. T6P-accumulating tubers were strongly delayed in sprouting, while those with reduced T6P sprouted earlier than the wild type. Early sprouting of B33-TPP tubers correlated with a reduced abscisic acid content. Collectively, our data indicate that T6P plays an important role for potato tuber growth.
authors.affiliation: Department of Biology, Division of Biochemistry, Friedrich-Alexander-Universität, 91058 Erlangen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Debast
authors.forename: Adriano
authors.initials: A
authors.lastname: Nunes-Nesi
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Hajirezaei
authors.forename: Jörg
authors.initials: J
authors.lastname: Hofmann
authors.forename: Uwe
authors.initials: U
authors.lastname: Sonnewald
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.forename: Frederik
authors.initials: F
authors.lastname: Börnke
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000187:drug effects / Q000235:genetics; D002250:Carbon Radioisotopes; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005819:Genetic Markers; D018525:Germination / Q000187:drug effects* / Q000235:genetics; D005947:Glucose / Q000494:pharmacology; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology*; D035281:Plant Tubers / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D013395:Sucrose / Q000494:pharmacology; D013403:Sugar Phosphates / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014199:Trehalose / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D005819:Genetic Markers; D010937:Plant Growth Regulators; D012333:RNA, Messenger; D013403:Sugar Phosphates; C082722:trehalose-6-phosphate; D013395:Sucrose; D000244:Adenosine Diphosphate; D000040:Abscisic Acid; D000255:Adenosine Triphosphate; D014199:Trehalose; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; D005947:Glucose