No abstract

Niger plant (Guizotia abyssinica), exhibits phenotypic plasticity in different environments. There is need to assess its genetic diversity since guizotia species has a high number of species which may be confused amongst themselves. To achieve this, inter simple sequence repeat (ISSR) markers were used to estimate genetic diversity among 12 wild populations of Niger plant from Moiben sub-county. Total genomic DNA was extracted as per the cetyltrimethylammonium bromide (Ctab) method and subjected to ISSR analysis using 20 primers. None of the primers produced unique banding patterns. ISSR data were used to calculate a squared-euclidean distance matrix. All the twenty primers (100%) gave polymorphic bands thus they were all considered for further analysis. The allele frequency of all the primers was below 0.95 indicating that they were all polymorphic in character. Gene diversity was high ranging from 0.3550 to 0.7337 with a mean value of 0.6302. The ISSR based upgma clustering produced four clusters. Niger plant within Moiben sub-county was found to be genetically diverse though heterozygosity was not noticed. The study recommends further analysis of Niger plant so as to form a basis for further development of the plant.

Plants produce chemical compounds as a result of secondary metabolism. The chemical compounds cannot be directly linked with plant growth and development but can influence several processes in the ecosystem. These compounds are known as secondary metabolites or all elochemicals. Important secondary metabolites include alkaloids, terpenes, phenolics and vitamins. Most secondary metabolites are toxic and therefore play defensive roles against biotic factors like protection from attack of pathogens, herbivores pests and weeds [10]. Due to this, plants can regulate the microbial community in their immediate vicinity, endure herbivores, encourage symbiotic improvement, change the physical and chemical properties of the surrounding environment and inhibit the growth of plant competitive species [13]. Depending on the specific allelochemical considered, the target plant and the concentration in the soil, allelochemicals can act either positively or negatively [6]. In agroecosystems, allelopathy can affect weed management, plant reproduction, species consortia, the mulching effect on crops and the succession and rotation of cultivated species [4]. Additionally, allelochemicals have the potential to be used for herbicide synthesis, enabling the discovery of new mechanisms of action. Wise exploitation of allelopathy in cropping systems may be an effective, economical and natural method of weed management, and a substitute for heavy use of herbicides. Allelochemicals have a great potential as bio-herbicides since they have a shorter half-life and thus can be rapidly biodegraded. Their mode of action is different from synthetic herbicides owing to comparatively fewer halogen substituents and no unnatural ring structures [14]. Allelochemicals, also known as phytochemicals, are environmentally friendly because they have low or no toxicity to animals and beneficial insects, possess an array of activity with varying and diverse sites of action and have a comparatively high degradation rate [5]. Plants in the family Asteracea have been noted to be highly allelopathic [13]. It has been observed that, Niger plant, a plant in this family, is a good precursor for cereals, pulses and oil seeds, because crops following Niger plant have less weed infestation [2]. This experiment was therefore carried out to determine the presence and amount of secondary metabolites in Niger plant within Moiben sub-county.