title: Engineering the expression level of cytosolic nucleoside diphosphate kinase in transgenic Solanum tuberosum roots alters growth, respiration and carbon metabolism.
abstract: Nucleoside diphosphate kinase (NDPK) is a ubiquitous enzyme that catalyzes the transfer of the γ-phosphate from a donor nucleoside triphosphate to an acceptor nucleoside diphosphate. In this study we used a targeted metabolomic approach and measurement of physiological parameters to report the effects of the genetic manipulation of cytosolic NDPK (NDPK1) expression on physiology and carbon metabolism in potato (Solanum tuberosum) roots. Sense and antisense NDPK1 constructs were introduced in potato using Agrobacterium rhizogenes to generate a population of root clones displaying a 40-fold difference in NDPK activity. Root growth, O2uptake, flux of carbon between sucrose and CO2, levels of reactive oxygen species and some tricarboxylic acid cycle intermediates were positively correlated with levels of NDPK1 expression. In addition, NDPK1 levels positively affected UDP-glucose and cellulose contents. The activation state of ADP-glucose pyrophosphorylase, a key enzyme in starch synthesis, was higher in antisense roots than in roots overexpressing NDPK1. Further analyses demonstrated that ADP-glucose pyrophosphorylase was more oxidized, and therefore less active, in sense clones than antisense clones. Consequently, antisense NDPK1 roots accumulated more starch and the starch to cellulose ratio was negatively affected by the level of NDPK1. These data support the idea that modulation of NDPK1 affects the distribution of carbon between starch and cellulose biosynthetic pathways.
authors.affiliation: Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke Est, Montréal, QC, H1X 2B2, Canada.
authors.forename: Sonia
authors.initials: S
authors.lastname: Dorion
authors.affiliation: Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke Est, Montréal, QC, H1X 2B2, Canada.
authors.forename: Audrey
authors.initials: A
authors.lastname: Clendenning
authors.affiliation: Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke Est, Montréal, QC, H1X 2B2, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Rivoal
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002952:Citric Acid Cycle / Q000235:genetics / Q000502:physiology; D003600:Cytosol / Q000378:metabolism*; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D009701:Nucleoside-Diphosphate Kinase / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D011198:Solanum tuberosum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D013395:Sucrose; D002244:Carbon; D009701:Nucleoside-Diphosphate Kinase; D051599:Glucose-1-Phosphate Adenylyltransferase
keywords: 
  Solanum tuberosum
  ; ADP-glucose pyrophosphorylase; carbon metabolism; cellulose; glycolytic flux; nucleoside diphosphate kinase; reactive oxygen species; respiration; root; starch