Submitted to: Fungal Genetics Conference/Asilomar
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2003
Publication Date: 4/15/2003
Citation: GLENN, A.E., BACON, C.W. 2003. IDENTIFICATION OF FDB1, FDB2, AND OTHER FUSARIUM VERTICILLIOIDES GENES EXPRESSED IN RESPONSE TO BOA, A MAIZE ANTIMICROBIAL COMPOUND. FUNGAL GENETICS CONFERENCE/ASILOMAR. v.50. p.120. Interpretive Summary: Abstract - no interpretive summary required. 22nd Fungal Genetics Conference, Asilomar Conference Center, Pacific Grove, CA, March 18-23, 2003.
Technical Abstract: Maize produces antimicrobial compounds (DIMBOA, DIBOA, MBOA, and BOA) implicated in disease resistance and insect feeding deterrence. Fusarium verticillioides, the most common fungal pathogen associated with maize, has the physiological capacity to biotransform these compounds into non-toxic metabolites. While data suggest such biotransformation is not a major virulence factor, the metabolic capacity may enhance the ecological fitness of F. verticillioides in a cornfield environment. Genetic analyses showed at least two loci, FDB1 and FDB2, are necessary for biotransformation. The biotransformation pathway for BOA is suggested to involve hydrolysis (Fdb1p) to produce 2-aminophenol, which is subsequently modified by addition of a malonyl group (Fdb2p) to produce N-(2-hydroxyphenyl) malonamic acid. If either gene is mutated, detoxification does not occur and the fungus cannot grow on BOA-amended medium. In an effort to molecularly characterize FDB1 and FDB2 as well as other genes involved in biotransformation, suppression subtractive hybridization (SSH) was used to target genes up-regulated in response to BOA. Among the clones identified, those with similarities to amidase and arylamine N-acetyltransferase were of particular interest, since these enzymes catalyze chemical modifications similar to those postulated for Fdb1p and Fdb2p. Genomic cosmid clones were identified for each using the respective cDNAs as probes. The putative amidase cosmid genetically complemented an fdb1 mutation, while the putative N-malonyltransferase cosmid complimented an fdb2 mutation. Thus, the proposed chemical modifications and the putative proteins involved are mutually supported. Also, these results demonstrate the utility of SSH for cloning genes previously identified by forward genetics.