FgIlv3a is crucial in branched-chain amino acid biosynthesis, vegetative differentiation, and virulence in Fusarium graminearum

  • Xin Liu
  • Yichen Jiang
  • Yinghui Zhang
  • Mingzheng Yu
  • Hongjun Jiang
  • Jianhong Xu
  • Jianrong ShiEmail author


Dihydroxyacid dehydratase (DHAD), encoded by ILV3, catalyses the third step in the biosynthetic pathway of branched-chain amino acids (BCAAs), which include isoleucine (Ile), leucine (Leu), and valine (Val). Enzymes involved in BCAA biosynthesis exist in bacteria, plants, and fungi but not in mammals and are therefore attractive targets for antimicrobial or herbicide development. In this study, three paralogous ILV3 genes (FgILV3A, FgILV3B, and FgILV3C) were identified in the genome of Fusarium graminearum, the causal agent of Fusarium head blight (FHB). Deletion of FgILV3A alone or combined with FgILV3B or FgILV3C indicated an important role for FgILV3A in BCAA biosynthesis. FgILV3A deletion mutants lost the ability to grow on medium lacking amino acids. Exogenous supplementation of 1 mM Ile and Val rescued the auxotrophy of ΔFgIlv3A, though 5 mM was required to recover the growth defects in ΔFgIlv3AB and ΔFgIlv3AC strains, indicating that FgIlv3b and FgIlv3c exhibit redundant but accessory roles with FgIlv3a in BCAA biosynthesis. The auxotrophy of ΔFgIlv3A resulted in pleiotropic defects in aerial hyphal growth, in conidial formation and germination, and in aurofusarin accumulation. In addition, the mutants showed reduced virulence and deoxynivalenol production. Overall, our study demonstrates that FgIlv3a is crucial for BCAA biosynthesis in F. graminearum and a candidate fungicide target for FHB management.


Fusarium graminearum dihydroxyacid dehydratase branched-chain amino acid biosynthesis paralogous FgILV3 genes virulence 


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Copyright information

© The Microbiological Society of Korea 2019

Authors and Affiliations

  • Xin Liu
    • 1
    • 2
  • Yichen Jiang
    • 1
    • 3
  • Yinghui Zhang
    • 1
    • 4
  • Mingzheng Yu
    • 1
  • Hongjun Jiang
    • 1
    • 5
  • Jianhong Xu
    • 1
    • 2
  • Jianrong Shi
    • 1
    • 2
    Email author
  1. 1.Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and NutritionJiangsu Academy of Agricultural SciencesNanjingP. R. China
  2. 2.School of Food and Biological EngineeringJiangsu UniveristyZhenjiangP. R. China
  3. 3.College of Food ScienceTibet Agriculture and Animal Husbandry UniversityTibetP. R. China
  4. 4.College of Life ScienceSanquan College of Xinxiang Medical UniversityXinxiangP. R. China
  5. 5.College of Plant ProtectionNanjing Agriculture UniversityNanjingP. R. China

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