How to make a tumour: cell type specific dissection of Ustilago maydis-induced tumour development in maize leaves

New Phytol. 2018 Mar;217(4):1681-1695. doi: 10.1111/nph.14960. Epub 2018 Jan 4.


The biotrophic fungus Ustilago maydis causes smut disease on maize (Zea mays), which is characterized by immense plant tumours. To establish disease and reprogram organ primordia to tumours, U. maydis deploys effector proteins in an organ-specific manner. However, the cellular contribution to leaf tumours remains unknown. We investigated leaf tumour formation at the tissue- and cell type-specific levels. Cytology and metabolite analysis were deployed to understand the cellular basis for tumourigenesis. Laser-capture microdissection was performed to gain a cell type-specific transcriptome of U. maydis during tumour formation. In vivo visualization of plant DNA synthesis identified bundle sheath cells as the origin of hyperplasic tumour cells, while mesophyll cells become hypertrophic tumour cells. Cell type-specific transcriptome profiling of U. maydis revealed tailored expression of fungal effector genes. Moreover, U. maydis See1 was identified as the first cell type-specific fungal effector, being required for induction of cell cycle reactivation in bundle sheath cells. Identification of distinct cellular mechanisms in two different leaf cell types and of See1 as an effector for induction of proliferation of bundle sheath cells are major steps in understanding U. maydis-induced tumour formation. Moreover, the cell type-specific U. maydis transcriptome data are a valuable resource to the scientific community.

Keywords: Ustilago maydis; cell differentiation; cell type specificity; effectors; laser capture microdissection; maize (Zea mays); metabolic reprogramming; tumour formation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Differentiation
  • Cell Division
  • Cell Proliferation
  • Cell Shape
  • Cell Wall / metabolism
  • Chloroplasts / metabolism
  • Chloroplasts / ultrastructure
  • DNA / biosynthesis
  • Endoreduplication
  • Fungal Proteins / metabolism
  • Gene Expression Regulation, Plant
  • Plant Leaves / cytology
  • Plant Leaves / microbiology*
  • Plant Leaves / ultrastructure
  • Plant Tumors / microbiology*
  • Ustilago / physiology*
  • Zea mays / genetics
  • Zea mays / microbiology*
  • Zea mays / ultrastructure


  • Fungal Proteins
  • DNA

Associated data

  • GENBANK/GSE105770