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Open Access Research article

Perturbation of Brachypodium distachyon CELLULOSE SYNTHASE A4 or 7 results in abnormal cell walls

Pubudu P Handakumbura12, Dominick A Matos13, Karen S Osmont1, Michael J Harrington1, Kyuyoung Heo4, Kabindra Kafle5, Seong H Kim5, Tobias I Baskin1 and Samuel P Hazen1*

Author affiliations

1 Biology Department, University of Massachusetts, Amherst, MA, USA

2 Plant Biology Graduate Program, University of Massachusetts, Amherst, MA, USA

3 Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, USA

4 Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, USA

5 Department of Chemical Engineering, Pennsylvania State University, University Park, PA, USA

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Citation and License

BMC Plant Biology 2013, 13:131  doi:10.1186/1471-2229-13-131

Published: 11 September 2013

Abstract

Background

Cellulose is an integral component of the plant cell wall and accounts for approximately forty percent of total plant biomass but understanding its mechanism of synthesis remains elusive. CELLULOSE SYNTHASE A (CESA) proteins function as catalytic subunits of a rosette-shaped complex that synthesizes cellulose at the plasma membrane. Arabidopsis thaliana and rice (Oryza sativa) secondary wall CESA loss-of-function mutants have weak stems and irregular or thin cell walls.

Results

Here, we identify candidates for secondary wall CESAs in Brachypodium distachyon as having similar amino acid sequence and expression to those characterized in A. thaliana, namely CESA4/7/8. To functionally characterize BdCESA4 and BdCESA7, we generated loss-of-function mutants using artificial microRNA constructs, specifically targeting each gene driven by a maize (Zea mays) ubiquitin promoter. Presence of the transgenes reduced BdCESA4 and BdCESA7 transcript abundance, as well as stem area, cell wall thickness of xylem and fibers, and the amount of crystalline cellulose in the cell wall.

Conclusion

These results suggest BdCESA4 and BdCESA7 play a key role in B. distachyon secondary cell wall biosynthesis.

Keywords:
Artificial microRNA; Brachypodium distachyon; Crystallinity; Secondary cell wall; Sum-frequency-generation vibration spectroscopy; Xylem