Effects of laeA deletion on Aspergillus flavus conidial development and hydrophobicity may contribute to loss of aflatoxin production

• Published in: Fungal biology Vol. 116; no. 2; pp. 298 - 307
• Main Authors: Chang, Perng-Kuang, Scharfenstein, Leslie L., Ehrlich, Kenneth C., Wei, Qijian, Bhatnagar, Deepak, Ingber, Bruce F.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.02.2012
• Subjects: Aflatoxin; aflatoxins; Aflatoxins - metabolism; aflR; Aspergillus flavus; Aspergillus flavus - chemistry; Aspergillus flavus - genetics; Aspergillus flavus - growth & development; Aspergillus nidulans; Aspergillus nidulellus; Carbohydrate Metabolism; Conidiation; conidiophores; Culture Media - chemistry; fungi; Gene Deletion; Gene Expression Regulation, Fungal; genes; Hydrophobic and Hydrophilic Interactions; Hydrophobicity; Methyltransferases - genetics; Methyltransferases - metabolism; mutants; Norsolorinic acid anthrone; secondary metabolites; Solanum tuberosum; Spores, Fungal - chemistry; Spores, Fungal - genetics; Spores, Fungal - growth & development; sugars; Norsolorinic acid anthrone; Hydrophobicity; aflR; Conidiation; Aflatoxin
• ISSN: 1878-6146; 1878-6162
• DOI: 10.1016/j.funbio.2011.12.003

LaeA of Aspergillus nidulans is a putative methyltransferase and a component of the velvet complex; it is thought to mainly affect expression of genes required for the production of secondary metabolites. We found that although Aspergillus flavus CA14 laeA deletion mutants showed no aflatoxin production, expression of some of the early genes involved in aflatoxin formation, but not the later genes, could still be detected. The mutants grown in minimal medium supplemented with simple sugars and on some complex media exhibited altered conidial development. On potato dextrose agar (PDA) medium the deletion mutants showed reduced conidial chain elongation, increased production of conidiophores, and decreased colony hydrophobicity when compared to the parental strain. The loss of hydrophobicity and the other developmental changes in the laeA deletion mutants could affect the ability of the fungus to produce aflatoxins. ► laeA deletion mutants in A. flavus CA14 do not produce aflatoxins. ► The mutants produce reduced conidia on certain media. ► The mycelia in mutants is less hydrophobic and conidial chains are shorter. ► Expression of early aflatoxin biosynthesis genes in mutants is reduced. ► Expression of the ‘late’ genes, ver1 and omtA was not found.