title: Pectin engineering to modify product quality in potato.
abstract: Although processed potato tuber texture is an important trait that influences consumer preference, a detailed understanding of tuber textural properties at the molecular level is lacking. Previous work has identified tuber pectin methyl esterase (PME) activity as a potential factor impacting on textural properties, and the expression of a gene encoding an isoform of PME (PEST1) was associated with cooked tuber textural properties. In this study, a transgenic approach was undertaken to investigate further the impact of the PEST1 gene. Antisense and over-expressing potato lines were generated. In over-expressing lines, tuber PME activity was enhanced by up to 2.3-fold; whereas in antisense lines, PME activity was decreased by up to 62%. PME isoform analysis indicated that the PEST1 gene encoded one isoform of PME. Analysis of cell walls from tubers from the over-expressing lines indicated that the changes in PME activity resulted in a decrease in pectin methylation. Analysis of processed tuber texture demonstrated that the reduced level of pectin methylation in the over-expressing transgenic lines was associated with a firmer processed texture. Thus, there is a clear link between PME activity, pectin methylation and processed tuber textural properties.
authors.affiliation: Plant Products and Food Quality Programme, Scottish Crop Research Institute, Dundee, UK.
authors.forename: Heather A
authors.initials: HA
authors.lastname: Ross
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Morris
authors.forename: Laurence J M
authors.initials: LJ
authors.lastname: Ducreux
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hancock
authors.forename: Susan R
authors.initials: SR
authors.lastname: Verrall
authors.forename: Jenny A
authors.initials: JA
authors.lastname: Morris
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Tucker
authors.forename: Derek
authors.initials: D
authors.lastname: Stewart
authors.forename: Pete E
authors.initials: PE
authors.lastname: Hedley
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: McDougall
authors.forename: Mark A
authors.initials: MA
authors.lastname: Taylor
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D004789:Enzyme Activation; D005511:Food Handling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005818:Genetic Engineering / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D007527:Isoenzymes / Q000378:metabolism; D008745:Methylation; D020411:Oligonucleotide Array Sequence Analysis; D010368:Pectins / Q000235:genetics / Q000378:metabolism; D035281:Plant Tubers / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011198:Solanum tuberosum / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D019076:Transgenes
chemical_list: D007527:Isoenzymes; D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase