EC Accepts, published online ahead of print on 1 May 2009

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Eukaryotic Cell doi:10.1128/EC.00088-09
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Distinct roles for VeA and LaeA in development and pathogenesis of Aspergillus flavus

Saori Amaike and Nancy P. Keller^*

Department of Plant Pathology, Department of Medical Microbiology and Immunology, and Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Dr., Madison, WI 53706-1598

^* To whom correspondence should be addressed. Email: npkeller{at}wisc.edu.

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 A. 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 2+ each) revealed critical roles for VeA and LaeA in A. flavus development and seed colonization. In contrast to wildtype, both null mutants were unable to metabolize host cell lipid reserves and were inhibited by oleic acid in growth assays. Copy number of LaeA but not VeA appeared critical for a density dependent sclerotial-to-conidial shift as the MClaeA strain produced relatively constant sclerotial numbers with increasing population size rather than the decrease in sclerotia seen in both wildtype 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.