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Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze
Dissertation (MSc)--University of Pretoria, 2008.
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University of Pretoria
2013
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| _version_ | 1867613521996414976 |
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| access_status_str | Open Access |
| author2 | Labuschagne, Nico |
| author_browse | Labuschagne, Nico |
| author_facet | Labuschagne, Nico |
| collection | Thesis |
| dc_rights_str_mv | © 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc)--University of Pretoria, 2008. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/26854 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:37:28.861Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/26854 Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze Labuschagne, Nico Apostolides, Zeno upetd@up.ac.za Wilmot, Michelle Vegetable crops by catechins Phytopathogenic fungi UCTD Dissertation (MSc)--University of Pretoria, 2008. The aim of our study was to determine whether Polyphenon G (PPG, a concentrated Camellia sinensis extract) and the individual compounds in PPG had activity against phytopathogenic fungi in vitro and in vivo. The present study reports on the sensitivity of twenty different phytopathogenic fungal species to extracts from black-, green- and rooibos tea extracts, concentrated green tea extract (Polyphenon G), caffeine, theanine, epigallocatechin gallate (EGCg), epicatechin gallate (ECg), epigallocatechin (EGC), and epicatechin (EC), and Polyphenon G combined with caffeine. The inhibition of fungal growth by the compounds was as follows (in decreasing order): caffeine > EGCg ECg > EGC EC > Polyphenon G > green tea extracts black tea extracts > rooibos tea extracts theanine. In some cases the Polyphenon G and caffeine combination reduced the IC50 values for both the compounds, indicating a synergistic effect. Phytophthora nicotianae and P. capsici were most sensitive to all the compounds, while Rhizopus stolonifer and Penicillium expansum were least sensitive. PPG and caffeine was subsequently tested individually and in combination in a greenhouse trial against seven pathogens on four crops. The combinations of Polyphenon G and caffeine gave the best overall results and effectively controlled Fusarium solani on cucumber, P. capsici and Sclerotium rolfsii on tomato, Sclerotinia sclerotiorum and Pythium F-group on lettuce. PPG individually significantly inhibited the growth of Sphaerotheca fuliginea of zucchini squash plants. In efforts to determine the mode of action of PPG, caffeine and the combination thereof, methods used in our study included determining total phenolic content by means of the Folin-Ciocalteu reagent, thin layer chromatography (TLC) bioautography to identify possible anti-microbial compounds and high performance liquid chromatography (HPLC) for identifying induced compounds based on standards included in the analysis. Results showed that ferulic, salicylic and caffeic acids increased in uninfected lettuce plants treated with a combination of PPG and caffeine. These results indicate that either the phenolic compounds in the treatments were accumulated in the roots or that the treatments induced de novo synthesis in the plants to increase the production of phenolic compounds or that the treatments caused induction of resistance in the plant. The results of the current study demonstrate the potential for tea (C. sinensis) extracts to be developed as effective crop protection agents against a range of plant diseases on a variety of crops. Microbiology and Plant Pathology unrestricted 2013-09-07T08:21:06Z 2008-08-05 2013-09-07T08:21:06Z 2007-04-20 2008-08-05 2008-07-30 Dissertation Wilmot, M 2006, Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/26854 > E577/ag http://hdl.handle.net/2263/26854 http://upetd.up.ac.za/thesis/available/etd-07302008-144409/ © 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Vegetable crops by catechins Phytopathogenic fungi UCTD Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze |
| title | Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze |
| title_full | Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze |
| title_fullStr | Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze |
| title_full_unstemmed | Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze |
| title_short | Inhibition of phytopathogenic fungi on selected vegetable crops by catechins, caffeine, theanine and extracts of Camellia sinensis (L.) O. Kuntze |
| title_sort | inhibition of phytopathogenic fungi on selected vegetable crops by catechins caffeine theanine and extracts of camellia sinensis l o kuntze |
| topic | Vegetable crops by catechins Phytopathogenic fungi UCTD |
| url | http://hdl.handle.net/2263/26854 http://upetd.up.ac.za/thesis/available/etd-07302008-144409/ |