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Devoghalaere F, Doucen T, Guitton B, Keeling J, Payne W, Ling TJ, Ross JJ, Hallett IC, Gunaseelan K, Dayatilake GA, Diak R, Breen KC, Tustin DS, Costes E, Chagné D, Schaffer RJ, David KM. A genomics approach to understanding the role of auxin in apple (Malus x domestica) fruit size control. BMC Plant Biol 2012; 12:7. [PMID: 22243694 PMCID: PMC3398290 DOI: 10.1186/1471-2229-12-7] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 01/13/2012] [Indexed: 05/18/2023]
Abstract
BACKGROUND Auxin is an important phytohormone for fleshy fruit development, having been shown to be involved in the initial signal for fertilisation, fruit size through the control of cell division and cell expansion, and ripening related events. There is considerable knowledge of auxin-related genes, mostly from work in model species. With the apple genome now available, it is possible to carry out genomics studies on auxin-related genes to identify genes that may play roles in specific stages of apple fruit development. RESULTS High amounts of auxin in the seed compared with the fruit cortex were observed in 'Royal Gala' apples, with amounts increasing through fruit development. Injection of exogenous auxin into developing apples at the start of cell expansion caused an increase in cell size. An expression analysis screen of auxin-related genes involved in auxin reception, homeostasis, and transcriptional regulation showed complex patterns of expression in each class of gene. Two mapping populations were phenotyped for fruit size over multiple seasons, and multiple quantitative trait loci (QTLs) were observed. One QTL mapped to a region containing an Auxin Response Factor (ARF106). This gene is expressed during cell division and cell expansion stages, consistent with a potential role in the control of fruit size. CONCLUSIONS The application of exogenous auxin to apples increased cell expansion, suggesting that endogenous auxin concentrations are at least one of the limiting factors controlling fruit size. The expression analysis of ARF106 linked to a strong QTL for fruit weight suggests that the auxin signal regulating fruit size could partially be modulated through the function of this gene. One class of gene (GH3) removes free auxin by conjugation to amino acids. The lower expression of these GH3 genes during rapid fruit expansion is consistent with the apple maximising auxin concentrations at this point.
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Affiliation(s)
- Fanny Devoghalaere
- The New Zealand Institute for Plant & Food Research Limited (PFR), Private Bag 92169, Auckland 1142, New Zealand
| | - Thomas Doucen
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Baptiste Guitton
- PFR, Private Bag 11600, Palmerston North 4442, New Zealand
- INRA, UMR AGAP, Equipe Architecture et Fonctionnement des Espèces Fruitières, Avenue Agropolis - TA-A-108/03, 34398 Montpellier Cedex 01, France
| | - Jeannette Keeling
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Wendy Payne
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Toby John Ling
- School of Plant Science, University of Tasmania, GPO Box 252-55, Hobart, Tasmania 7001, Australia
| | - John James Ross
- School of Plant Science, University of Tasmania, GPO Box 252-55, Hobart, Tasmania 7001, Australia
| | - Ian Charles Hallett
- The New Zealand Institute for Plant & Food Research Limited (PFR), Private Bag 92169, Auckland 1142, New Zealand
| | - Kularajathevan Gunaseelan
- The New Zealand Institute for Plant & Food Research Limited (PFR), Private Bag 92169, Auckland 1142, New Zealand
| | - GA Dayatilake
- PFR, Private Bag 1401, Havelock North 4157, New Zealand
| | - Robert Diak
- PFR, Old Mill Road, RD3, Motueka 7198, New Zealand
| | - Ken C Breen
- PFR, Private Bag 1401, Havelock North 4157, New Zealand
| | | | - Evelyne Costes
- INRA, UMR AGAP, Equipe Architecture et Fonctionnement des Espèces Fruitières, Avenue Agropolis - TA-A-108/03, 34398 Montpellier Cedex 01, France
| | - David Chagné
- PFR, Private Bag 11600, Palmerston North 4442, New Zealand
| | - Robert James Schaffer
- The New Zealand Institute for Plant & Food Research Limited (PFR), Private Bag 92169, Auckland 1142, New Zealand
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Karine Myriam David
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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