title: An isolate of Aspergillus flavus used to reduce aflatoxin contamination in cottonseed has a defective polyketide synthase gene.
abstract: Contamination of certain foods and feeds with the highly toxic and carcinogenic family of Aspergillus mycotoxins, the aflatoxins, can place a severe economic burden on farmers. As one strategy to reduce aflatoxin contamination, the non-aflatoxin-producing A. flavus isolate AF36 is currently being applied to agricultural fields to competitively exclude aflatoxin-producing Aspergillus species. We now show that the polyketide synthase gene (pksA) required for aflatoxin biosynthesis in AF36, and in other members of the same vegetative compatibility group, possesses a nucleotide polymorphism near the beginning of the coding sequence. This nucleotide change introduces a premature stop codon into the coding sequence, thereby preventing enzyme production and aflatoxin accumulation.
authors.affiliation: Southern Regional Research Center/ARS/USDA, PO Box 19687, New Orleans, LA 70179, USA. ehrlich@srrc.ars.usda.gov.
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Ehrlich
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Cotty
mesh_terms: D000348:Aflatoxins / Q000096:biosynthesis / Q000235:genetics; D000595:Amino Acid Sequence; D001231:Aspergillus flavus / Q000201:enzymology* / Q000235:genetics*; D001483:Base Sequence; D018389:Codon, Nonsense; D003369:Cottonseed Oil; D004271:DNA, Fungal / Q000737:chemistry; D005506:Food Contamination; D015870:Gene Expression; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D048630:Polyketide Synthases / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA
chemical_list: D000348:Aflatoxins; D018389:Codon, Nonsense; D003369:Cottonseed Oil; D004271:DNA, Fungal; D012331:RNA, Fungal; D012333:RNA, Messenger; D048630:Polyketide Synthases