Characterization of the Aspergillus parasiticus delta12-desaturase gene: a role for lipid metabolism in the Aspergillus-seed interaction.
In the mycotoxigenic oilseed pathogens Aspergillus flavus and Aspergillus parasiticus and the model filamentous fungus Aspergillus nidulans, unsaturated fatty acids and their derivatives act as important developmental signals that affect asexual conidiospore, sexual ascospore and/or sclerotial development. To dissect the relationship between lipid metabolism and fungal development, an A. parasiticus Delta(12)-desaturase mutant that was unable to convert oleic acid to linoleic acid and was thus impaired in polyunsaturated fatty acid biosynthesis was generated. The Delta(12)-desaturase mutant demonstrates delayed spore germination, a twofold reduction in growth, a reduced level of conidiation and complete loss of sclerotial development, compared to the wild-type. Host colonization is impaired, as reflected by a decrease in conidial production on live peanut and corn seed by the mutant compared to the wild-type. Similarly, the previously isolated A. nidulans Delta(12)-desaturase mutant has reduced colonization capabilities compared to the wild-type. Therefore, desaturation mutants display a key requisite that affords a genetic solution to oilseed crop contamination by mycotoxigenic Aspergillus species: a reduction in the production of conidia, the infectious particle of the pathogenic aspergilli.
Wilson
Richard A
RA
Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Calvo
Ana M
AM
Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.
Chang
Perng-Kuang
PK
Southern Regional Research Center, Agricultural Research Service, US Department of Agriculture, New Orleans, LA 70124, USA.
Keller
Nancy P
NP
Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA.
D010367:Arachis / Q000382:microbiology; D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D004271:DNA, Fungal / Q000737:chemistry / Q000302:isolation & purification; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D019787:Linoleic Acid / Q000096:biosynthesis; D050356:Lipid Metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D019301:Oleic Acid / Q000378:metabolism; D012639:Seeds / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013172:Spores, Fungal / Q000254:growth & development; D003313:Zea mays / Q000382:microbiology
D004271:DNA, Fungal; D005231:Fatty Acids, Unsaturated; D019301:Oleic Acid; D019787:Linoleic Acid; D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase