Transgenic Research

, Volume 25, Issue 2, pp 173–186

Over-expression of the cucumber expansin gene (Cs-EXPA1) in transgenic maize seed for cellulose deconstruction


  • Sangwoong Yoon
    • Arkansas Biosciences Institute
    • Department of Plant SciencesUniversity of California
  • Shivakumar P. Devaiah
    • Department of Biological SciencesEast Tennessee State University
  • Seo-eun Choi
    • Department of MathematicsArkansas State University
  • Jeff Bray
    • Department of Veterinary Physiology and PharmacologyTexas A&M University
  • Robert Love
  • Jeffrey Lane
    • Hannah Engineering
  • Carol Drees
  • John H. Howard
    • Applied Biotechnology Institute
    • College of Agriculture and Technology and Arkansas Biosciences InstituteArkansas State University
Original Paper

DOI: 10.1007/s11248-015-9925-1

Cite this article as:
Yoon, S., Devaiah, S.P., Choi, S. et al. Transgenic Res (2016) 25: 173. doi:10.1007/s11248-015-9925-1


Plant cell wall degradation into fermentable sugars by cellulases is one of the greatest barriers to biofuel production. Expansin protein loosens the plant cell wall by opening up the complex of cellulose microfibrils and polysaccharide matrix components thereby increasing its accessibility to cellulases. We over-expressed cucumber expansin in maize kernels to produce enough protein to assess its potential to serve as an industrial enzyme for applications particularly in biomass conversion. We used the globulin-1 embryo-preferred promoter to express the cucumber expansin gene in maize seed. Expansin protein was targeted to one of three sub-cellular locations: the cell wall, the vacuole, or the endoplasmic reticulum (ER). To assess the level of expansin accumulation in seeds of transgenic kernels, a high throughput expansin assay was developed. The highest expressing plants were chosen and enriched crude expansin extract from those plants was tested for synergistic effects with cellulase on several lignocellulosic substrates. Activity of recombinant cucumber expansin from transgenic kernels was confirmed on these pretreated substrates. The best transgenic lines (ER-targeted) can now be used for breeding to increase expansin expression for use in the biomass conversion industry. Results of these experiments show the success of expansin over-expression and accumulation in transgenic maize seed without negative impact on growth and development and confirm its synergistic effect with cellulase on deconstruction of complex cell wall substrates.


Cucumber expansinOver-expressionTransgenic maizeExpansin assay

Supplementary material

11248_2015_9925_MOESM1_ESM.docx (795 kb)
Supplementary material 1 (DOCX 797 kb)

Copyright information

© Springer International Publishing Switzerland 2015