Distinct roles for VeA and LaeA in development and pathogenesis of Aspergillus flavus.
Aspergillus flavus, a mycotoxigenic filamentous fungus, colonizes several important agricultural crops, such as maize and peanuts. Two proteins, VeA and LaeA, known to form a nuclear complex in Aspergillus nidulans have been found to positively regulate developmental processes in several Aspergillus species. Here, an examination of near-isogenic A. flavus mutants differing in copy number of veA and laeA alleles (0, 1, or at least 2 each) revealed critical roles for VeA and LaeA in A. flavus development and seed colonization. In contrast to the wild type, both null mutants were unable to metabolize host cell lipid reserves and were inhibited by oleic acid in growth assays. The copy number of LaeA but not VeA appeared critical for a density-dependent sclerotial-to-conidial shift, since the multicopy laeA (MClaeA) strain produced relatively constant sclerotial numbers with increasing population size rather than showing the decrease in sclerotia seen in both the wild-type and MCveA strains. The MCveA-laeA strain yielded an intermediate phenotype. This study revealed unique roles of VeA and LaeA in seed pathogenesis and fungal biology, distinct from their cooperative regulatory functions in aflatoxin and sclerotial development.
Amaike
Saori
S
Department of Plant Patholog, University of Wisconsin-Madison, Wisconsin 53706-1598, USA.
Keller
Nancy P
NP
D001231:Aspergillus flavus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D048690:Fruiting Bodies, Fungal; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D050356:Lipid Metabolism / Q000235:genetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation / Q000235:genetics; D019301:Oleic Acid / Q000378:metabolism; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics; D012639:Seeds / Q000378:metabolism / Q000382:microbiology; D013172:Spores, Fungal / Q000235:genetics / Q000254:growth & development
D005656:Fungal Proteins; D019301:Oleic Acid