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Mutations to LmIFRD affect cell wall integrity, development and pathogenicity of the ascomycete Leptosphaeria

Angela P Van de Wouw1, Filomena A Pettolino, Barbara J Howlett

  • 1School of Botany, The University of Melbourne, Vic., Australia.

Fungal Genetics and Biology : FG & B
|June 23, 2009
PubMed

Insights

Altering LmIFRD gene expression in Leptosphaeria maculans impacts fungal cell wall integrity, affecting growth, pathogenicity, and enzyme tolerance. This study reveals key changes in cell wall composition for this important plant pathogen.

Area of Science:

  • Mycology
  • Plant Pathology
  • Molecular Biology

Background:

  • Fungal cell wall integrity is crucial for growth, development, and pathogenicity.
  • The ascomycete Leptosphaeria maculans is an important pathogen of Brassica napus.
  • The role of LmIFRD in L. maculans cell wall structure and function is unknown.

Purpose of the Study:

  • To investigate the function of the LmIFRD gene in Leptosphaeria maculans.
  • To determine the impact of LmIFRD gene expression alterations on cell wall integrity and pathogenicity.
  • To analyze the cell wall composition of L. maculans mutants with altered LmIFRD expression.

Main Methods:

  • Generation and characterization of T-DNA insertional and gene-silencing mutants of LmIFRD.
  • Assessment of fungal growth, germination, sporulation, and pathogenicity assays on Brassica napus.
  • Enzyme and cell wall-disrupting compound tolerance assays.
  • Lectin binding experiments and monosaccharide linkage analysis of fungal cell walls.

Main Results:

  • Truncation of LmIFRD resulted in slower germination, reduced sporulation, loss of pathogenicity, and increased tolerance to cell wall degrading agents.
  • Silencing of LmIFRD led to increased germination, sporulation, earlier infection, and decreased tolerance to cell wall degrading agents.
  • Mutants exhibited altered cell wall integrity, with the T-DNA mutant showing increased 1,3-linked galactose and chitin.

Conclusions:

  • LmIFRD plays a critical role in regulating cell wall integrity and pathogenicity in Leptosphaeria maculans.
  • Altered LmIFRD expression leads to significant changes in cell wall composition, including polysaccharide content and structure.
  • This study provides the first analysis of cell wall monosaccharide linkage composition for spores and mycelia of a dothideomycete.

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