Probing the role of cell wall feruloylation during maize development by differential expression of an apoplast targeted fungal ferulic acid esterase

PLoS One. 2020 Oct 9;15(10):e0240369. doi: 10.1371/journal.pone.0240369. eCollection 2020.


While many aspects of the growth of maize are well understood, the role of cell wall feruloylation particularly during internode elongation has not been firmly established, but results so far indicate that it has significant implications for both biofuel feedstock conversion and for crop yield. The growth of the cell wall is achieved by synthesis, integration and cross-linking between wall polymers. As ferulate oxidative coupling of arabinoxylan side chains constitutes a significant type of cross-link in grass cell walls, it is expected to have a crucial role in plant growth. Making use of plants expressing an apoplast targeted Aspergillus niger FAEA under the control of either a constitutive or an inducible promoter, the role of cell wall feruloylation in maize internode expansion was investigated. Analysis of FAEA expressing plants showed that where FAEA was targeted to the apoplast under a constitutive promoter, plants varied in stature either from semi-dwarf plants with a 40-60% height reduction, to extreme dwarf mutants with over 90% reduction in plant heights compared to controls. Results indicate that disruption of cell wall feruloylation by FAEA occurs before the start of rapid internode expansion is initiated and affects the normal course of internode elongation, resulting in short internodes and dwarfed plants. In contrast, when under the inducible Lm See1 senescence promoter, FAEA activity was found to be low up to the VT stage of development but increased significantly at the VR stage as plants began to senesce, strongly suggesting that normal cell wall feruloylation is required for the process of internode expansion. In addition, with apoplast targeted expression of FAEA under control of the senescence enhanced promoter it was possible to demonstrate decreased cell wall feruloylation without affecting internode expansion or other aspects of plant development.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aspergillus niger / enzymology*
  • Carboxylic Ester Hydrolases / genetics
  • Carboxylic Ester Hydrolases / metabolism*
  • Cell Wall / metabolism
  • Coumaric Acids / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Plant Leaves / anatomy & histology
  • Plant Leaves / growth & development
  • Plants, Genetically Modified / anatomy & histology
  • Plants, Genetically Modified / growth & development
  • Promoter Regions, Genetic
  • Xylans / metabolism*
  • Zea mays / anatomy & histology
  • Zea mays / genetics
  • Zea mays / growth & development*


  • Coumaric Acids
  • Fungal Proteins
  • Xylans
  • arabinoxylan
  • ferulic acid
  • Carboxylic Ester Hydrolases
  • feruloyl esterase

Grants and funding

Authors who received award: MMdOB Grants awarded: U.S. Department of Agriculture (USDA), grant number 2009-35318-o513, the Office of Science Engagement, Eberly College of Science and the Center of Excellence in Industrial Biotechnology. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.