title: Effect of down-regulation of ethylene biosynthesis on fruit flavor complex in apple fruit.
abstract: The role of ethylene in regulating sugar, acid, texture and volatile components of fruit quality was investigated in transgenic apple fruit modified in their capacity to synthesize endogenous ethylene. Fruit obtained from plants silenced for either ACS (ACC synthase; ACC-1-aminocyclopropane-1-carboxylic acid) or ACO (ACC oxidase), key enzymes responsible for ethylene biosynthesis, expectedly showed reduced autocatalytic ethylene production. Ethylene suppressed fruits were significantly firmer than controls and displayed an increased shelf-life. No significant difference was observed in sugar or acid accumulation suggesting that sugar and acid composition and accumulation is not directly under ethylene control. Interestingly, a significant and dramatic suppression of the synthesis of volatile esters was observed in fruit silenced for ethylene. However, no significant suppression was observed for the aldehyde and alcohol precursors of these esters. Our results indicate that ethylene differentially regulates fruit quality components and the availability of these transgenic apple trees provides a unique resource to define the role of ethylene and other factors that regulate fruit development.
authors.affiliation: Department of Pomology, University of California, I Shields Ave., Davis, CA 95616, USA. amdandekar@ucdavis.edu
authors.forename: Abhaya M
authors.initials: AM
authors.lastname: Dandekari
authors.forename: Gianni
authors.initials: G
authors.lastname: Teo
authors.forename: Bruno G
authors.initials: BG
authors.lastname: Defilippi
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Uratsu
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Passey
authors.forename: Adel A
authors.initials: AA
authors.lastname: Kader
authors.forename: John R
authors.initials: JR
authors.lastname: Stow
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Colgan
authors.forename: David J
authors.initials: DJ
authors.lastname: James
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000235:genetics*; D005030:Ethylenes / Q000096:biosynthesis*; D005638:Fruit; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D006801:Humans; D008190:Lyases / Q000235:genetics*; D027845:Malus / Q000201:enzymology / Q000235:genetics*; D010937:Plant Growth Regulators / Q000096:biosynthesis*; D013649:Taste
chemical_list: D005030:Ethylenes; D010937:Plant Growth Regulators; C036216:ethylene; D000594:Amino Acid Oxidoreductases; C059460:1-aminocyclopropane-1-carboxylic acid oxidase; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase