Isolation and Characterization of Soft Rot pathogen of Yam (Dioscorea spp) in Nigeria-A Review

Abstract: Yam (Dioscorea spp) is a tuber crop belonging to the family Dioscoreaceae. The species of economic importance include Dioscorea rotundata, Dioscorea alata, Dioscorea cayenensis, Dioscorea dumetorum, Dioscorea bulbifera and Dioscorea esculentus. In West Africa, Dioscorea rotundata is also refered to as white yam or white guinea yam. It is the most widely cultivated. It is the most important food and income source for millions of producers, processors and consumers in West Africa. A pathogen or infectious agent is a biological agent that causes disease or illness to its host and it can infect unicellular organisms from all of the biological kingdoms. In the oldest and broadest sense, it is anything that can produce disease, a term which came into use in the 1880s ("Pathogen". Dictionary.com Unabridged. Random House ; Casadevall, Arturo; Pirofski, Liise-anne 2014). It is used to describe an infectious agent like the following: virus, bacterium, prion, fungus, viroid, or parasite that causes disease in its host. The host may be a human, an animal, a plant, a fungus, or even another micro-organism (Alberts B et al., 2002; MetaPathogen, 2015). There are different types of pathogens which include the following: Bacterial, Viral, Fungal, Prionic Protozoa, Viroids and Human Parasite. Isolation It is defined as the complete separation from others of a person or plant suffering from contagious or infectious disease; quarantine. It is very damaging, and there is no way to ameliorate it and isolation of pathogen is the process whereby pathogens of yam are treated. This is the process where rotted yam tubers were rinsed in distilled water, surface sterilized with 70% ethanol and cut open with a sterilized knife and it is now treated.