Identification of a novel polysaccharide in land plants and synthesis by members of the cellulose synthase-like F gene family

Little A1, Lahnstein J1, Jeffery DW2, Khor SF1, Schwerdt JG1, Shirley NJ1, Hooi M3, Xing X1,3, Burton RA1 and Bulone V1,3

  1. ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia.
  2. School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia.
  3. Adelaide Glycomics, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia.

As a significant component of monocot cell walls, (1,3;1,4)-β-glucan has conclusively been shown to be synthesised by the cellulose synthase-like F6 protein. In this study, we investigated the synthetic activity of other members of the barley CslF gene family using heterologous expression. As expected, the majority of the genes encode proteins that are capable of synthesising detectable levels of (1,3;1,4)-β-glucan, however, overexpression of HvCslF3 and HvCslF10 genes resulted in the synthesis of a novel polysaccharide. A simple diagnostic assay has been developed and the polysaccharide has been biochemically characterised. To demonstrate that this product was not an aberration of the heterologous system, the characteristic polysaccharide linkages were confirmed to be present in wild type barley tissues known to contain HvCslF3 and HvCslF10 transcripts. The finding of this linkage in land plants has significant implications for defining the cell wall content of many crop species and challenges the concept that members of a single Csl family possess the same carbohydrate synthetic activity.