Degradation of aromatic compounds through the β-ketoadipate pathway is required for pathogenicity of the tomato wilt pathogen Fusarium oxysporum f. sp. lycopersici

Mol Plant Pathol. 2012 Dec;13(9):1089-100. doi: 10.1111/j.1364-3703.2012.00818.x. Epub 2012 Jul 24.


Plant roots react to pathogen attack by the activation of general and systemic resistance, including the lignification of cell walls and increased release of phenolic compounds in root exudate. Some fungi have the capacity to degrade lignin using ligninolytic extracellular peroxidases and laccases. Aromatic lignin breakdown products are further catabolized via the β-ketoadipate pathway. In this study, we investigated the role of 3-carboxy-cis,cis-muconate lactonizing enzyme (CMLE), an enzyme of the β-ketoadipate pathway, in the pathogenicity of Fusarium oxysporum f. sp. lycopersici towards its host, tomato. As expected, the cmle deletion mutant cannot catabolize phenolic compounds known to be degraded via the β-ketoadipate pathway. In addition, the mutant is impaired in root invasion and is nonpathogenic, even though it shows normal superficial root colonization. We hypothesize that the β-ketoadipate pathway in plant-pathogenic, soil-borne fungi is necessary to degrade phenolic compounds in root exudate and/or inside roots in order to establish disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipates / metabolism*
  • Biosynthetic Pathways* / drug effects
  • Colony Count, Microbial
  • Flax / drug effects
  • Flax / microbiology
  • Fusarium / drug effects
  • Fusarium / enzymology
  • Fusarium / growth & development
  • Fusarium / pathogenicity*
  • Gene Deletion
  • Hydrocarbons, Aromatic / metabolism*
  • Hydrocarbons, Aromatic / pharmacology
  • Intramolecular Lyases / chemistry
  • Intramolecular Lyases / isolation & purification
  • Lycopersicon esculentum / drug effects
  • Lycopersicon esculentum / microbiology*
  • Pest Control, Biological
  • Plant Diseases / microbiology*
  • Plant Roots / drug effects
  • Plant Roots / microbiology
  • Spores, Fungal / drug effects
  • Spores, Fungal / growth & development


  • Adipates
  • Hydrocarbons, Aromatic
  • 3-oxoadipic acid
  • Intramolecular Lyases
  • 3-carboxy-cis-cis-muconate cyclase