title: The sub-cellular localisation of the potato (Solanum tuberosum L.) carotenoid biosynthetic enzymes, CrtRb2 and PSY2.
abstract: Carotenoids are isoprenoids with important biological roles both for plants and animals. The yellow flesh colour of potato (Solanum tuberosum L.) tubers is a quality trait dependent on the types and levels of carotenoids that accumulate. The carotenoid biosynthetic pathway is well characterised, facilitating the successful engineering of carotenoid content in numerous crops including potato. However, a clear understanding concerning the factors regulating carotenoid accumulation and localisation in plant storage organs, such as tubers, is lacking. In the present study, the localisation of key carotenoid biosynthetic enzymes was investigated, as one of the unexplored factors that could influence the accumulation of carotenoids in potato tubers. Stable transgenic potato plants were generated by over-expressing β-CAROTENE HYDROXYLASE 2 (CrtRb2) and PHYTOENE SYNTHASE 2 (PSY2) genes, fused to red fluorescent protein (RFP). Gene expression and carotenoid levels were both significantly increased, confirming functionality of the fluorescently tagged proteins. Confocal microscopy studies revealed different sub-organellar localisations of CrtRb2-RFP and PSY2-RFP within amyloplasts. CrtRb2 was detected in small vesicular structures, inside amyloplasts, whereas PSY2 was localised in the stroma of amyloplasts. We conclude that it is important to consider the location of biosynthetic enzymes when engineering the carotenoid metabolic pathway in storage organs such as tubers.
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Stefania
authors.initials: S
authors.lastname: Pasare
authors.forename: Kathryn
authors.initials: K
authors.lastname: Wright
authors.forename: Raymond
authors.initials: R
authors.lastname: Campbell
authors.forename: Wayne
authors.initials: W
authors.lastname: Morris
authors.forename: Laurence
authors.initials: L
authors.lastname: Ducreux
authors.forename: Sean
authors.initials: S
authors.lastname: Chapman
authors.forename: Peter
authors.initials: P
authors.lastname: Bramley
authors.forename: Paul
authors.initials: P
authors.lastname: Fraser
authors.forename: Alison
authors.initials: A
authors.lastname: Roberts
authors.forename: Mark
authors.initials: M
authors.lastname: Taylor
mesh_terms: D000595:Amino Acid Sequence; D002338:Carotenoids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D005822:Genetic Vectors / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000201:enzymology; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D035281:Plant Tubers / Q000235:genetics; D030821:Plants, Genetically Modified; D021381:Protein Transport; D011198:Solanum tuberosum / Q000201:enzymology*; D013347:Subcellular Fractions / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics
chemical_list: D010940:Plant Proteins; D049452:Green Fluorescent Proteins; D002338:Carotenoids