PJB-2020-45
Melatonin Interposed Lead Absorption: The Anatomical Changes in Amaranthus cruentus L.
David Oyinade Aderoju
Abstract
Amaranthus cruentus is an important leafy vegetable that is majorly consumed and cultivated largely even in sewage sludge environment with high level of heavy metals. Melatonin is a hormone which helps to stimulate vegetative growth of plant under stress. The study aimed at the effect of melatonin on lead absorption of A. cruentus in relation to their anatomical changes. Sterilized seeds of A. cruentus were primed in varying concentration of Melatonin (0 and 400µM to represent M0 and M400) for 24hours. Primed seeds were planted into 3kg of sterilized soil. Plants were exposed to Lead concentration (0, 10 and 20Mm to represent P0, P10 and P20) once a week till fruiting stage. Eleven (11) weeks after planting, Lead concentration at the leaves and roots were analyzed using Atomic Absorption Spectrometry (AAS). Leaves were sectioned transversely, stained and viewed under microscope at 200x. Melatonin significantly (P<0.05) reduced Lead concentration at the root (33%) and leaves (67%) in treatment AcM400P20 and AcM400P10 respectively. Root vascular bundles of treatment AcM400P20 were 70% wider than its control (AcM0P20). A significant (P<0.05) thickened of the root epidermis were observed in plant treatment AcM400P20 however, increased number of staggered vascular bundles were observed at the leaves of all plants treated with melatonin. Melatonin sequesters, localized and immobilized Lead at the root of A. cruentus which were reflected in the thickened of the root epidermis hence, restricted translocation of Lead to the leaves for healthy survival and protection of photosynthesis apparatus. Melatonin distorted the concentric arrangement of the leaves vascular bundles. Size of root epidermis and cuticle of A. cruentus were inversely related and presence of trichomes at adaxail and abaxial helped to maintained leaves turgidity which were responses of A. cruentus to Lead stress.
To Cite this article:
Download
