33
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Transcriptional analysis of apple fruit proanthocyanidin biosynthesis

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Proanthocyanidins (PAs) are products of the flavonoid pathway, which also leads to the production of anthocyanins and flavonols. Many flavonoids have antioxidant properties and may have beneficial effects for human health. PAs are found in the seeds and fruits of many plants. In apple fruit ( Malus × domestica Borkh.), the flavonoid biosynthetic pathway is most active in the skin, with the flavan-3-ols, catechin, and epicatechin acting as the initiating units for the synthesis of PA polymers. This study examined the genes involved in the production of PAs in three apple cultivars: two heritage apple cultivars, Hetlina and Devonshire Quarrenden, and a commercial cultivar, Royal Gala. HPLC analysis shows that tree-ripe fruit from Hetlina and Devonshire Quarrenden had a higher phenolic content than Royal Gala. Epicatechin and catechin biosynthesis is under the control of the biosynthetic enzymes anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR1), respectively. Counter-intuitively, real-time quantitative PCR analysis showed that the expression levels of Royal Gala LAR1 and ANR were significantly higher than those of both Devonshire Quarrenden and Hetlina. This suggests that a compensatory feedback mechanism may be active, whereby low concentrations of PAs may induce higher expression of gene transcripts. Further investigation is required into the regulation of these key enzymes in apple.

          Abbreviations:

          ANOVA

          analysis of variance

          ANR

          anthocyanidin reductase

          DAD

          diode array detector

          DAFB

          days after full bloom

          DFR

          dihydroflavonol reductase

          LAR

          leucoanthocyanidin reductase

          LC-MS

          liquid chromatography/mass spectrometry

          PA

          proanthocyanidin

          qPCR

          real-time quantitative PCR

          Related collections

          Most cited references 32

          • Record: found
          • Abstract: not found
          • Article: not found

          Genetics and Biochemistry of Anthocyanin Biosynthesis.

            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Proanthocyanidins--a final frontier in flavonoid research?

            Proanthocyanidins are oligomeric and polymeric end products of the flavonoid biosynthetic pathway. They are present in the fruits, bark, leaves and seeds of many plants, where they provide protection against predation. At the same time they give flavor and astringency to beverages such as wine, fruit juices and teas, and are increasingly recognized as having beneficial effects on human health. The presence of proanthocyanidins is also a major quality factor for forage crops. The past 2 years have seen important breakthroughs in our understanding of the biosynthesis of the building blocks of proanthocyanidins, the flavan-3-ols (+)-catechin and (-)-epicatechin. However, virtually nothing is known about the ways in which these units are assembled into the corresponding oligomers in vivo. Molecular genetic approaches are leading to an understanding of the regulatory genes that control proanthocyanidin biosynthesis, and this information, together with increased knowledge of the enzymes specific for the pathway, will facilitate the genetic engineering of plants for introduction of value-added nutraceutical and forage quality traits.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              The grapevine transcription factor VvMYBPA1 regulates proanthocyanidin synthesis during fruit development.

              Proanthocyanidins (PAs; or condensed tannins) can protect plants against herbivores, contribute to the taste of many fruits, and act as dietary antioxidants beneficial for human health. We have previously shown that in grapevine (Vitis vinifera) PA synthesis involves both leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR). Here we report the characterization of a grapevine MYB transcription factor VvMYBPA1, which controls expression of PA pathway genes including both LAR and ANR. Expression of VvMYBPA1 in grape berries correlated with PA accumulation during early berry development and in seeds. In a transient assay, VvMYBPA1 activated the promoters of LAR and ANR, as well as the promoters of several of the general flavonoid pathway genes. VvMYBPA1 did not activate the promoter of VvUFGT, which encodes the anthocyanin-specific enzyme UDP-glucose:flavonoid-3-O-glucosyltransferase, suggesting VvMYBPA1 is specific to regulation of PA biosynthesis in grapes. The Arabidopsis (Arabidopsis thaliana) MYB transcription factor TRANSPARENT TESTA2 (TT2) regulates PA synthesis in the seed coat of Arabidopsis. By complementing the PA-deficient seed phenotype of the Arabidopsis tt2 mutant with VvMYBPA1, we confirmed the function of VvMYBPA1 as a transcriptional regulator of PA synthesis. In contrast to ectopic expression of TT2 in Arabidopsis, constitutive expression of VvMYBPA1 resulted in accumulation of PAs in cotyledons, vegetative meristems, leaf hairs, and roots in some of the transgenic seedlings. To our knowledge, this is the first report of a MYB factor that controls genes of the PA pathway in fruit, including both LAR and ANR, and this single MYB factor can induce ectopic PA accumulation in Arabidopsis.
                Bookmark

                Author and article information

                Journal
                J Exp Bot
                J. Exp. Bot
                jexbot
                exbotj
                Journal of Experimental Botany
                Oxford University Press (UK )
                0022-0957
                1460-2431
                September 2012
                1 August 2012
                1 August 2012
                : 63
                : 15
                : 5437-5450
                Affiliations
                1The New Zealand Institute for Plant & Food Research Limited (PFR), Private Bag 92 169 Auckland, New Zealand
                2PFR, Palmerston North Research Centre, Palmerston North 4442 New Zealand
                3School of Biological Sciences, University of Auckland, Private Bag 92019 Auckland, New Zealand
                Author notes
                *To whom correspondence should be addressed. E-mail: Rebecca.Kirk@ 123456plantandfood.co.nz
                Article
                10.1093/jxb/ers193
                3444262
                22859681
                © The Author [2012].

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/bync/3.0/uk/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Page count
                Pages: 14
                Categories
                Research Paper

                Comments

                Comment on this article