title: Impacts on the metabolome of down-regulating polyphenol oxidase in potato tubers.
abstract: Tubers of potato (Solanum tuberosum L. cv. Estima) genetically modified to reduce polyphenol oxidase (PPO) activity and enzymatic discolouration were assessed for changes in the metabolome using Liquid Chromatography-Mass Spectrometry (LC-MS) and Gas Chromatography (GC)-MS. Metabolome changes induced over a 48 hour (h) period by tuber wounding (sliced transverse sections) were also assessed using two PPO antisense lines (asPPO) and a wild-type (WT) control. Data were analysed using Principal Components Analysis and Analysis of Variance to assess differences between genotypes and temporal changes post-tuber wounding (by slicing). The levels of 15 metabolites (out of a total of 134 that were detected) differed between the WT and asPPO lines in mature tubers at harvest. A considerably higher number (63) of these metabolites changed significantly over a 48 h period following tuber wounding. For individual metabolites the magnitude of the differences between the WT and asPPO lines at harvest were small compared with the impacts of tuber wounding on metabolite levels. Some of the observed metabolite changes are explicable in terms of pathways known to be affected by wound responses. Whilst some statistically significant interactions (11 metabolites) were observed between line and time after wounding, very few profiles were consistent when comparing the WT with both asPPO lines, and the underlying metabolites appeared to be random in terms of the pathways they occupy. Overall, mechanical damage to tubers has a considerably greater impact on the metabolite profile than any potential unintended effects resulting from the down-regulation of PPO gene expression.
authors.affiliation: Environmental and Biochemical Sciences Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, Scotland, UK, louise.shepherd@hutton.ac.uk.
authors.forename: Louise Vida Traill
authors.initials: LV
authors.lastname: Shepherd
authors.forename: Colin James
authors.initials: CJ
authors.lastname: Alexander
authors.forename: Christine Anne
authors.initials: CA
authors.lastname: Hackett
authors.forename: Diane
authors.initials: D
authors.lastname: McRae
authors.forename: Julia Anne
authors.initials: JA
authors.lastname: Sungurtas
authors.forename: Susan Ramsay
authors.initials: SR
authors.lastname: Verrall
authors.forename: Jennifer Anne
authors.initials: JA
authors.lastname: Morris
authors.forename: Peter Edward
authors.initials: PE
authors.lastname: Hedley
authors.forename: David
authors.initials: D
authors.lastname: Rockhold
authors.forename: William
authors.initials: W
authors.lastname: Belknap
authors.forename: Howard Vivian
authors.initials: HV
authors.lastname: Davies
mesh_terms: D000704:Analysis of Variance; D004156:Catechol Oxidase / Q000235:genetics / Q000378:metabolism*; D002853:Chromatography, Liquid / Q000379:methods; D003116:Color; D015536:Down-Regulation; D008401:Gas Chromatography-Mass Spectrometry; D018506:Gene Expression Regulation, Plant; D055442:Metabolome; D020319:Oligodeoxyribonucleotides, Antisense; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D035281:Plant Tubers / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011198:Solanum tuberosum / Q000235:genetics* / Q000378:metabolism*
chemical_list: D020319:Oligodeoxyribonucleotides, Antisense; D010940:Plant Proteins; D004156:Catechol Oxidase