Transgenic expression of fungal accessory hemicellulases in Arabidopsis thaliana triggers transcriptional patterns related to biotic stress and defense response

PLoS One. 2017 Mar 2;12(3):e0173094. doi: 10.1371/journal.pone.0173094. eCollection 2017.


The plant cell wall is an abundant and renewable resource for lignocellulosic applications such as the production of biofuel. Due to structural and compositional complexities, the plant cell wall is, however, recalcitrant to hydrolysis and extraction of platform sugars. A cell wall engineering strategy to reduce this recalcitrance makes use of microbial cell wall modifying enzymes that are expressed directly in plants themselves. Previously, we constructed transgenic Arabidopsis thaliana constitutively expressing the fungal hemicellulases: Phanerochaete carnosa glucurnoyl esterase (PcGCE) and Aspergillus nidulans α-arabinofuranosidase (AnAF54). While the PcGCE lines demonstrated improved xylan extractability, they also displayed chlorotic leaves leading to the hypothesis that expression of such enzymes in planta resulted in plant stress. The objective of this study is to investigate the impact of transgenic expression of the aforementioned microbial hemicellulases in planta on the host arabidopsis. More specifically, we investigated transcriptome profiles by short read high throughput sequencing (RNAseq) from developmentally distinct parts of the plant stem. When compared to non-transformed wild-type plants, a subset of genes was identified that showed differential transcript abundance in all transgenic lines and tissues investigated. Intriguingly, this core set of genes was significantly enriched for those involved in plant defense and biotic stress responses. While stress and defense-related genes showed increased transcript abundance in the transgenic plants regardless of tissue or genotype, genes involved in photosynthesis (light harvesting) were decreased in their transcript abundance potentially reflecting wide-spread effects of heterologous microbial transgene expression and the maintenance of plant homeostasis. Additionally, an increase in transcript abundance for genes involved in salicylic acid signaling further substantiates our finding that transgenic expression of microbial cell wall modifying enzymes induces transcriptome responses similar to those observed in defense responses.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Glycoside Hydrolases / metabolism*
  • Plants, Genetically Modified
  • Stress, Physiological*
  • Transcription, Genetic*
  • Transcriptome


  • Glycoside Hydrolases
  • hemicellulase

Grants and funding

Funding for this research was provided by the Government of Ontario for the project Forest FAB: Applied Genomics for Functionalized Fiber and Biochemicals (ORF-RE-05-005), the Natural Sciences and Engineering Research Council of Canada. This work was also partly funded through the University of Toronto and the DOE Joint BioEnergy Institute ( supported by the U. S. Department of Energy, Office of Science, Office of Biological and Environmental Research, through contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U. S. Department of Energy. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.