Involvement of an extracellular fungus laccase in the flavonoid metabolism in Citrus fruits inoculated with Alternaria alternata
Copyright © 2015 Elsevier Masson SAS. All rights reserved.
| Veröffentlicht in: | Plant physiology and biochemistry : PPB. - 1991. - 89(2015) vom: 01. Apr., Seite 11-7 |
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| Weitere Verfasser: | , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2015
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| Zugriff auf das übergeordnete Werk: | Plant physiology and biochemistry : PPB |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Citrus limon Citrus paradisi Flavanones Flavones Laccase ‘Fortune’ mandarin Coumarins Flavonoids mehr... |
| Zusammenfassung: | Copyright © 2015 Elsevier Masson SAS. All rights reserved. Fungi of the genus Alternaria are responsible for substantial pre-harvest losses in Citrus. In this study a degradative metabolism of flavonoids (flavanones, flavones and polymethoxyflavones) was observed when 'Fortune' mandarin, Citrus limon and Citrus paradisi, fruits were inoculated with Alternaria alternata, a pre-harvest pathogenic fungus. Associated to this flavonic metabolism the de novo synthesis of the phytoalexin scoparone was detected. This metabolism of flavonoids is caused by an extracellular fungus laccase. The kinetic characterisation of this enzyme revealed that the activity was induced by Citrus flavonoids and was dependent on flavonoid concentrations. The enzyme exhibited a Km of 1.9 mM using ABTS as substrate with an optimum pH of 3.5 in citrate buffer 100 mM. The enzyme is active between 15 and 45 °C, the optimum temperature being around 35 °C, although 50% of the initial activity is lost after 45 min at 35 °C. The A. alternata laccase was inhibited by 0.5 mM l-cysteine and by caffeic acid. Study of the substrate specificity of this enzyme revealed that Citrus flavonoids are substrates of A. alternata laccase. These results suggest that the laccase enzyme could be involved in the pathogenesis of A. alternata in Citrus |
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| Beschreibung: | Date Completed 30.11.2015 Date Revised 16.03.2022 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1873-2690 |
| DOI: | 10.1016/j.plaphy.2015.02.006 |