The sparse development of mechanical tissues in moringa Oleifera linn. Is a trade-off between strength and storage of Secondary metabolites

Abstract

Moringa oleifera Lam. leaves, stem and roots are widely used in Nigeria for medicinal and culinary purposes. Adulteration and substitution are both potential hindrances to safe and effective utilization of this plant. Leaf, stem and root samples of M. oleifera were collected, oven-dried, ground into powder form and studied anatomically in search of micromorphological characters to identify the plant from its fragments. Moistened head of the needle was used to transfer powder specimens into a glass slide containing 1-2 drops of water and glycerol/ethanol TS; covered with cover slip and warmed gently to remove air bubbles. The results obtained revealed scanty sclerenchyma tissue rich in globular materials. Epidermal cells, fibres, rays and vessel elements all contained copious ergastic substances. Tyloses were abundant in the vessel elements of both root and stem while large oxalate crystals bound in calcium were numerous in the leaf epidermis. The extensive development of storage parenchyma cells in places where fibres are expected to provide wood strength and support is suggestive of a trade-off mechanism of strength for storage advantage. There is a hint that M.oleifera has a network of specially adapted storage tissues making it a candidate plant for commercial production of secondary metabolites in Nigeria. Detection of identifiable tissues in the powder form of Moringa by using anatomical method could provide a rapid and basic method of detecting adulteration and substitution in the commercial products of this widely used plant for quality assurance and forensic purposes.

Key words: Moringa oleifera, Anatomical characters, Scanty sclerenchyma tissue, Secondary metabolite, Adulteration and Substitution.