ISHS Acta Horticulturae 800: X International Pear Symposium
INVESTIGATING THE MOLECULAR MECHANISM OF ANTHOCYANIN PRODUCTION IN 'BON ROUGE' PYRUS COMMUNIS L. |
| Authors: | M.G. du Preez, D.J.G. Rees |
| Keywords: | gene expression, proteomics, pigment characterisation, stress response, pear |
| Abstract:
The production and stability of fruit skin colour in red and blush pears are desirable traits in many export cultivars under commercial production in the Western Cape region of South Africa. To investigate the underlying molecular mechanism controlling the production, stability and loss of red pigment, anthocyanin, which is produced in response to a variety of stress conditions including pathogen and UV light stress, we aimed to characterise the extreme differences found between red-leaved 'Bon Rouge' Pyrus communis L. pear trees and their green sports, using a number of molecular tools. 'Bon Rouge' was derived from a rare, spontaneous bud mutation of the green pear cultivar William's 'Bon Chretien' ('Bartlett') and is characterised by red skinned fruit resulting from anthocyanin production. ‘Bon Rouge’ was observed to revert at a high frequency, producing green tissues in clonal stripes on stems and fruit. The production of both phenotypes on the same tree presents a system in which it is possible to study the control of colour development under the same set of environmental variables in an identical genetic background. Gene expression differences were measured by differential display and confirmed by quantitative RT-PCR. Seven of the differentially induced cDNA clones showed significant similarity to genes in database and include those associated with biotic and abiotic stress responses. Proteomic analysis shows substantial changes in expression of certain proteins that were further characterised by mass spectrometry (MS). Pigment analysis by HPLC, LC-MS and tandem MS confirmed the presence of cyanidin 3-galactoside (idaein) in the red phenotype by comparison with the commercial standard. Comparable analyses for the pigment in the green phenotype suggest that it is closely related to the pigment identified in the red phenotype with different substitutions on the basic ring structure. | |
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