title: Phenotypic changes associated with RNA interference silencing of chalcone synthase in apple (Malus × domestica).
abstract: We have identified in apple (Malus × domestica) three chalcone synthase (CHS) genes. In order to understand the functional redundancy of this gene family RNA interference knockout lines were generated where all three of these genes were down-regulated. These lines had no detectable anthocyanins and radically reduced concentrations of dihydrochalcones and flavonoids. Surprisingly, down-regulation of CHS also led to major changes in plant development, resulting in plants with shortened internode lengths, smaller leaves and a greatly reduced growth rate. Microscopic analysis revealed that these phenotypic changes extended down to the cellular level, with CHS-silenced lines showing aberrant cellular organisation in the leaves. Fruit collected from one CHS-silenced line was smaller than the 'Royal Gala' controls, lacked flavonoids in the skin and flesh and also had changes in cell morphology. Auxin transport experiments showed increased rates of auxin transport in a CHS-silenced line compared with the 'Royal Gala' control. As flavonoids are well known to be key modulators of auxin transport, we hypothesise that the removal of almost all flavonoids from the plant by CHS silencing creates a vastly altered environment for auxin transport to occur and results in the observed changes in growth and development.
authors: The New Zealand Institute for Plant and Food Research Ltd, Private Bag 92169, Auckland 1141, New Zealand. adare@plantandfood.co.nz
authors: Andrew P
authors: AP
authors: Dare
authors: Sumathi
authors: S
authors: Tomes
authors: Midori
authors: M
authors: Jones
authors: Tony K
authors: TK
authors: McGhie
authors: David E
authors: DE
authors: Stevenson
authors: Ross A
authors: RA
authors: Johnson
authors: David R
authors: DR
authors: Greenwood
authors: Roger P
authors: RP
authors: Hellens
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D048430:Cell Shape; D047188:Chalcones / Q000378:metabolism; D004789:Enzyme Activation; D044950:Flavanones; D005638:Fruit / Q000033:anatomy & histology / Q000201:enzymology / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D007210:Indoleacetic Acids / Q000378:metabolism; D027845:Malus / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics; D010641:Phenotype; D010695:Phlorhizin; D059828:Plant Cells / Q000201:enzymology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D034622:RNA Interference
chemical_list: D047188:Chalcones; D044950:Flavanones; D007210:Indoleacetic Acids; D010940:Plant Proteins; D010695:Phlorhizin; D000217:Acyltransferases; C020141:flavanone synthetase; C015812:dihydrochalcone; C005273:naringenin