Identification of Micro RNA like Elements from Transcriptome data of Aspergillus Flavus

Abstract

Aspergillus flavus is a sapropyhtic and opportunistic pathogenic fungus with a cosmopolitan distribution. It is best known for its colonisation of cereal grains, legumes, and tree nuts. Postharvest rot typically develops during harvest, storage, and/or transit.[1] It grows by producing thread like branching filaments known as hyphae. A network of hyphae known as mycelium secretes enzymes that break down complex food sources. The resulting small molecules are absorbed by mycelium to fuel additional fungal growth. A. flavus is unique in that it is a thermotolerant disease, so can survive at temperatures that other diseases cannot. A. flavus can contribute to the storage rots, especially when the plant material is stored at high moisture levels. A. flavus grows and thrives in hot and humid climates.[2]A. flavus has a minimum growth temperature of 12°C (54°F) and a maximum growth temperature of 48°C (118°F). Though the maximum growth temperature is around 48°C (118°F), the optimum growth temperature is 37°C (98.6°F). A. flavus had rapid growth at 30–55°C, slow growth at 12–15°C, and almost ceases growth at 5–8°C.[3] Aspergillus flavus is ubiquitous in nature, capable of infecting a broad range of host and produces highly toxic metabolites called aflatoxin . Among various types of aflatoxins viz. AFB1, AFB2, AFG1 and AFG2; AFB1 hasbeen found to be most common contaminant of major crop such as corn, peanuts, cotton and other pre/post-harvested crops. Aflatoxins are genotoxic carcinogen in which AFB1 is the most toxic compound classified in 1994 by the International Agency for Research on Cancer (IARC).Regular consumption of low level of aflatoxin through contaminated food products causes aflatoxicosis which is characterized by jaundice, rapidly developing ascites, hypertension, vomiting, abdominal pain, pulmonary edema, fatty infiltration and necrosis of the liver.[11] It is important because it produces aflatoxin as a secondary metabolite in the seeds of a number of crops both before and after harvest. Aflatoxins are toxic compounds chemically related to bisfuranocoumarin that are produced by A. flavus and A. parasiticus strains. These two aflatoxigenic species have been frequently studied due to their impact on agricultural 8 commodities and their devastating effects on livestock. The name “aflatoxin” comes from the genus Aspergillus, which is where the letter “a” in aflatoxin is derived and “fla” from the species name flavus. In agricultural grains the fungi A. flavus and A. parasiticus are capable of producing four major aflatoxins(AfB1, AfB2, AfG1, and AfG2). A. flavus typically produces only the B toxins.