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Accueil du site → Doctorat → Royaume-Uni → 2007 → An investigation of phytotoxicity and phylogeny of Thapsia garganica (Libya)

Salford University (2007)

An investigation of phytotoxicity and phylogeny of Thapsia garganica (Libya)

Bataw, M

Titre : An investigation of phytotoxicity and phylogeny of Thapsia garganica (Libya)

Auteur : Bataw, M

Université de soutenance : Salford University

Grade : Doctor of Philosophy (PhD) 2007

Résumé
Thapsia garganica is an economically important plant in Libya as it has major influences on domestic livestock production and on the locations that can be used for livestock productivity due to its toxicity to domestic animals. The aims of this thesis were to investigate aspects of this plant species which may improve our general understanding of it and to provide tools which may be useful in Libyan agriculture. To be able to conduct studies on Thapsia, it is necessary to have growing plant material in the laboratory. Different growth conditions were tried which ultimately only succeeded in enabling development of weak seedlings of 10-20cm in height in contrast to the 1m high plants found in the wild. To try to identify the factors which promote growth of Thapsia in the wild, a literature/data survey was carried out locally in Libya to determine factors (eg. temperature, rainfall, soil type) which might affect plant growth. It was found that Thapsia grows in a wide range of conditions in the wild in Libya. There were no specific factors that could explain its failure to grow in the laboratory, greenhouse or plant culture cabinet despite growing like a weed in Libya. A bioassay system was developed for the detection of plant toxins from Thapsia garganica using bacterial and yeast culture systems. Although, thapsigargin and other toxins have been reported in Thapsia garganica (Smitt, et., al. 1995) and have been used extensively as specific inhibitors of cell metabolism in experimental systems, many of these assay systems used are not suitable for local use in Libya. A bacterial bioassay system did not respond to the toxic effects of plants but a yeast liquid culture bioassay did prove to be effective against thapsigargin. Furthermore, extracts of plants collected from Libya could also be demonstrated to have a toxic effect on the yeast culture system. Thus demonstrating its potential use for detection of toxic effects. Few genes to date have been isolated from Thapsia garganica. One of the aims of this thesis was to isolate DNA from Thapsia garganica and to gain DNA sequence information which could be used to investigate the taxonomy of Thapsia garganica. The trnL gene intron was amplified by PCR and the DNA sequence obtained. This sequence was used to investigate Thapsia phylogeny and the results supported the classical taxonomy of Thapsia in the Umbellifereae. The DNA sequence could be used in the future as a basis for a diagnostic test for Thapsia contamination of livestock feed.

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