title: Identification of Aspergillus flavus isolates as potential biocontrol agents of aflatoxin contamination in crops.
abstract: Aspergillus flavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops.
authors.affiliation: Departamento de Biotecnologia, Genética e Biologia Celular, Laboratório de Genética de Microrganismos, Universidade Estadual de Maringá, Avenida Colombo 5790, Maringá, CEP 87020-900, PR, Brasil.
authors.forename: L J
authors.initials: LJ
authors.lastname: Rosada
authors.forename: J R
authors.initials: JR
authors.lastname: Sant'anna
authors.forename: C C S
authors.initials: CC
authors.lastname: Franco
authors.forename: G N M
authors.initials: GN
authors.lastname: Esquissato
authors.forename: P A S R
authors.initials: PA
authors.lastname: Santos
authors.forename: J P R S
authors.initials: JP
authors.lastname: Yajima
authors.forename: F D
authors.initials: FD
authors.lastname: Ferreira
authors.forename: M
authors.initials: M
authors.lastname: Machinski
authors.forename: B
authors.initials: B
authors.lastname: Corrêa
authors.forename: M A A
authors.initials: MA
authors.lastname: Castro-Prado
mesh_terms: D000348:Aflatoxins / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D010367:Arachis / Q000382:microbiology; D001231:Aspergillus flavus / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005506:Food Contamination / Q000517:prevention & control*; D005516:Food Microbiology; D014644:Genetic Variation; D011995:Recombination, Genetic; D003313:Zea mays / Q000382:microbiology
chemical_list: D000348:Aflatoxins