title: Involvement of threonine deaminase FgIlv1 in isoleucine biosynthesis and full virulence in Fusarium graminearum.
abstract: In this study we characterized FgIlv1, a homologue of the Saccharomyces cerevisiae threonine dehydratase (TD) from the important Fusarium head blight fungus Fusarium graminearum. TD catalyzes the first step in the biosynthesis pathway of isoleucine (Ile) for conversion of threonine (Thr) to 2-ketobutyrate (2-KB). The FgILV1 deletion mutant ΔFgIlv1-3 was unable to grow on minimal medium or fructose gelatin agar which lacked Ile. Exogenous supplementation of Ile or 2-KB but not Thr rescued the mycelial growth defect of ΔFgIlv1-3, indicating the involvement of FgIlv1 in the conversion of Thr to 2-KB in Ile biosynthesis. Additionally, exogenous supplementation of Methionine (Met) could also rescue the mycelial growth defect of ΔFgIlv1-3, indicating a crosstalk between Ile biosynthesis and Met catabolism in F. graminearum. Deletion of FgILV1 also caused defects in conidial formation and germination. In addition, ΔFgIlv1-3 displayed decreased virulence on wheat heads and a low level of deoxynivalenol (DON) production in wheat kernels. Taken together, results of this study indicate that FgIlv1 is an essential component in Ile biosynthesis and is required for various cellular processes including mycelial and conidial morphogenesis, DON biosynthesis, and full virulence in F. graminearum. Our data indicate the potential of targeting Ile biosynthesis for anti-FHB management.
authors.affiliation: Key Laboratory of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base/Key Laboratory of Control Technology and Standard for Agro-Product Safety and Quality (Nanjing), Ministry of Agriculture/Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Jianhong
authors.initials: J
authors.lastname: Xu
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Ji
authors.forename: Xianchao
authors.initials: X
authors.lastname: Yin
authors.forename: Jianrong
authors.initials: J
authors.lastname: Shi
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000235:genetics; D005670:Fusarium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D007532:Isoleucine / Q000096:biosynthesis*; D009154:Mutation; D025282:Mycelium / Q000235:genetics / Q000254:growth & development; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013172:Spores, Fungal / Q000235:genetics; D013913:Threonine Dehydratase / Q000235:genetics / Q000378:metabolism*; D014908:Triticum / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D000596:Amino Acids; D007532:Isoleucine; D013913:Threonine Dehydratase; D003542:Cystathionine gamma-Lyase