Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2004
Publication Date: 5/30/2004
Citation: Yu, J., Kim, H., Whitelaw, C.A., Nierman, W.C., Bhatnagar, D., Cleveland, T.E. 2004. Gene profiling by EST and microarray in Aspergillus flavus for controlling aflatoxin contamination in crops [abstract]. 7th European Conference on Fungal Genetics and 1st Aspergillus Workshop, April 17-21, 2004, Copenhagen, Denmark.
Technical Abstract: Aflatoxins are toxic and the most carcinogenic compounds produced by Aspergillus flavus and A. parasiticus that contaminate food and feed commodities when these fungi infect crops such as cotton, corn, peanuts, and tree nuts. Molecular studies on the genetics of aflatoxin biosynthesis established a well organized aflatoxin pathway gene cluster consisting of 25 genes within 70 kb DNA region. Over 16 enzymatic reactions are demonstrated to be directly involved in aflatoxin biosynthesis. Carbon and nitrogen metabolisms have been also shown to be related to aflatoxin formation. In order to better understand the molecular mechanism and regulation of aflatoxin biosynthesis, gene profiling through A. flavus Expressed Sequenced Tag (EST) and microarray technologies have been carried out. A total of 7,214 unique EST sequences have been identified from a normalized A. flavus NRRL 3357 cDNA library. Among the genes identified, many are rare copy genes potentially involved in secondary metabolism and gene regulation. In addition to the known aflatoxin biosynthetic genes identified, many of the genes that may be involved directly or indirectly in aflatoxin formation have been also identified among the sequenced clones. Microarray containing all of these unique genes has been used in gene profiling under aflatoxin supportive and non-supportive medium conditions. Gene knockout experiments are underway to characterize their functionality. Some of these genes could be targeted for genetic engineering of antifungal crops for eliminating aflatoxin contamination of food and feed commodity.