National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 Fenglin Road, 200032, Shanghai, China.
State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, 200032, Shanghai, China.
Nat Commun. 2019 Feb 25;10(1):922. doi: 10.1038/s41467-019-08726-9.
Fusarium graminearum is a destructive wheat pathogen. No fully resistant cultivars are available. Knowledge concerning the molecular weapons of F. graminearum to achieve infection remains limited. Here, we report that deletion of the putative secondary metabolite biosynthesis gene cluster fg3_54 compromises the pathogen's ability to infect wheat through cell-to-cell penetration. Ectopic expression of fgm4, a pathway-specific bANK-like regulatory gene, activates the transcription of the fg3_54 cluster in vitro. We identify a linear, C- terminally reduced and D-amino acid residue-rich octapeptide, fusaoctaxin A, as the product of the two nonribosomal peptide synthetases encoded by fg3_54. Chemically-synthesized fusaoctaxin A restores cell-to-cell invasiveness in fg3_54-deleted F. graminearum, and enables colonization of wheat coleoptiles by two Fusarium strains that lack the fg3_54 homolog and are nonpathogenic to wheat. In conclusion, our results identify fusaoctaxin A as a virulence factor required for cell-to-cell invasion of wheat by F. graminearum.
镰刀菌禾谷是一种具有破坏性的小麦病原体。目前还没有完全抗镰刀菌禾谷的品种。对镰刀菌禾谷实现侵染的分子武器的了解仍然有限。在这里，我们报告说，缺失假定的次生代谢产物生物合成基因簇 fg3_54 会削弱病原体通过细胞间渗透感染小麦的能力。FGM4 是一种途径特异性的 bANK 样调节基因，它在体外激活 fg3_54 簇的转录。我们鉴定出一种线性、C 端还原和 D-氨基酸残基丰富的八肽，即 fusaoctaxin A，它是由 fg3_54 编码的两个非核糖体肽合成酶的产物。化学合成的 fusaoctaxin A 恢复了 fg3_54 缺失的镰刀菌禾谷中的细胞间侵袭性，并使缺乏 fg3_54 同源物且对小麦无毒的两种镰刀菌菌株能够定殖小麦幼叶。总之，我们的结果表明 fusaoctaxin A 是镰刀菌禾谷细胞间侵袭小麦所必需的毒力因子。
