ISHS Acta Horticulturae 663: XI Eucarpia Symposium on Fruit Breeding and Genetics
DIFFERENTIAL GENE EXPRESSION PATTERNS FOR RED AND GREEN PHENOTYPES OF 'BON ROUGE' PEAR TREES, PYRUS COMMUNIS L. |
| Authors: | M.G. du Preez, I.F. Labuschagné, D.J.G. Rees |
| Keywords: | differential display, stress response, PCR |
| Abstract:
Red blush on a green or yellow fruit skin is a desirable trait in many export cultivars under commercial production in the Western Cape region of South Africa. To investigate the underlying mechanism controlling the production of red pigment, anthocyanin, which is produced in response to a variety of stress conditions including pathogen and UV light stress, we compared gene expression between red leaved ‘Bon Rouge’ (Pyrus communis L.) pear trees and their green (reverted) sports. Differential display reverse transcription-polymerase chain reaction (DD RT-PCR) was used to detect differential gene expression between the two phenotypic variants and differential expression was confirmed by quantitative RT-PCR. Twenty-nine cDNA bands representing genes that are differentially regulated between red and green phenotypes, were cloned, sequenced and subjected to similarity searches on available database using the BLAST tool. Seven cDNA clones showed significant similarity to genes in databases and include those associated with light stress and pathogenesis responses, and protein synthesis. Six clones corresponding to Early Light Inducible Protein (ELIP), a defensin, a sulfoquinovosyl synthase (SQD2), proline synthetase associated protein (PSAP), an unknown expressed gene and glutaminyl tRNA synthetase (QRS) respectively, were further investigated. Quantitative RT-PCR analysis confirmed up-regulation of ELIP, QRS, defensin and the uncharacterised gene expression in the red form, and PSAP and SQD2 gene expression in the green form. Despite there being only a single gene difference between red and green genotypes, this extensive pattern of altered gene expression suggests this system presents an opportunity to identify a controlling element/gene for stress responses in plants. The enhanced production of anthocyanin in the red phenotype appears to arise as a consequence of a combination of biotic and abiotic stress responses, not as the direct result of mutations in anthocyanin biosynthetic pathway genes. | |
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