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Accueil du site → Doctorat → Royaume-Uni → 2003 → Systematics and population variation of the Genus Senna L. (Leguminosae) in Saudi Arabia

University of London - Birkbeck ( (2003)

Systematics and population variation of the Genus Senna L. (Leguminosae) in Saudi Arabia

Al-Fredan, Mohammed Abdulwahab

Titre : Systematics and population variation of the Genus Senna L. (Leguminosae) in Saudi Arabia

Auteur : Al-Fredan, Mohammed Abdulwahab.

Université de soutenance : University of London - Birkbeck (

Grade : Doctor of Philosophy (Ph.D.) : 2003

A systematic study of the taxa of Senna native to Saudi Arabia was carried out utilising morphological, anatomical, cytological and chemical data obtained from plants raised in controlled conditions in a glasshouse. The biological activity of some compounds was assayed. In addition herbarium specimens from Saudi Arabia and surrounding regions were studied of the taxa native to Saudi Arabia and other closely related taxa. Leaves with dorsiventral anatomy were observed in S. italica, S. alexandrina and holosericea, whereas isobilateral leaves occurred in S. occidentalis and S. tora. The distribution of trichomes was usually isobilateral, only adaxial in S. tora, and trichomes were absent in S. occidentalis. All populations were diploid but with variation between populations in chromosome number (2n = 20, 22, 24, 26, 28). Variation in karyotype was all recorded but impossible to analyse effectively because of the small size of chromosomes (mean size 1.3-2.6 mm). A study of amino acids and flavonoids of the seeds, pods and leaves of the five species from the taxa in Saudi Arabia was carried out using High Voltage Electrophoresis (HVE), Gas Chromatography-Mass Spectrometry (GC-MS), Liquid Chromatography-Mass Spectrometry (LC-MS) and High Performance Liquid Chromatography (HPLC). Thirty eight different and many unknown compounds were isolated from Senna species. The major essential oil components proved to be : alanine, glycine, proline, aspartic acid, glutamic acid, apigenin, vicenin-2 and chrysoeriol. A study of the biological activity of the genus Senna was carried out with two species from insects, Callosobruchus maculatus and Tribolium confusum. Compounds from S. tora and S. holosericea reduced the emergence of adult insects. Overall results demonstrated that some taxa previously thought to be distinct, might only be variants of a single geographically variable species. There are three distinct species groups, S. italica, S. holosericea and S. alexandrina, and S. obtusifolia and S. tora, and S. occidentalis and S. sophera.

Présentation : EThOS (UK)

Accès au document : Proquest Dissertations & Theses

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