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Genetic Manipulation of the Plant Pathogen Ustilago maydis to Study Fungal Biology and Plant Microbe Interactions
11:42

Genetic Manipulation of the Plant Pathogen Ustilago maydis to Study Fungal Biology and Plant Microbe Interactions

Published on: September 30, 2016

A biosynthetic gene cluster for a secreted cellobiose lipid with antifungal activity from Ustilago maydis

Beate Teichmann1, Uwe Linne, Sandra Hewald

  • 1Department of Biology, Philipps-University Marburg, D-35032 Marburg, Germany.

Molecular Microbiology
|September 14, 2007
PubMed

Insights

The fungus Ustilago maydis produces ustilagic acid (UA), a glycolipid biosurfactant critical for inhibiting fungal pathogen Botrytis cinerea. UA biosynthesis involves a 58 kb gene cluster with enzymes for fatty acid hydroxylation and glycosylation.

Area of Science:

  • Microbiology
  • Biochemistry
  • Plant Pathology

Background:

  • Ustilago maydis, a phytopathogenic fungus, produces significant quantities of the glycolipid biosurfactant ustilagic acid (UA).
  • Ustilagic acid is composed of hydroxylated palmitic acid linked to cellobiose, which is further modified by acetylation and acylation.

Purpose of the Study:

  • To elucidate the genetic basis and biosynthetic pathway of ustilagic acid (UA) in Ustilago maydis.
  • To investigate the role of UA in the antagonistic activity of U. maydis against Botrytis cinerea.

Main Methods:

  • Identification and analysis of a 58 kb gene cluster involved in UA biosynthesis.
  • Genetic manipulation of U. maydis and mass spectrometric analysis to assign enzyme functions.
  • Co-inoculation experiments to assess the antagonistic activity of wild-type and mutant U. maydis against Botrytis cinerea infection.

Main Results:

  • A 58 kb gene cluster with 12 open reading frames was identified, containing genes essential for UA biosynthesis.
  • Functional roles were assigned to Ahd1 (alpha-hydroxylation) and two P450 monooxygenases, Cyp1 and Cyp2 (terminal/subterminal hydroxylation).
  • U. maydis mutants deficient in UA biosynthesis lost their ability to inhibit Botrytis cinerea infection on tomato leaves.

Conclusions:

  • Ustilagic acid biosynthesis is encoded by a specific gene cluster in U. maydis.
  • The identified enzymes are crucial for the hydroxylation and glycosylation steps in UA production.
  • Secretion of UA is essential for the biocontrol activity of U. maydis against Botrytis cinerea.

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