Document Detail

Deletion of the Delta12-oleic acid desaturase gene of a nonaflatoxigenic Aspergillus parasiticus field isolate affects conidiation and sclerotial development.
MedLine Citation:
PMID:  15546408     Owner:  NLM     Status:  MEDLINE    
AIMS: To investigate how linoleic acid affects conidial production and sclerotial development in a strictly mitotic Aspergillus parasiticus field isolate as related to improving biocompetitivity of atoxigenic Aspergillus species. METHODS AND RESULTS: We disrupted A. parasiticusDelta12-oleic acid desaturase gene (odeA) responsible for the conversion of oleic acid to linoleic acid. We examined conidiation and sclerotial development of SRRC 2043 and three isogenic mutant strains deleted for the odeA gene (DeltaodeA), either with or without supplementing linoleic acid, on one complex potato dextrose agar (PDA) medium and on two defined media: nitrate-containing Czapek agar (CZ) and Cove's ammonium medium (CVN). The DeltaodeA mutants produced less conidia than the parental strain on all media. Linoleic acid supplementation (as sodium linoleate at 0.3 and 1.2 mg ml(-1)) restored the DeltaodeA conidial production comparable to or exceeding the unsupplemented parental level, and the effect was medium dependent, with the highest increase on CVN and the least on PDA. SRRC 2043 and the DeltaodeA mutants were unable to produce sclerotia on CVN. On unsupplemented PDA and CZ, DeltaodeA sclerotial mass was comparable to that of SRRC 2043, but sclerotial number increased significantly to two- to threefold. Supplementing linoleic acid to media, in general, tended to decrease wild type and DeltaodeA sclerotial mass and sclerotial number. CONCLUSIONS: Linoleic acid stimulates conidial production but has an inhibitory effect on sclerotial development. The relationship between the two processes in A. parasiticus is complex and affected by multiple factors, such as fatty acid composition and nitrogen source. SIGNIFICANCE AND IMPACT OF STUDY: Conditions that promote sclerotial development differ from those required to promote maximum conidial production. Manipulation of content and availability of linoleic acid at different fungal growth phases might optimize conidial and sclerotial production hence increasing the efficacy of biocompetitive Aspergillus species.
P-K Chang; R A Wilson; N P Keller; T E Cleveland
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied microbiology     Volume:  97     ISSN:  1364-5072     ISO Abbreviation:  J. Appl. Microbiol.     Publication Date:  2004  
Date Detail:
Created Date:  2004-11-19     Completed Date:  2005-04-11     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  9706280     Medline TA:  J Appl Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1178-84     Citation Subset:  IM    
Southern Regional Research Center, Agricultural Research Service, US Department of Agriculture, New Orleans, LA 70124, USA.
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MeSH Terms
Aspergillus / genetics*
Culture Media
Fatty Acid Desaturases / genetics*
Gene Deletion
Genes, Fungal / genetics*
Genetic Vectors / genetics
Linoleic Acid / genetics
Mycelium / genetics
Spores, Fungal / genetics
Reg. No./Substance:
0/Culture Media; 2197-37-7/Linoleic Acid; EC 1.14.19.-/Fatty Acid Desaturases; EC 1.14.99.-/delta-12 fatty acid desaturase

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