Functional analyses of the nitrogen regulatory gene areA in Gibberella zeae.
Fusarium head blight caused by Gibberella zeae is a prominent disease of cereal crops that poses serious human health concerns due to the contamination of grains with mycotoxins. In this study, we deleted an orthologue of areA, which is a global nitrogen regulator in filamentous fungi, to characterize its functions in G. zeae. The areA deletion resulted in an inability to use nitrate as a sole nitrogen source, whereas urea utilization was partially available. The virulence of ΔareA strains on wheat heads was markedly reduced compared with the wild-type strain. The areA mutation triggered loss of trichothecene biosynthesis but did not affect zearalenone biosynthesis. The ΔareA strains showed immaturity of asci and did not produce mature ascospores. Chemical complementation by urea restored normal sexual development, whereas the virulence and trichothecene production were not affected by urea addition. GFP-AreA fusion protein was localized to nuclei, and its expression increased in response to nitrogen-limiting conditions. These results suggest that areA-dependent regulation of nitrogen metabolism is required for vegetative growth, sexual development, trichothecene biosynthesis, and virulence in G. zeae.
Department of Agricultural Biotechnology, Seoul National University, Korea.
Kyunghun
K
Min
Yungin
Y
Shin
Hokyoung
H
Son
Jungkwan
J
Lee
Jin-Cheol
JC
Kim
Gyung Ja
GJ
Choi
Yin-Won
YW
Lee
D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005874:Gibberella / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity*; D009584:Nitrogen / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014255:Trichothecenes / Q000096:biosynthesis; D014908:Triticum / Q000382:microbiology; D014774:Virulence
D005656:Fungal Proteins; D014157:Transcription Factors; D014255:Trichothecenes; D009584:Nitrogen