title: Indole-3-acetic acid in Fusarium graminearum: Identification of biosynthetic pathways and characterization of physiological effects.
abstract: Fusarium graminearum is a devastating pathogenic fungus causing fusarium head blight (FHB) of wheat. This fungus can produce indole-3-acetic acid (IAA) and a very large amount of IAA accumulates in wheat head tissues during the first few days of infection by F. graminearum. Using liquid culture conditions, we have determined that F. graminearum can use tryptamine (TAM) and indole-3-acetonitrile (IAN) as biosynthetic intermediates to produce IAA. It is the first time that F. graminearum is shown to use the l-tryptophan-dependent TAM and IAN pathways rather than the indole-3-acetamide or indole-3-pyruvic acid pathways to produce IAA. Our experiments also showed that exogenous IAA was metabolized by F. graminearum. Exogenous IAA, TAM, and IAN inhibited mycelial growth; IAA and IAN also affected the hyphae branching pattern and delayed macroconidium germination. IAA and TAM had a small positive effect on the production of the mycotoxin 15-ADON while IAN inhibited its production. Our results showed that IAA and biosynthetic intermediates had a significant effect on F. graminearum physiology and suggested a new area of exploration for fungicidal compounds.
authors: State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, No.3 Taicheng Road, Yangling, Shaanxi 712100, PR China; Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Ave, Ottawa, ON K1A 0C6, Canada. Electronic address: luok1985@gmail.com.
authors: Kun
authors: K
authors: Luo
authors: Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Ave, Ottawa, ON K1A 0C6, Canada. Electronic address: Helene.Rocheleau@agr.gc.ca.
authors: Hélène
authors: H
authors: Rocheleau
authors: Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Ave, Ottawa, ON K1A 0C6, Canada; Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China. Electronic address: pengfeiqi@hotmail.com.
authors: Peng-Fei
authors: PF
authors: Qi
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China. Electronic address: ylzheng@sicau.edu.cn.
authors: You-Liang
authors: YL
authors: Zheng
authors: State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, No.3 Taicheng Road, Yangling, Shaanxi 712100, PR China. Electronic address: zhaohy@nwsuaf.edu.cn.
authors: Hui-Yan
authors: HY
authors: Zhao
authors: Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Ave, Ottawa, ON K1A 0C6, Canada. Electronic address: Therese.Ouellet@agr.gc.ca.
authors: Thérèse
authors: T
authors: Ouellet
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics*; D005670:Fusarium / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism; D025282:Mycelium / Q000187:drug effects / Q000254:growth & development; D010937:Plant Growth Regulators / Q000378:metabolism*; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development; D014255:Trichothecenes / Q000378:metabolism; D014908:Triticum / Q000382:microbiology; D014363:Tryptamines / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D007211:Indoles; D010937:Plant Growth Regulators; D014255:Trichothecenes; D014363:Tryptamines; C030820:tryptamine; C030737:indoleacetic acid; C046760:15-acetyldeoxynivalenol; D014364:Tryptophan; C016516:indole-3-acetonitrile
keywords: 15-Acetyldeoxynivalenol; Auxin biosynthesis; Fungal growth inhibition; Fusarium head blight; Gibberella zeae